Faculty Profiles - DOKI, Shinji

Papers - DOKI, Shinji

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Funabot-Sleeve: A Wearable Device Employing McKibben Artificial Muscles for Haptic Sensation in the Forearm Reviewed International journal

Yanhong Peng, Yusuke Sakai, Yuki Funabora, Kenta Yokoe, Tadayoshi Aoyama, Shinji Doki

IEEE Robotics and Automation Letters Vol. 10 ( 2 ) page： 1944 - 1951 2025.2

Preliminary Study on Task Division for UAV-Based Visual Inspection of Large Structures with Multiple Flights Using 3D Urban Models Reviewed International journal

Haneda M., Funabora Y., Doki S.

2025 IEEE/SICE International Symposium on System Integration, SII 2025 page： 1381 - 1386 2025

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：2025 IEEE/SICE International Symposium on System Integration, SII 2025

This paper addresses the problem of task division based on 3D urban models for visual inspection using a UAV with multiple flights. When inspecting large structures for damage detection, UAVs are often flown multiple times to obtain high-resolution data from all areas. Research is progressing on coverage path planning (CPP) methods for data collection in a single flight, and the 3D models of the target required for this can be readily obtained. However, the automation of task division for each flight has not been extensively studied. Because the scale of the target is large, it is necessary to execute a task division method that optimizes the performance efficiency of UAVs within a practical calculation time. This paper presents a task division method for data collection by multiple flights of a UAV based on the decomposition of the 3D urban models. Forming a framework in which data collection tasks are divided based on the 3D mesh decomposition, and then the CPP method is applied to each task, this enables efficient inspection of large-scale structures. In this paper, we implement three basic methods based on the strategies of avoiding going far, equalizing the amount of each task, and reducing unnecessary movement as preliminary research. Each method applies to objects on a scale of several hundred meters, and evaluates their performance in automated data collection.

DOI： 10.1109/SII59315.2025.10870973

Viewpoint Generation Algorithm for Gimbal-Mounted Robots for Visual Inspection of Civil Engineering Structures Reviewed International journal Open Access

Haneda M., Wu W., Funabora Y., Doki S., Doki K.

IEEE Access 2025

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE Access

We propose a viewpoint generation algorithm for the visual inspection of civil engineering structures using robots equipped with a gimbal-mounted camera. This algorithm enables robots to completely inspect target surfaces at the required spatial resolution while reducing movement by effectively utilizing the gimbal. Previous studies generally assume that the camera is always oriented orthogonally to the target surface, and they focus on the inspection position optimization problem, resulting in the underutilization of gimbals and heavy movement of robots. In this study, firstly we have formulated the conditions under which the collected data’s quality does not deteriorate in terms of damage detection, and we have relaxed the orthogonal measuring restrictions. Based on the conditions, we propose a viewpoint generation algorithm that can carry out inspection work by changing measurement orientations instead of moving the robot. In simulation experiments, our method reduces inspection time by 47.7% compared to the benchmark method for the same tasks of inspecting a pier surface with the required spatial resolution. In addition, the viewpoint generation time was reduced by 96.8% compared to the benchmark method. We also conducted experiments in real environments using pan-tilt heads and confirmed that our algorithm can collect data qualified for the damage detection of visual inspections.

DOI： 10.1109/ACCESS.2025.3546992

Feasibility of loop-gain tuning for general measurement systems inspired by quantum locking for DECIGO Reviewed International journal

Ishikawa, T; Kawasaki, Y; Tsuji, K; Shimizu, R; Umemura, K; Wu, B; Iwaguchi, S; Michimura, Y; Nagano, K; Enomoto, Y; Komori, K; Doki, S; Furusawa, A; Kawamura, S

CLASSICAL AND QUANTUM GRAVITY Vol. 41 ( 21 ) 2024.11

Language：English Publishing type：Research paper (scientific journal) Publisher：Classical and Quantum Gravity

A series of quantum locking theories have been proposed to enhance the quantum-noise-limited target sensitivity of the DECi-hertz Interferometer Gravitational wave Observatory. The quantum locking that uses a square completion optimizes the sensitivity across all frequencies. However, a substantial amount of data-series must be post-processed since the square completion is a form of signal processing technique. This paper approaches the optimal sensitivity across all frequencies from an alternative perspective: by optimizing the frequency dependence of a servo gain in a feedback loop. The optimal servo gain is formulated by comparing the alternative method with the square completion method for the same optical setup. This will be shown in general noise issues extending the framework of the quantum locking. We find that the optimal servo gain forms a non-feasible filter but has certain characteristics. We also find that the noise of the measurement signal deteriorates proportionally to the noise measured in the feedback loop when the servo gain is slightly imperfect.

DOI： 10.1088/1361-6382/ad7cb6

Gravity Compensation Method for Whole Body-Mounted Robot With Contact Force Distribution Sensor Reviewed International journal

Masaoka, S; Funabora, Y; Doki, S

IEEE ROBOTICS AND AUTOMATION LETTERS Vol. 9 ( 9 ) page： 7843 - 7850 2024.9

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE Robotics and Automation Letters

The emergence of sheet-type force distribution sensors has allowed direct measurement of contact force. We developed a wearable assistive robot that can directly measure contact force and investigated the gravity compensation effect of contact-force-based control. For conventional robots that do not measure the force acting between the robot and the human body (contact force) directly, a precise robot model is required for gravity compensation, which is difficult to implement in software. In the first experiment, we examined a method of gravity compensation using only joint sensors in torque-based control, which is a common conventional method, and assessed the difficulty of this method. In the next experiment, which involved one healthy subject, we confirmed that contact-force-based control has a significant gravity compensation effect without requiring a rigorous robot model. Experiments with two additional healthy subjects using the same parameters revealed that even rough parameter tuning can produce a gravity compensation effect. This letter not only proposes a simplified gravity compensator for wearable assistive robots but also demonstrates the robustness of parameter tuning in contact-force-based control under static conditions. Based on the findings of this letter, we will further study the possibility of other kinds of disturbance compensation and dynamic conditions in the future.

DOI： 10.1109/LRA.2024.3433308

Funabot-Finger Cot: Bio-Inspired Worm Robot for Peristaltic Wave Locomotion and Tubular Structure Climbing Reviewed International journal

Sato Y., Peng Y., Funabora Y., Doki S.

2024 IEEE/SICE International Symposium on System Integration, SII 2024 page： 1387 - 1392 2024

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：2024 IEEE/SICE International Symposium on System Integration, SII 2024

In recent years, robots that move on tubular structures have attracted much attention. These robots are used in a variety of applications and provide very significant benefits such as increased work efficiency, improved safety, and reduced work costs. Robots that move on tubular structures include robots that move while grasping objects, robots that move while attached by suction cups or adhesive materials, and robots that move by wheels. However, conventional robots have large, rigid parts and cannot move in confined environments because they need sufficient mechanical strength to climb against gravity. This is where our research group's Funabot-Finger Cot comes in. This device is a small device with pneumatically expandable artificial muscles fixed to a cloth, and its movement can be controlled by controlling the pattern of air pressure application. The repeated contraction and relaxation characteristics of the device suggest that it could be used as a robot that moves on a tubular structure that mimics the peristaltic movement of living organisms. Peristaltic motion is the coordinated contraction and relaxation of muscles, which allows the robot to move over the ground, gaps, and objects. The Funabot-Finger Cot makes several contributions. First, because it is made of flexible fabric, it can be wrapped around structures of various shapes. Its thinness also allows it to move efficiently in constrained environments that are difficult for conventional robots. Secondly Cost-effective and cost-saving. Because this is small robot and made of common fabric and a small amount of artificial muscle, they can be made inexpensively and easily. The most notable feature is its versatility. Finally, the fact that the actuator supports both circular longitudinal contraction allows for more complex movements. This study will focus on the third advantage in particular, evaluating movement over tubular structures in circular contraction and in longitudinal contraction.

DOI： 10.1109/SII58957.2024.10417394

Evaluation and Enhancement of Resolution-Aware Coverage Path Planning Method for Surface Inspection Using Unmanned Aerial Vehicles Reviewed International journal

Wu, WT; Funabora, Y; Doki, S; Doki, K; Yoshikawa, S; Mitsuda, T; Xiang, JY

IEEE ACCESS Vol. 12 page： 16753 - 16766 2024

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE Access

We implemented and evaluated our previous path planning method for inspection using unmanned aerial vehicles (UAVs) in real-world, and identified its shortcomings in handling positioning errors. Then, we proposed an enhanced method to address this problem. The previous method theoretically guaranteed complete coverage of targets and data quality. However, we verified it in bridge inspection experiments and found that the former has not been ensured. The crucial factors of data omission are clarified as the errors in UAV positioning. Our previous method relies on appropriately setting ideal allowances to counteract positioning errors, which is challenging in practice. Therefore, we proposed an enhanced path planning method, which adaptively adjusts allowances according to positioning error to prevent omission while minimizing waypoints. In the simulation including positioning disturbances, the enhanced method consistently achieved full coverage in 1000 times simulation with over 28% waypoints less than the previous one.

DOI： 10.1109/ACCESS.2024.3359056

Pole Change Method Without Torque Fluctuation in Multiphase IM Drive System Reviewed International journal

Kobayashi M., Doki S., Nikaido R., Chiba A., Kobayashi M.

ECCE Europe 2024 - Energy Conversion Congress and Expo Europe, Proceedings 2024

Language：English Publishing type：Research paper (international conference proceedings) Publisher：ECCE Europe 2024 - Energy Conversion Congress and Expo Europe, Proceedings

In this study, it is shown that the multiphase IM can be regarded as a superposition of independent, decoupled large-pole and small-pole IM by using the VSD conversion in a multiphase IM drive system (IMTS) that actively utilizes pole change. By deriving a mathematical formula, the factor of torque fluctuation response due to conflict of voltage limiter during pole number change is identified. In addition, the pole change law without torque fluctuation in multiphase IM is proposed by using the formula.

DOI： 10.1109/ECCEEurope62508.2024.10751919

Expansion of Field-Oriented Control Operation Range of Dual Three-Phase Synchronous Motor with Flux Weakening Control in the Inverter Overmodulation Region Reviewed International journal

Hao R., Doki S.

ECCE Europe 2024 - Energy Conversion Congress and Expo Europe, Proceedings 2024

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：ECCE Europe 2024 - Energy Conversion Congress and Expo Europe, Proceedings

As the theories for expanding the operation range, the inverter overmodulation strategy and the flux weakening control method are widely used on the three-phase motors. In conventional research, it was found that a dual three-phase motor can be field-oriented-controlled in the overmodulation region easier than a three-phase motor. In this study, the theory of utilizing the flux weakening control and inverter overmodulation together for Dual Three-Phase Synchronous Motor is proposed, and the current reference calculation method under the flux weakening control is presented. The expansion performance of the proposed field-oriented control operation range is evaluated.

DOI： 10.1109/ECCEEurope62508.2024.10751838

Applications of Augmented Reality in Assisting Structure Surface Data Collection Using Unmanned Aerial Vehicles Reviewed International journal Open Access

Wu, WT; Hong, YH; Funabora, Y; Doki, S; Doki, K

IEEE ACCESS Vol. 12 page： 143106 - 143117 2024

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE Access

This paper investigates the feasibility and effectiveness of applying AR (Augmented Reality) technology to assist UAV (Unmanned Aerial Vehicle) pilots in collecting data for structure inspections. The challenge of using UAVs to collect inspection data is that pilots could not precisely determine where to collect qualified data. Using AR technology to provide visual assistance to pilots is expected to tackle this challenge. However, previous research has focused on enhancing pilots' perception of UAVs' current situations and goal waypoints. How to indicate ideal data collection poses (positions and orientations) with AR and the practical improvement that AR can bring remain unknown. Therefore, we proposed a system that visualizes ideal poses as AR models, allowing pilots to easily collect qualified data by aligning UAVs with these models and taking images. Experiments in virtual and real confirmed that the system significantly improves the proportion of the valid inspection area (achieving up to 99.3%).

DOI： 10.1109/ACCESS.2024.3461174

Verification of Mehcanism How Fabric Actuator Evoke Pinched Tactile by Using Force Distribution Sensor Reviewed International journal

Masaoka S., Sato Y., Funabora Y., Doki S.

Proceedings of the 2024 IEEE International Conference on Cyborg and Bionic Systems, CBS 2024 page： 263 - 266 2024

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：Proceedings of the 2024 IEEE International Conference on Cyborg and Bionic Systems, CBS 2024

Various haptic devices are attracting attention in many fields. However, conventional haptic devices have some limits. Electrical stimulation devices are lightweight and flexible, but the area in which the tactile stimulation is provided is spatially limited, and the variation of the tactile stimulation is few. The mechanical stimulation method can provide a widely stable tactile sensation, but it requires a rigid drive or limited mounting area. We developed a fabric actuator that is flexible and freely deformable soft actuator. This actuator is expected to be used in haptic devices, and it was clarified that the device can evoke an unprecedented pinched sensation by the wearer's sensation. However, it was not clear what mechanism evoked the pinched tactile. In this paper, we used a distribution sensor that can measure shear force to clarify the mechanism. Based on the results of the experiments, it was clarified that the three-dimensional intersections of the artificial muscles evoke a variety of force directions, contributing to the induction of the pinched tactile stimuli that were not previously possible.

DOI： 10.1109/CBS61689.2024.10860666

Verification of Compliance on Funabot-Plate: Semisoft Assistive Robot with Artificial Muscle and Rigid Plate Reviewed International journal

Masaoka S., Yasuda R., Funabora Y., Doki S.

2024 18th International Conference on Control, Automation, Robotics and Vision, ICARCV 2024 page： 441 - 446 2024

Language：English Publishing type：Research paper (international conference proceedings) Publisher：2024 18th International Conference on Control, Automation, Robotics and Vision, ICARCV 2024

Compliance is important for the rehabilitation of wearable assistive robots. Various methods have been studied to improve the compliance of wearable robots, such that the use of impedance control of actuators and soft actuators with high compliance. On the other hand, for robots whose degrees of freedom of movement are limited by rotational axes like conventional robots, compliance performance may deteriorate due to mounting misalignment even if the actuator is designed optimally. Soft wearable devices that do not have rigid joints and are composed of soft base materials also exist, but the force is dispersed and cannot exert great force. Our Funabot- Plate consists of a base cloth, McKibben-type pneumatic artificial muscles, and thin, rigid plates that efficiently transfer the exerted force of the artificial muscles to the human body. Thus, Funabot-Plate expects a high output efficiency while high compliance. To verify the structural validity of the Funabot- Plate, two experiments were conducted to quantitatively compare its compliance characteristics with the rigid-frame robot. Through the measurement experiments, we were able to quantitatively evaluate that the structure of Funabot- Plate exhibited higher compliance in both conditions, transparent mode and assist mode, when compared to conventional rigid-frame robots.

DOI： 10.1109/ICARCV63323.2024.10821572

The Impact of Equipment Specifications on the Efficiency of Visual Inspection using Unmanned Aerial Vehicles Reviewed International journal

Wu W., Funabora Y., Doki S., Doki K.

10th 2024 International Conference on Control, Decision and Information Technologies, CoDIT 2024 page： 1505 - 1510 2024

Language：English Publishing type：Research paper (international conference proceedings) Publisher：10th 2024 International Conference on Control, Decision and Information Technologies, CoDIT 2024

This manuscript investigates the impact of unmanned aerial vehicles (UAVs) and their cameras' key specifications on the efficiency of infrastructure visual inspections using UAVs. The challenges of UAV-based inspection data collection include reducing necessary waypoints to improve inspection efficiency while collecting desired data for sure. Existing studies generally concentrated on optimizing the efficiency of UAVs' inspection trajectories and waypoints when equipment is given. However, the impacts of equipment specifications and their selections have not been investigated, yet they also significantly affect inspection efficiency. This manuscript surveys the key specifications of current equipment available for inspection and investigates the variation in efficiency through inspection simulations with different equipment specification combinations. Simulation results reveal that with the highest pose accuracy achievable by existing UAV platforms, it is possible to achieve efficient inspection. However, such high pose accuracy may be difficult to achieve, underscoring the importance of targeted selection of camera focal lengths according to UAV specifications and the types of pose errors. Additionally, using higher-resolution cameras may substantially improve the efficiency of high-resolution data collection tasks, which is a more practical solution for enhancing efficiency than further improvements in UAV pose accuracy. The conclusions drawn from this research provide actionable guidelines for equipment selection and development and lay the foundations of efficiency modeling, ultimately contributing to the advancement of UAV-based inspection methodologies.

DOI： 10.1109/CoDIT62066.2024.10708530

Smooth Pole Change Method for Multiphase Induction Motor Drive System Reviewed International journal

Kobayashi M., Doki S., Kato H., Itoh J.I., Kobayashi M.

2024 IEEE International Conference on Electrical Systems for Aircraft, Railway, Ship Propulsion and Road Vehicles and International Transportation Electrification Conference, ESARS-ITEC 2024 2024

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：2024 IEEE International Conference on Electrical Systems for Aircraft, Railway, Ship Propulsion and Road Vehicles and International Transportation Electrification Conference, ESARS-ITEC 2024

In this study, it is shown that the multiphase IM can be regarded as a superposition of independence, decoupled large-pole and small-pole IM by using the VSD conversion and multiphase IM drive system (IMTS: Induction Motor drive with Transmission System) that actively utilizes pole change is proposed. By deriving a mathematical formula, the factor of torque fluctuation response due to conflict of voltage limiter during pole number change is identified. In addition, the pole change law without torque fluctuation in multiphase IM is proposed by using the formula. An actual machine experiment is also conducted to confirm the effectiveness of the proposed method.

DOI： 10.1109/ESARS-ITEC60450.2024.10819802

Investigation of Sensory Provision for Calf and Shin Using Fabric Actuator Reviewed International journal

Masaoka S., Fukatsu H., Funabora Y., Doki S.

Proceedings of the 2024 IEEE International Conference on Cyborg and Bionic Systems, CBS 2024 page： 259 - 262 2024

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：Proceedings of the 2024 IEEE International Conference on Cyborg and Bionic Systems, CBS 2024

Various haptic devices are attracting attention in many fields, and research and development on haptic devices using soft actuators are underway. We developed a fabric actuator that is flexible and freely deformable soft actuator. This actuator is expected to be used in haptic devices, and it was clarified the device can evoke Grasp, Pinch, Press, and Twist tactile at one actuator in the upper arm and forearm. We focus on the site extensibility of this actuator. In this paper, we verified what types of tactile sensations this actuator can evoke in the shin and calf via experiments with one experimenter as the subject. As a result, mainly three results were obtained: The first was the area where the tactile work was accurately answered. Second, the subject was confused about whether the pattern was Press or Grasp. Third, it was difficult to evoke Pinch tactile. After consideration, it was suggested that the method of attachment is important. In the future, we aim to achieve diverse tactile recall with the leg while investigating other causes.

DOI： 10.1109/CBS61689.2024.10860485

An Innovative Discrete-Time dq-Axis Model Considering Phase Discretization Error for High-Speed IM Drive and Its Analysis Reviewed International journal

Fang Z., Doki S.

2024 IEEE International Conference on Electrical Systems for Aircraft, Railway, Ship Propulsion and Road Vehicles and International Transportation Electrification Conference, ESARS-ITEC 2024 2024

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：2024 IEEE International Conference on Electrical Systems for Aircraft, Railway, Ship Propulsion and Road Vehicles and International Transportation Electrification Conference, ESARS-ITEC 2024

The field-oriented control (FOC)-based auto current regulators (ACRs) are commonly designed under the ideal assumption that the phase is obtained continuously when performing the Park transformation, but the current regulators are always discretely implemented. It will inevitably introduce non-negligible phase discretization errors with the increase of fundamental-to-switching(control) frequency ratio (fe/fs). Therefore, an innovative discrete-time dq-axis model for AC motor considering the Park transformation phase discretization error is proposed and the corresponding ACR is designed. Then, the decoupling performance and stability of the proposed closedloop current system are theoretically analyzed using complex vector method. Furthermore, the proposed discretization method is subsequently performed on an induction motor (IM) and verified through simulations and experiments. Eventually, the Padé approximant order of the discrete control matrix is discussed.

DOI： 10.1109/ESARS-ITEC60450.2024.10819793

Funabot-Suit: A bio-inspired and McKibben muscle-actuated suit for natural kinesthetic perception Reviewed International journal

Yanhong Peng, Yusuke Sakai, Koki Nakagawa, Yuki Funabora, Tadayoshi Aoyama, Kenta Yokoe, Shinji Doki

Biomimetic Intelligence and Robotics Vol. 3 ( 4 ) page： 100127 - 100127 2023.12

Model predictive current control with a finite set of novel voltages and modulator in permanent magnet synchronous motor drives Reviewed International coauthorship International journal

Kawai, H; Cordier, J; Kennel, R; Doki, S

IET ELECTRIC POWER APPLICATIONS Vol. 17 ( 9 ) page： 1197 - 1211 2023.9

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：IET Electric Power Applications

Finite control set model predictive control (FCS–MPC) has been deployed extensively in electric motor drives and power electronics applications. Many advantages, including fast transient response, have been reported. However, the improvement of its steady-state performance, that is, suppression of current ripple, is one of the main problems of a conventional FCS–MPC strategy. This article presents a current control strategy based on FCS–MPC using the concept of variable voltage smoothing. In the proposed method, a finite set of novel voltage vectors, produced by the smoothing process, are introduced as candidate control input candidates, and the controller generates the optimum output voltage using a modulator integrated with the FCS–MPC scheme. Thus, the voltage candidates are generated flexibly, and a suitable voltage for acceptable steady-state performance is determined as the control input. In addition, the smoothness in the proposed concept can be updated automatically depending on the drive situation, that is, transient, or steady-state operation, thus avoiding degradation of dynamic performance. Simulation and experimental results obtained with a permanent magnet synchronous motor drive system demonstrate that the proposed control strategy is effective to achieve current control with fast tracking performance while suppressing current ripple.

DOI： 10.1049/elp2.12335

Direct Speed Control Based on Finite Control Set Model Predictive Control With Voltage Smoother Reviewed International coauthorship International journal

Kawai, H; Zhang, ZB; Kennel, R; Doki, S

IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS Vol. 70 ( 3 ) page： 2363 - 2372 2023.3

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE Transactions on Industrial Electronics

A direct speed control strategy based on finite control set model predictive control (FCS-MPC) with a voltage smoother is presented herein. In the proposed concept, a finite set of smoothed voltage vectors characterized by an adjustable amplitude and a movable origin is introduced as voltage candidates in the FCS-MPC scheme. The controller predicts the future current and speed and outputs the optimal smoothed voltage using pulse-width modulation. Owing to this control scheme, an abrupt change in the output voltage, which causes a large current ripple, is avoided without additional computational costs. Simulation and experimental results obtained using a permanent magnet synchronous motor fed by a two-level three-phase inverter show that the proposed method effectively reduces the current ripple while achieving a high dynamic drive compared with the conventional FCS-MPC scheme.

DOI： 10.1109/TIE.2022.3174298

A Novel Decoupling Control Scheme for Non-Salient Multi-Three-Phase Synchronous Machines Based on Multi-Stator Model Reviewed International journal Open Access

Wang, S; Imai, K; Doki, S

IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS Vol. 59 ( 1 ) page： 886 - 896 2023.1

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE Transactions on Industry Applications

As competitive alternatives to conventional three-phase synchronous machines, synchronous multi-three-phase machines (MTPMs) are gaining increasing interests in various fields such as electrified transportation and power generation. The modular configuration is preferred for multi-three-phase drives in specific applications regarding the availability of advanced three-phase power electronics techniques and the superior capability of fault tolerance. The multi-stator (MS) modelling would be an ideal solution for the control of such modular drives as it facilitates power sharing among winding sets in a straightforward way and enables simple post fault strategies compared with the well-known vector space decomposition (VSD) modelling approach. Nevertheless, the strong magnetic coupling existing in MS model has hindered its use due to the instability and the performance deterioration issue. To solve the problem, a new decoupling control scheme directly applied in MS frame is proposed in this paper. The proposed method can deal with non-salient multi-three-phase machines whose three-phase winding sets can be identical or different, under the assumption of the sinusoidal airgap flux. Furthermore, it is shown by analysis the proposed method is characterized by significant simplicity and flexibility compared with the existing decoupling methods. The effectiveness of the proposed method has been verified through experiments including a single-side operation, a power-sharing test, and a post fault tolerant operation on a non-salient dual three-phase permanent magnet synchronous machine with quasi sinusoidal air gap flux.

DOI： 10.1109/TIA.2022.3211827

Active Damping Control Method for Different Dual-Parallel-SPMSM Systems with Single Inverter Reviewed International journal Open Access

Park, C; Doki, S

IEEJ JOURNAL OF INDUSTRY APPLICATIONS Vol. 12 ( 1 ) page： 73 - 83 2023

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：IEEJ Journal of Industry Applications

This paper presents a stabilization method for different dual parallel surface permanent magnet synchronous motor (SPMSM) systems with a single inverter. When a single inverter drives two synchronous motors, disturbance can cause a torque difference between the two motors. This can cause the motor’s electrical and mechanical resonance. Several damping control methods have been proposed to suppress such resonance. However, such methods consider that the parameters of the two motors are identical. When a single inverter controls two motors with different parameters, the damping control performance deteriorates. Besides, the motor’s resonance sound and current ripple increase. To address these problems, this paper proposes a control method for dual-parallel-SPMSM drive systems with a single inverter.

DOI： 10.1541/ieejjia.22006418

Extended EMF Observer of Dual Three-Phase Permanent Magnet Synchronous Motor Operable in Overmodulation Drive Reviewed International journal

Imai, K; Doki, S; Kondo, K; Aoki, Y

IEEJ JOURNAL OF INDUSTRY APPLICATIONS Vol. 12 ( 5 ) page： 901 - 913 2023

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEJ Journal of Industry Applications

This paper proposes a novel extended electromotive force (EEMF) observer of a dual three-phase permanent magnet synchronous motor (DTP-PMSM) operable to the position sensorless overmodulation drive. The overmodulation drive occurs in current harmonics, and the estimated EEMF also contains harmonic components, leading to ripple error in the estimated position. Based on the vector space decomposition (VSD) utilized in DTP-PMSM current control, the proposed method can decrease the current harmonics in the overmodulation and the harmonic components in the estimated EEMF, and it can also improve position estimation. The effectiveness of the proposed EEMF observer and the improvement in the position estimation were experimentally verified.

DOI： 10.1541/ieejjia.22005441

Clustering Method of Driving Scenes based on Road Shape by using Road Map Images Reviewed International journal

Hashimoto K., Yanagihara D., Kuniyuki H., Doki K., Funabora Y., Doki S.

4th International Conference on Electrical, Communication and Computer Engineering, ICECCE 2023 2023

Language：English Publishing type：Research paper (international conference proceedings) Publisher：4th International Conference on Electrical, Communication and Computer Engineering, ICECCE 2023

Currently, vehicles are equipped with various sensors that can collect a series of driving behavior data while driving. The driving behavior data obtained in this way can be used to analyze the causes of traffic accidents and evaluate driver skills. However, when performing the above analysis, a specific driving scene is defined and driving behavior data for that driving scene is required. On the other hand, the series of driving behavior data obtained during one driving operation is enormous, and it is not easy to pick up desired driving scene data from among them. This research aims to establish a driving scene clustering method for a series of driving behavior data. In this paper, a driving scene is defined as a scene in which road shape and operation are associated, and propose a driving scene clustering method considered road shape. Here, a road map image is acquired from position information obtained from a GPS sensor, and the relationship between the road map image and operation data is clustered based on Coupled-GP-HSMM.

DOI： 10.1109/ICECCE61019.2023.10442604

Capacitor Current Reduction in Dual Three-Phase PMSM Drive System by Model Predictive Control Considering Dead Time Reviewed International journal

Sakauchi R., Doki S., Imai K., Kondo K., Aoki Y.

2023 25th European Conference on Power Electronics and Applications, EPE 2023 ECCE Europe 2023

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：2023 25th European Conference on Power Electronics and Applications, EPE 2023 ECCE Europe

This paper proposes a novel capacitor current reduction method in Dual Three-Phase PMSM Drive System. By using Model Predictive Control considering the dead time on the premise of implementation, the method modifies the three-phase voltage command generated by the PI current controller for the current reduction. The effectiveness is verified by simulation and experiment.

DOI： 10.23919/EPE23ECCEEurope58414.2023.10264351

Arm-Mounted Assistive Robot for Measuring Contact Force and Evaluating Wearer Safety Reviewed International journal

Masaoka, S; Funabora, Y; Doki, S

IEEE ACCESS Vol. 11 page： 114855 - 114863 2023

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE Access

We developed a wearable assistive robot that directly measures the contact force acting between the robot and the human body, aiming to enhance the safety of such wearable devices. The force acting on the body is not directly measured, instead, it is estimated by measuring the torque acting on the robot joint in the wearable assistive robot. Despite the risk of failing to recognize dangerous forces due to modeling errors, the forces actually at work have not been examined. Here, we developed an arm-mounted assistive robot that directly measures the contact force as the distribution information to build a system and evaluate safety; in addition, the contact state between the robot and the human body was discussed. Accordingly, two experiments were conducted with 10 subjects. The first verified the contact force measurement performance of the robot, while the second demonstrated the application of contact force information to check the safety of the robot. The proposed robot can accurately measure the contact force, and the robot movement is safe under general control, for example, using the pain tolerance limit as the safety index. This eliminated the risk of not directly monitoring the forces acting on the surface of the human body. Furthermore, our result have implication for evaluating structural problems of the robot by evaluating contact conditions during movements.

DOI： 10.1109/ACCESS.2023.3324417

Application of Finite Control Set-Model Predictive Control for Servo Brake Motion in PMSM Drives Reviewed International coauthorship International journal

Kawai, H; Cordier, J; Kennel, R; Doki, S

IEEE CANADIAN JOURNAL OF ELECTRICAL AND COMPUTER ENGINEERING Vol. 46 ( 2 ) page： 117 - 129 2023

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE Canadian Journal of Electrical and Computer Engineering

Finite control set-model predictive control (FCS-MPC) has a simple and intuitive optimization procedure. Therefore, FCS-MPC is increasingly being applied to control strategies for electrical drive systems. This article presents a method for servo brake control of a permanent magnet synchronous motor (PMSM) based on FCS-MPC. Accordingly, we propose a reference trajectory introduced in a cost function for brake motions and an alternating procedure with speed control. Moreover, this article clarifies the problem peculiar to servo-brake control using FCS-MPC, i.e., the reduction in tracking performance near the brake position because of the low resolution of the output voltage. In addition to the conventional method, a finite number of smoothed voltages were applied as candidate voltages for FCS-MPC to improve the tracking performance near the brake position. The smoothed voltages can effectively increase the resolution of the output voltage, which results in fewer steady-state errors in angular position tracking during servo brake motion. The simulation and experimental results obtained using a PMSM drive system reveal that the proposed strategy exhibited high performance in tracking the reference target during the operation of servobrakes and the ability to seamlessly alternate between servo brake and motor operations.

DOI： 10.1109/ICJECE.2022.3233029

Modeling of Novel Dual Three Phase PMSM with Pseudo-Triple Winding Structure and its Current Vector Control Reviewed International journal

Aiba K., Doki S., Kato H., Isogai K.

2023 25th European Conference on Power Electronics and Applications, EPE 2023 ECCE Europe 2023

Language：English Publishing type：Research paper (international conference proceedings) Publisher：2023 25th European Conference on Power Electronics and Applications, EPE 2023 ECCE Europe

In this paper, we propose the control model for a novel dual three-phase PMSM with pseudo-triple winding structure(DTP-PMSM with PTWS) which is one of the new multiple stator winding machines. The proposed control model is represented as the extended form of the conventional dual three-phase winding machine, and the validity is demonstrated by being compared with magnetic field analysis results. Furthermore, the current vector controller for the control model is designed and its performance is confirmed by simulation.

DOI： 10.23919/EPE23ECCEEurope58414.2023.10264324

Performance Evaluation of Position Sensorless Control System with Initial Speed Estimator for Overall Speed Startup Reviewed International journal

Hao R., Doki S., Asahina K., Ide A.

2023 25th European Conference on Power Electronics and Applications, EPE 2023 ECCE Europe 2023

Language：English Publishing type：Research paper (international conference proceedings) Publisher：2023 25th European Conference on Power Electronics and Applications, EPE 2023 ECCE Europe

Position sensorless control for Permanent-magnet synchronous motors has been investigated in numerous studies, but the issues of flying start at high speed are still a major problem. In our previous research, the issues on conventional position control are presented, and the reasons for these issues are distinguished as the initial response of the speed estimation. Based on this discussion, an initial speed estimation method is proposed as a solution. In this paper, the whole position sensorless control system with the initial speed estimation is presented, which enables the startup from overall speed, and the evaluation experiments are reported.

DOI： 10.23919/EPE23ECCEEurope58414.2023.10264244

Optimal Current Control Methods for Single-Inverter Dual-Parallel-SPMSM with Different Parameters Reviewed International journal

Park, C; Doki, S

IEEJ JOURNAL OF INDUSTRY APPLICATIONS Vol. 12 ( 5 ) page： 961 - 970 2023

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：IEEJ Journal of Industry Applications

This paper presents optimal current-control methods for driving two different synchronous motors using a single inverter. When one inverter drives two motors, system efficiency will deteriorate if their loads are not identical. Moreover, even with identical loads, system efficiency will deteriorate if the parameters of the two motors are not identical. To address this issue, this paper proposes optimal current-control methods for systems with two different motors driven by a single inverter.

DOI： 10.1541/ieejjia.22010492

Optimal Current Control Methods for Dual-Parallel-SPMSM with Different Parameters Using a Single Inverter Reviewed International journal

Park C., Doki S.

ICPE 2023-ECCE Asia - 11th International Conference on Power Electronics - ECCE Asia: Green World with Power Electronics page： 211 - 220 2023

Language：English Publishing type：Research paper (international conference proceedings) Publisher：ICPE 2023-ECCE Asia - 11th International Conference on Power Electronics - ECCE Asia: Green World with Power Electronics

When one inverter drives both motors, the system efficiency deteriorates if both motors have different loads. Moreover, even if their loads are the same, the system efficiency would also deteriorate if the parameters of both motors are different. To address this issue, this paper proposes optimal current control methods for both different motors using a single inverter.

DOI： 10.23919/ICPE2023-ECCEAsia54778.2023.10213583

Position Sensorless Estimation for Surface Permanent Magnet Synchronous Motors Using Eddy Currents with Loads at a Low speed Reviewed International journal

Miki Y., Tomita M., Hasegawa M., Doki S.

2023 International Future Energy Electronics Conference, IFEEC 2023 page： 224 - 229 2023

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：2023 International Future Energy Electronics Conference, IFEEC 2023

Position sensorless control of surface permanent magnet synchronous motors (SPMSMs) in low-speed regions is challenging because the motor has no magnetic saliency. Several methods using the block commutation drive technique to overcome this problem have been proposed; however, the rotor position is estimated only every 60° owing to the features of the block commutation drive method. Therefore, in this study, we proposed a novel sensorless rotor position estimation method by pasting the conductive nonmagnetic materials on the rotor. When high-frequency voltage is applied, eddy currents flow through the materials and the inductance slightly changes depending on the rotor position. In this study, estimating the continual rotor position from 0° to 360°, in which the sinusoidal vector control commutation is necessary rather than the block commutation drive method, was realized using these inductance changes. Based on the experimental results, we found that the rotor position could be continually estimated from 0 to 360°, which is necessary for sinusoidal vector commutation for an SPMSM with a position estimation error of approximately 6°, although the rotor velocity was low at 1.59 % of the rated velocity and 12 % of the rated load was applied.

DOI： 10.1109/IFEEC58486.2023.10458604

Turning a Functional Cloth Into an Actuator by Combining Thread-Like Thin Artificial Muscles and Embroidery Techniques Reviewed International journal

Nakagawa, K; Sakai, Y; Funabora, Y; Doki, S

IEEE ROBOTICS AND AUTOMATION LETTERS Vol. 7 ( 3 ) page： 5827 - 5833 2022.7

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE Robotics and Automation Letters

In this letter, we propose to turn various existing cloths, especially functional cloths, into actuators by combined embroidery technology and thin McKibben artificial muscles. Most of the textile sensors so far are made by weaving active yarns into each other or into other base cloths. These devices have a limited choice of cloths that can be actuated. We create a prototypical actuator that can be deformed in three dimensions using thin artificial muscles and embroidery techniques on a functional cloth used for hook-and-loop fasteners and textiles that can observe pressure. Our experimental results indicate that the force of the artificial muscles can be transmitted to the cloth using fixation by embroidery and that the actuator can be variously deformed in three dimensions. We show that functional cloths can be made into actuators while maintaining their own functions using the proposed method.

DOI： 10.1109/LRA.2022.3157401

Basic Verification of Contact Force-Based Control with Full Body-Worn Assistive Robot Reviewed International journal

Masaoka S., Funabora Y., Doki S.

2022 IEEE/SICE International Symposium on System Integration, SII 2022 page： 144 - 149 2022.1

Language：English Publishing type：Research paper (international conference proceedings) Publisher：2022 IEEE/SICE International Symposium on System Integration, SII 2022

This paper evaluates the performance of contact force-based control with developed wearable assistive robots enabling the contact force measurement between the wearer and the robot. Almost all the conventional assistive robots are controlled with their joint torque measured via torque sensors. These robots have risks exerting excessive force on the wearer because torque sensors cannot detect contact force exerting the wearer. Our research group developed the contact force-based control and evaluated its performance only on the simulation. Also, we developed a prototype of a wearable robot enabling to measure and detect the contact force. In this paper, tracking performance to the wearer's movements, one of the basic performances of wearable robots, is confirmed via the experience. As a result, contact force-based control can operate in full accordance with the command of zero contact force.

DOI： 10.1109/SII52469.2022.9708851

Current Control System with High-Frequency Signal Injection for Dual Three-Phase Permanent Magnet Synchronous Motor Reviewed International journal

Imai, K; Doki, S; Kondo, K; Aoki, Y

IEEJ JOURNAL OF INDUSTRY APPLICATIONS Vol. 11 ( 1 ) page： 27 - 40 2022

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：IEEJ Journal of Industry Applications

Dual three-phase permanent magnet synchronous motors have the characteristics of multi-phase and permanent magnet synchronous motors, whose double- and decoupled-winding models based on the vector space decomposition have been reported. High-frequency signal injection methods enable position sensorless control, parameter identification, and the search for maximum torque per ampere operating points. However, the current control system with high-frequency signal injection for a dual three-phase permanent magnet synchronous motor has not yet been sufficiently discussed. This study compares the double- and decoupled-winding models for the current control system with the high-frequency signal injection and proposes a current control system with high-frequency signal injection. Furthermore, this study proposes a position sensorless control method at low speed based on the high-frequency voltage injection as an application of the proposed current control system with the high-frequency signal injection. Experiments verify the effectiveness of the proposed current control system with the high-frequency signal injection and the proposed position sensorless control method.

DOI： 10.1541/ieejjia.20012955

AR Image Presentation based on Gaze Information for Operator support in teleoperation Reviewed International journal

Doki K., Funabora Y., Doki S., Yano Y.

SAMI 2022 - IEEE 20th Jubilee World Symposium on Applied Machine Intelligence and Informatics, Proceedings page： 395 - 400 2022

Language：English Publishing type：Research paper (international conference proceedings) Publisher：SAMI 2022 - IEEE 20th Jubilee World Symposium on Applied Machine Intelligence and Informatics, Proceedings

The authors have been tackling a new teleoperation system with a head-mounted display (HMD) and an omnidirectional camera to reduce the workload of an operator. Some experimental results verified that presentation of AR images based on sensor information could reduce the workload and prevent the deterioration of the task quality due to the transmission delay of images. However, the range of the field of view (FOV) of an HMD is narrower than that of a human. This difference might cause accidents by overlooking hazards that are outside the FOV of the HMD. To solve this problem, the authors propose a new method of AR image presentation based on gaze information not to overlook hazards. Some experimental results using a driving simulator verified the usefulness of the proposed method.

DOI： 10.1109/SAMI54271.2022.9780732

Stability Improvement Method of Position Sensor less Control for Single Inverter Dual Parallel IPMSMs Drive System by Using Signal Injection Reviewed International journal

Park C., Doki S.

2022 International Power Electronics Conference, IPEC-Himeji 2022-ECCE Asia page： 583 - 588 2022

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：2022 International Power Electronics Conference, IPEC-Himeji 2022-ECCE Asia

This paper proposes a method to drive a single-inverter dual interior permanent magnet synchronous motor (IPMSM) system by using signal injection. Considerable research has been performed to decrease the size and cost of dual motor drive systems by driving two synchronous motors with one inverter. In general, the control is implemented considering one of the two motors. Such systems may become unstable because of the mechanical/electrical resonance occurring in the uncontrolled motor. Therefore, methods to suppress this resonance have been established. Notably, resonance control is challenging to implement at low speeds because the phase of the rotor with sensorless control cannot be easily estimated. To address this problem, signal injection and signal processing methods for such systems was established in this study.

DOI： 10.23919/IPEC-Himeji2022-ECCE53331.2022.9806970

Performance Evaluation of Startup and Driving Strategy at Overall Speed with Extended ElectroMotive Force for Position Sensorless Permanent Magnet Synchronous Motor Reviewed International journal

Hao R., Kozakura T., Doki S.

2022 International Power Electronics Conference, IPEC-Himeji 2022-ECCE Asia page： 362 - 367 2022

Authorship：Corresponding author Language：Japanese Publishing type：Research paper (international conference proceedings) Publisher：2022 International Power Electronics Conference, IPEC-Himeji 2022-ECCE Asia

Extended electro-motive force (EEMF) estimation method is a fast position estimation method used for overall speed. In our previous research, we have reported the startup and drive method with EEMF from standstill. However, starting a free-running PMSM, which is known as the flying start, is rarely taken into consideration in the most position sensorless research. Under such condition, the rotor speed is unobservable before the startup. In this paper, a startup and driving strategy at overall speed with EEMF by speed and signal injection is proposed, and the evaluation experiments are reported.

DOI： 10.23919/IPEC-Himeji2022-ECCE53331.2022.9806847

Operator Assistance for Remote Driving with Augmented Image based on Gaze Information Reviewed International journal

Dokil K., Suzuki K., Funabora Y., Doki S., Yano Y.

IEEE International Symposium on Industrial Electronics Vol. 2022-June page： 1094 - 1099 2022

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE International Symposium on Industrial Electronics

The authors have been aiming to realize a remote driving system with an HMD(Head Mounted Display) and a 360-degree camera to decrease the task load of the operator. Therefore, we have been tackling an operator assistance method of remote driving applying Augmented Reality(AR). In the previously proposed methods, AR video presented to the operator is generated based on sensing information of 3D LiDAR to deal with the communication delay. In this paper, a new generation method of AR image is proposed, in which Gaze information of the operator is used to create a 3D object to draw his attention to a hazard that might cause a traffic accident. The usefulness of the proposed method has been evaluated based on the results of the experiments using a driving simulator which has a scenario of a person jumping out from a park.

DOI： 10.1109/ISIE51582.2022.9831663

Motor Drive Method that Enlarges the Applied Voltage without Causing High Harmonics under the Voltage Supply Unbalance in Three Phase Dual Winding Permanent Magnet Motor Reviewed International journal

Suzuki Takashi, Doki Shinji

IEEJ JOURNAL OF INDUSTRY APPLICATIONS Vol. 11 ( 3 ) page： 506 - 513 2022

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：IEEJ Journal of Industry Applications

To realize automated drive of a vehicle, more reliability to the motor drive system is required. The three phase dual winding permanent magnet motor drive using two inverters with corresponding voltage supplies is one of the potential candidates for the reliable motor drive system. With the respective voltage supply and winding connected to the inverter, the two motor drive systems are electrically independent. Thus, even if when a failure occurs in one of the systems, the other system can continue the motor drive. However, there is an issue: a voltage drop in one of the voltage supplies reduces the sinusoidal wave region of the drive system as the rotor of the motor is common in the two windings and the back electromotive voltage in the two windings are the same. The motor drive method that enlarges the applied voltage without causing high harmonics under the voltage supply unbalance in the three phase dual winding permanent magnet motor is proposed in this paper.

DOI： 10.1541/ieejjia.21009935

Implementation of Vector Control System On Multi-Core Processor by Using Model-Based Parallelization Tool Reviewed International journal

Kim J., Sagae S., Edahiro M., Honda S., Doki S.

2022 International Power Electronics Conference, IPEC-Himeji 2022-ECCE Asia page： 1314 - 1319 2022

Language：English Publishing type：Research paper (international conference proceedings) Publisher：2022 International Power Electronics Conference, IPEC-Himeji 2022-ECCE Asia

According to the increase in the required performance of the product, a multi-core processor that can process tasks simultaneously is attracting attention. To efficiently utilize a multi-core processor, a Model-Based Parallelization Tool(MBP) technology has been proposed to automatically generate paral-lelization code in consideration of the causal relationship of the control system. However, parallel processing time and control performance verification in real systems have not been sufficiently investigated. In this paper, to verify the validity of the parallelization code automatically generated by the MBP on a real system, we compare and review the single-code of the function unit by hand and the parallel code automatically generated by the MBP. In addition, we verify the MBP Tool by analyzing parallelization results as well as points to consider when implementing a motor control system.

DOI： 10.23919/IPEC-Himeji2022-ECCE53331.2022.9807202

Current Vector Control System Based on a New Discrete dq-Axis IM Model for High Speed Drive Reviewed International journal

Takeuchi T., Doki S.

2022 International Power Electronics Conference, IPEC-Himeji 2022-ECCE Asia page： 783 - 788 2022

Authorship：Corresponding author Language：Japanese Publishing type：Research paper (international conference proceedings) Publisher：2022 International Power Electronics Conference, IPEC-Himeji 2022-ECCE Asia

In this paper, we propose a novel discrete current control scheme for IM (Inductive Motor). Ordinary, a current vector controller is designed by using the dq-axis model, which is induced under the assumption that Park transformation is continuously performed, and the designed controller is discretely implimented. If the sampling period is not short enough compared to the voltage supply frequency during high speed drive, these assumptions do not hold, and the control performance of the current system is greatly degraded, which results in control failure. To solve this problem, we proposed a discrete dq-axis IM model which is effective for low control period and high speed drive, and designed a current vector controller based on this model to improve control performance at high speed drive and confirmed the effect in simulation.

DOI： 10.23919/IPEC-Himeji2022-ECCE53331.2022.9807157

Control Method of Dual Parallel Surface-Mounted Permanent-Magnet Synchronous Motor Systems with Different Parameters Using Single Inverter Reviewed International journal

Park C., Doki S.

2022 IEEE Energy Conversion Congress and Exposition, ECCE 2022 2022

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：2022 IEEE Energy Conversion Congress and Exposition, ECCE 2022

This paper presents a control method for different dual-parallel-SPMSMs systems with a single inverter. Disturbance causes a torque difference between the two motors when one inverter drives two SPMSMs. This may lead to the motor's mechanical and electrical resonance. Several damping control methods have been proposed to suppress this resonance. However, such methods consider that the parameters of the two motors are identical. When one inverter controls two motors with different parameters, the damping control performance deteriorates. Additionally, the motor's resonance sound and motor current ripple increase. To solve these problems, this paper proposes a control method for dual parallel Surface Permanent Magnet Synchronous Motor (SPMSM) drive systems with a single inverter.

DOI： 10.1109/ECCE50734.2022.9947789

Modeling Fabric-Type Actuator Using Point Clouds by Deep Learning Reviewed International journal

Peng, YH; Yamaguchi, H; Funabora, Y; Doki, S

IEEE ACCESS Vol. 10 page： 94363 - 94375 2022

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE Access

Flexible actuators are popular in the consumer and medical fields because of their flexibility and compliance. However, they are typically difficult to model because of their viscoelasticity and nonlinearity. This letter proposes a method for correcting the deformation of the simulated flexible robots to make it similar to the deformation of real robots using point clouds by deep learning. Long short-term memory (LSTM) can simulate the next frame of actuator deformation from the previous frames of deformations. In this study, we presented the robots with four different muscle structures. We found that using an encoder-LSTM-decoder network can improve the similarity between the deformation of a learned muscle structure and the real deformation and is also effective in correcting the deformation of the unlearned structures. Our correction method reduced the average Chamfer distance of the simulated point clouds of the basic-type structure actuator from 15.89 to 7.81. This research can provide a new concept for future flexible robot modeling using point clouds.

DOI： 10.1109/ACCESS.2022.3204652

Decoupled Current Vector Control of Dual Three Phase PMSM Drives with Two Independent Micro Control Units Utilizing Current Observer Reviewed International journal

Wang, S; Doki, S; Suzuki, T; Fujii, K; Hayashi, Y

IEEJ JOURNAL OF INDUSTRY APPLICATIONS Vol. 11 ( 6 ) page： 779 - 789 2022

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：IEEJ Journal of Industry Applications

This paper presents a coupling estimation based decoupled current vector control scheme for current control of a Dual Three Phase (DTP) Surface Permanent Magnet Synchronous Motor (SPMSM) drive with two micro control units (MCUs), to solve its inherent magnetic coupling issue. Aiming for an enhanced fault tolerance, the SPMSM drive utilized is a redundant and modular system composed of two subsystems in terms of three-phase inverters, sensing, and controllers, with respect to each winding set in the DTP SPMSM. The current of each winding set along with the rotor position is separately detected and applied for control by individually assigned MCU. This comprehensive modularity prevents interference between subsystems in local fault conditions, thus improving the fault tolerance capability. However, the magnetic coupling existing between the winding sets would deteriorate the performance and even cause instability in the whole system without proper decoupling control. Previous studies adopted communication between MCUs for real time current sampling sharing demanded by decoupling control. Nevertheless, communication bandwidth becomes a limiting factor of system design. Some general communication approaches would not satisfy the current sharing requirement of decoupling control for implementation. To eliminate this undesirable limit, a novel decoupled current vector control that utilizes a current observer to estimate the relevant magnetic coupling between winding sets is proposed in this paper. As validated from the experiment results, the proposed decoupled control scheme is able to decouple the system for dynamic improvement so that modularity of the drive can be achieved without communication, leading to an eventual improvement in fault tolerance capability.

DOI： 10.1541/ieejjia.22000073

Multisensor robust localization in various environment with correlation checking test Reviewed International journal

Ohashi N., Funabora Y., Doki S., Doki K.

ROBOMECH Journal Vol. 8 ( 1 ) 2021.12

Language：English Publishing type：Research paper (scientific journal) Publisher：ROBOMECH Journal

Probabilistic localization based on Bayesian theory has been researched as a sensor fusion method to improve the robustness of localization. Pieces of position information, generated by sensors’ observation models with consideration for noises, are fused according to Bayesian theory. However, having large noises not considered in their observation models, the sensors output erroneous position information; thus, the fusion result has a significant error, even when the other sensors output correct ones. In this research, we have proposed a sensor fusion system with a relative correlation checking test to realize robust localization. Pieces of erroneous position information, biased against others and having a negative correlation with others, are detected and excluded in our proposed system by checking their correlation between all of them. The purpose of this paper is to evaluate the robustness of our fusion system by conducting recursive localization experiments in various environments.

DOI： 10.1186/s40648-021-00190-9

Effects of Inductance Error on Position Sensorless Control of Synchronous Reluctance Motor at Low Speeds Using High-Frequency Current Controller Reviewed International journal

Hayashi T., Kataoka K., Tomita M., Hasegawa M., Doki S.

IEACon 2021 - 2021 IEEE Industrial Electronics and Applications Conference page： 91 - 96 2021.11

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEACon 2021 - 2021 IEEE Industrial Electronics and Applications Conference

Synchronous reluctance motors (SynRMs) have attracted attention for various applications because they have no magnets and rotor windings. Thus, various methods for rotor position sensorless control of SynRMs at low speeds have been proposed. Similarly, we previously introduced a method for rotor position sensorless control of SynRMs at very low speeds. The proposed control method superimposes a high-frequency current with a small constant amplitude using a high-frequency current control system. The q-axis inductance of the SynRM considerably changes according to the load. In this paper, we show that the rotor position estimation error converges even under a large error between the predefined and real settings of the q-axis inductance of the SynRM model for position estimation when using the proposed method. Experimental results confirm that the proposed method achieves robust rotor position sensorless control against q-axis inductance variations even at very low speeds.

DOI： 10.1109/IEACon51066.2021.9654631

Capacitor Current Reduction of Double Three Phase PMSM Drive System by Real-time MPC Reviewed International journal

Suzuki A., Doki S., Imai K., Aoki Y., Kondo K.

IECON Proceedings (Industrial Electronics Conference) Vol. 2021-October 2021.10

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IECON Proceedings (Industrial Electronics Conference)

This paper proposes a capacitor current reduction method using real-time model predictive control (MPC) for a double three-phase permanent magnet synchronous motor (DTPPMSM) drive system. Capacitor current reduction for volume minimization of DTP-PMSM drive system is important issue. Optimizing switching timings by MPC is promising approach. However, it is difficult to implement ideal MPC in a real system because it requires a huge amount of calculation to predict the capacitor current. In this paper, we propose a new method that is possible to search optimal switching timing for reducing the capacitor current by using the MPC, whose calculation amount can be implemented in real-time. This paper shows the possibility of realizing an capacitor current reduction method with high control performance by reducing the amount of computation for MPC.

DOI： 10.1109/IECON48115.2021.9589070

AR Image Presentation Based on Sensor Data for Operator Support in Remote Car Driving : -Aiming for Remote Car Driving Reviewed International journal

Doki K., Suzuki K., Yano Y., Funabora Y., Doki S.

2021 IEEE 10th Global Conference on Consumer Electronics, GCCE 2021 page： 774 - 776 2021.10

Language：English Publishing type：Research paper (scientific journal) Publisher：2021 IEEE 10th Global Conference on Consumer Electronics, GCCE 2021

In order to realize a remote car driving in an emergency situation or complicated environment, we propose a new method for operator support in teleoperation in this paper. In the proposed teleoperation system, it is supposed that there are two communication lines between an operator and the target remote driving car. The one is called as the main line, in which large data like image or sound are transferred allowing a large delay. The other is called as the subline, in which small data like emergency signals are transferred with a small delay. In the proposed method, an AR image is presented to an operator, in which 3D objects superimposed on a real image are generated using sensor data transferred through the subline. Due to the 3D objects with a small delay on a real image with a large delay, the operator can safely control the target car even if the image has an enormous delay caused by the bad communication status.

DOI： 10.1109/GCCE53005.2021.9622070

A Novel Decoupling Control of Dual Three Phase Drive with Two Independent Microprocessors Utilizing Current Observer Reviewed International coauthorship

Shen Wang, Kentaro Kitamura, Shinji Doki, Takashi Suzuki

Proceedings of the applied power electronics conference (APEC 2021) 2021.6

Human Action Modeling Method based on the Causality between a Sitution and an Action Reviewed

Kae Doki, Kohjiro Hashimoto, Yuki Funabora, Shinji Doki, Akihiro Torii

IEEJ Transactions on Electronics, Information and Systems Vol. 141 ( 2 ) page： 193 - 204 2021.2

AR video presentation using 3D LiDAR information for operator support in mobile robot teleoperation Reviewed International coauthorship International journal

Doki K., Suzuki K., Torii A., Mototani S., Funabora Y., Doki S.

SAMI 2021 - IEEE 19th World Symposium on Applied Machine Intelligence and Informatics, Proceedings page： 59 - 64 2021.1

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：SAMI 2021 - IEEE 19th World Symposium on Applied Machine Intelligence and Informatics, Proceedings

In this paper, we propose a new teleoperation system of a mobile robot using Augmented Reality(AR) based on 3D LiDAR information for operator support. In the proposed system, an 360-degree camera is equipped with a robot which works in a remote place controlled by an operator, and the captured 360-degree image is displayed to the head mounted display put on the head of the operator. The operator can smoothly control the robot watching what he needs for his task by turning his head. In addition, the provided image around the robot has no blind spot because of the 360-degree image. However, the data size of the 360-degree image is enormous and it causes a large transfer delay or dropped frames which adversely influence the operator performance. In order to solve this problem, it is proposed that an AR image is actually provided to the operator, in which objects generated based on 3D LiDAR information are superimposed on the 360-degree image as AR objects. In this paper, the usefulness of the proposed method is shown through the experimental results on parking the robot remotely.

DOI： 10.1109/SAMI50585.2021.9378687

Fault Tolerant Asymmetrical Six Phase Drive Controlled by Two Microprocessors Reviewed

Shen Wang, Kentaro Kitamura , Shinji Doki, Takashi Suzuki, Norihisa Ito, Yoshitaka Hayashi

Proceedings of The 5th International Electric Vehicle Technology Conference EVTeC 2021 2021

Control Method that Reduces the High Harmonic in the Overmodulation Drive of the Dual Winding Motor during Voltage Supply Unbalance Reviewed International journal

Suzuki, T; Doki, S

IEEJ JOURNAL OF INDUSTRY APPLICATIONS Vol. 10 ( 6 ) page： 770 - 778 2021

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：IEEJ Journal of Industry Applications

More reliable motor drive systems are expected in the realization of automated driving. The redundant motor drive system with two voltage supplies, two inverters, and a dual winding motor is one of the strong candidates since the two systems that construct the motor drive system are electrically independent. The dual winding motor has a characteristic of cancelling the 6th harmonic produced in the overmodulation drive. However, it loses its characteristic when there is a voltage difference in the two voltage supplies. In this paper, it is proposed to control only the sum of the current during the overmodulation to maintain the characteristic of cancellation even if there is voltage difference in the two voltage supplies. Furthermore, the current difference of the two windings is controlled in the sinusoidal wave region to suppress the deviation of currents and turned off during the overmodulation to reduce 6th harmonic. The maintained characteristic during voltage supply unbalance is confirmed with the experiment.

DOI： 10.1541/ieejjia.21001387

Model Predictive Current Control of PMSM drives for Achieving both Fast Transient Response and Ripple Suppression Reviewed International coauthorship International journal

Kawai Hiroaki, Cordier Julien, Kennel Ralph, Doki Shinji

IECON 2021 - 47TH ANNUAL CONFERENCE OF THE IEEE INDUSTRIAL ELECTRONICS SOCIETY 2021

Maximum Torque Minimum Peak Phase Current of a Dual Winding Interior Permanent Magnet Synchronous Motor Reviewed International journal

Suzuki, T; Otake, H; Doki, S

IEEJ JOURNAL OF INDUSTRY APPLICATIONS Vol. 10 ( 1 ) page： 11 - 17 2021

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：IEEJ Journal of Industry Applications

This paper presents an analysis of the maximum torque minimum peak phase current of the dual winding interior permanent magnet motor. Reducing the current contributes to small motor size. The peak phase current to generate the torque is reduced by the cancelation of the torque ripple generated by the two windings. The high harmonic current that does not generate torque ripple in the dual winding motor is analyzed. With the high harmonic current, the minimum peak phase current to generate a predetermined torque is calculated. The experiments were conducted to confirm the reduction of the peak phase current without increasing the torque ripple.

DOI： 10.1541/ieejjia.20000098

Control Method that Reduces the High Harmonic in Overmodulation Drive of Dual Winding Motor under Condition of Voltage Supplies Unbalance Reviewed

Suzuki T., Doki S.

23rd International Conference on Electrical Machines and Systems, ICEMS 2020 page： 918 - 923 2020.11

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：23rd International Conference on Electrical Machines and Systems, ICEMS 2020

Looking toward the autonomous driving, redundant motor drive system with two voltage supplies, two inverters, and a dual winding motor is reported recently. The dual winding motor has a characteristic of cancelling the 6th harmonic produced in overmodulation drive. However, it loses its characteristic when there is voltage difference in the two voltage supplies. In this report, it is shown that characteristics of cancellation is maintained even if there is voltage difference in the two voltage supplies when sum of the current is controlled. The maintained characteristics is confirmed with the simulation.

DOI： 10.23919/ICEMS50442.2020.9290790

The improvement of initial rotor position estimation method with Extended-EMF available at overall speed range by exciting with speed and signal injection Reviewed

Kozakura T., Nimura T., Doki S.

23rd International Conference on Electrical Machines and Systems, ICEMS 2020 page： 252 - 257 2020.11

Language：English Publishing type：Research paper (scientific journal) Publisher：23rd International Conference on Electrical Machines and Systems, ICEMS 2020

We have proposed position sensorless control of PMSMs with Extended-ElectroMotive Force(EEMF). It is available at overall speed with a single estimator by exciting with speed and signal injection. Therefore, the configuration is simplified, and acceleration/deceleration rate is improved because a controller is not switched to another. Additionally, Extended-EMF also available for the start-up method which uses principle of magnetic saturation. In this paper, we propose the new initial rotor position estimation method using Extended-EMF.

DOI： 10.23919/ICEMS50442.2020.9291103

Examination of Magnetization Curve Model for Torque Ripple Reduction of IPMSMs to Compensate for Magnetic Characteristics Reviewed

Akatsuka H., Hasegawa M., Doki S.

23rd International Conference on Electrical Machines and Systems, ICEMS 2020 page： 240 - 245 2020.11

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：23rd International Conference on Electrical Machines and Systems, ICEMS 2020

This paper evaluates a torque ripple reduction performance of IPMSMs by model selection of magnetization curves to be compensated for magnetic characteristics. A non-linearity compensation method for magnetic characteristics has been proposed, which is based on simple approximations of the magnetization curve. Therefore, an approximation of the magnetic characteristics suitable for torque ripple reduction was studied and the performance of the proposed method was experimentally evaluated.

DOI： 10.23919/ICEMS50442.2020.9290817

Examination of Current Sensor Fail-Safe of PMSM current control system which using current and position state estimation techniques Reviewed

Hori S., Doki S.

23rd International Conference on Electrical Machines and Systems, ICEMS 2020 page： 694 - 698 2020.11

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：23rd International Conference on Electrical Machines and Systems, ICEMS 2020

PMSM is increasingly used in applications requiring safety, such as electric vehicles. However, in a typical PMSM drive system, just one failure of the sensors causes whole system failure. Then it is focused on the potential to improve the system redundancy by making the sensing system redundant In this paper, we report that the control of a current sensing system made redundant by state estimation techniques can be continued even in the event of a phase current sensor failure.

DOI： 10.23919/ICEMS50442.2020.9290924

A Novel Decoupling Control Scheme for Dual Three Phase Motors Reviewed International journal

Wang S., Imai K., Doki S.

23rd International Conference on Electrical Machines and Systems, ICEMS 2020 page： 1225 - 1229 2020.11

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：23rd International Conference on Electrical Machines and Systems, ICEMS 2020

A novel decoupling control scheme for multiphase machines with multiple three-phase winding sets, for instance, the Dual Three Phase (DTP) machines, is proposed in this paper. This motor has two sets of three phase windings that implemented spatially with 30 electrical degrees. Vector Space Decomposition (VSD) frame and Multiple Stator (MS) frame are well known for its vector control. VSD frame has been applied in many applications due to its clear harmonics mapping and good extensions to multiphase machines. On the other hand, MS frame is more intuitive as to treat two winding sets individually so that the accumulated techniques of three-phase machines can be applied directly. However, this approach was not adopted in high performance drives because its decoupling control methodology is not sufficiently developed to solve its inherent magnetic coupling issue. Therefore, this paper proposed a decoupling control scheme to improve dynamic performance of MS frame, and performance has been evaluated by experimental results.

DOI： 10.23919/ICEMS50442.2020.9290999

Position Sensorless Estimation for Surface Permanent Magnet Synchronous Motor Using Eddy Current Reviewed International journal

Kato S., Tomita M., Hasegawa M., Doki S.

23rd International Conference on Electrical Machines and Systems, ICEMS 2020 page： 1972 - 1976 2020.11

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：23rd International Conference on Electrical Machines and Systems, ICEMS 2020

The rotor position sensorless control of Surface Permanent Magnet Synchronous Motor (SPMSM) at a standstill and in the low-speed region is challenging because the motor has no magnetic saliency. Thus, the paper presents the development of a new rotor position-sensorless estimation method for SPMSM.In the proposed method, thin conductive non-magnetic materials are placed on the rotor surface. When the high-frequency voltage is applied, the eddy current flows through the materials, and the inductance is slightly changed depending on the rotor position. The position estimation from 0 to 360 angles (electrical degrees) where the field-oriented control (FOC) is required for SPMSM is realized using this inductance changes. The experiments show that the initial rotor position estimation error is less than 20 degrees ; thus, the proposed method is very useful.

DOI： 10.23919/ICEMS50442.2020.9291246

Performance Evaluation of Position Sensorless Control by using Extended Electromotive Force including Overmodulation Region on Electric Vehicle Reviewed International journal

Kitamura K., Doki S.

23rd International Conference on Electrical Machines and Systems, ICEMS 2020 page： 550 - 554 2020.11

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：23rd International Conference on Electrical Machines and Systems, ICEMS 2020

Position sensorless control of PMSMs is one of the important research object in terms of lowering cost, saving installation space and improvement of reliability. A previous research proposed a method to estimate EEMF(Extended Electromotive Force) excited by signal injection and speed for all speed range and confirmed its performance in EV. In this paper, position sensorless control including overmodulation is implemented to EV and evaluated its performance.

DOI： 10.23919/ICEMS50442.2020.9291125

A Study on the Implementation of Vector Control System Using the Model Base Parallelization Tool on Multi-Core Processor Reviewed International journal

Kim J., Kato S., Honda S., Edahiro M., Doki S.

23rd International Conference on Electrical Machines and Systems, ICEMS 2020 page： 1951 - 1956 2020.11

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：23rd International Conference on Electrical Machines and Systems, ICEMS 2020

The scope of embedded systems used by multi-core processors is widely applied to various products that require control, such as home appliances, industrial devices, transportation devices, and communication terminals. Model-Base Parallelization technology was proposed towards efficient parallelization to implement a control system in the introduction of multi-core processors. By applying MBP, it is possible to parallelization even details that people are not aware of, but the control system with numerous causal relationships still does not sufficiently utilize multi-core. Therefore, a method of inserting a time-delay is being studied as a method for improving the parallelization of multi-cores.In this paper, We describe the insertion location that improves parallelization and does not affect the control performance by inserting time-delay to implement the vector control system of PMSM on multi-core efficiently.

DOI： 10.23919/ICEMS50442.2020.9290965

Design Method of Model Predictive Control for Development of Current Control System of PMSM Reviewed

Shimaoka M., Doki S.

IEEJ Transactions on Industry Applications Vol. 140 ( 11 ) page： 793 - 806 2020.11

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：IEEJ Transactions on Industry Applications

This paper describes the design method for Model Predictive Control (MPC) that is suitable for current control systems of Permanent Magnet Synchronous Motor (PMSM). A current control system based on MPC predicts future current behaviors for considerable input voltage and determines the optimum input voltage by evaluating these behaviors. Conventional MPC sets the cost function, making it effective for several control purposes. However, the suitability of the search space of conventional MPC has not been discussed and its achievable performance was limited. In this paper, we consider an appropriate search space for current control system of PMSM by referring to existing modulation methods and inverter operation. Then, we propose new MPC that satisfies that search space and show that the proposed MPC can usage from a linear region to a square-wave region by the appropriate search space.

DOI： 10.1541/ieejias.140.793

PMSM電流制御系構築のためのモデル予測制御の設計法 Reviewed

嶋岡雅浩, 道木慎二

電気学会論文誌D Vol. 140 ( 11 ) page： 793-806 2020.11

PMSM電流制御系構築のためのモデル予測制御の設計法 Reviewed

嶋岡雅浩, 道木慎二

電気学会論文誌D Vol. 140 ( 11 ) page： 793-806 2020.11

Servo brake control based on finite control set-model predictive control with a voltage smoother Reviewed International coauthorship International journal

Kawai H., Cordier J., Kennel R., Doki S.

Proceedings - 2020 IEEE 2nd Global Power, Energy and Communication Conference, GPECOM 2020 page： 131 - 136 2020.10

Language：English Publishing type：Research paper (international conference proceedings) Publisher：Proceedings - 2020 IEEE 2nd Global Power, Energy and Communication Conference, GPECOM 2020

This study presents an angular position control strategy for servo brake motion of an electric motor based on a finite control set-model predictive control (FCS-MPC) with a voltage smoother. In the proposed control scheme, the controller predicts the future current, speed and angular position with a finite set of smoothed voltages and outputs the optimal smoothed voltage by using pulse width modulation (PWM). Smoothed voltages effectively reduce current ripple, which results in less parasitic oscillations of the angular position while tracking the reference target. The simulated and experimental results obtained with a permanent magnet synchronous motor (PMSM), fed by a 2-level 3-phase voltage source inverter, show that the proposed method has both excellent performance of current ripple reduction and excellent dynamic performance in servo brake motion.

DOI： 10.1109/GPECOM49333.2020.9247941

Torque Ripple Reduction of IPMSM Considering Compensation of Nonlinearities of Magnetic Characteristics Reviewed

Akatsuka H.

IECON Proceedings (Industrial Electronics Conference) Vol. 2020-October page： 1102 - 1107 2020.10

信号重畳と速度により励起される拡張誘起電圧を利用した永久磁石同期モータの全速度域位置センサレス制御 Reviewed

二村拓未, 道木慎二

電気学会論文誌Ｄ Vol. 140 ( 8 ) page： 8589-596 2020.8

信号重畳と速度により励起される拡張誘起電圧を利用した永久磁石同期モータの全速度域位置センサレス制御 Reviewed

二村拓未, 道木慎二

電気学会論文誌Ｄ Vol. 140 ( 8 ) page： 8589-596 2020.8

モデル予測制御に基づくPMSM電流制御系の定常電流制御性能改善のための探索空間設計 Reviewed

嶋岡雅浩, 道木慎二

電気学会論文誌D Vol. 140 ( 6 ) page： 468-479 2020.6

モデル予測制御に基づくPMSM電流制御系の定常電流制御性能改善のための探索空間設計 Reviewed

嶋岡雅浩, 道木慎二

電気学会論文誌D Vol. 140 ( 6 ) page： 468-479 2020.6

Position sensorless control of PMSM at overall speed with extended-EMF excited by speed and signal injection Reviewed

Nimura T., Doki S.

IEEJ Transactions on Industry Applications Vol. 140 ( 8 ) page： 589 - 596 2020

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEJ Transactions on Industry Applications

Extended electromotive force (EEMF) estimation method is a representative method used for position sensorless control of PMSM in the middle/high speed range. EEMF enables position estimation by utilizing back-EMF and the saliency of inductance. The amplitude of EEMF is adjusted to maintain it above a certain voltage by using a signal injection, regardless of the rotor speed. Thus, EEMF can be used as a single position estimator to estimate overall speed range. Based on the validation of a EEMF control performance and a parameter sensitivity analysis, this paper presents a position sensorless control system configured with a single position estimator from startup to middle/high speed. The necessary adjustment parameter and control performance of the actual machine are also presented.

DOI： 10.1541/ieejias.140.589

Design of Search Space for Improving the Steady Current Control Performance of PMSM Current Control System based on Model Predictive Control Reviewed International journal

Shimaoka M., Doki S.

IEEJ Transactions on Industry Applications Vol. 140 ( 6 ) page： 468 - 479 2020

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：IEEJ Transactions on Industry Applications

This paper proposes a method to design the search space of Model Predictive Control (MPC) for improving the steady current control performance of Permanent Magnet Synchronous Motor (PMSM) current control system. A current control system based on MPC predicts the future current behaviors for considerable input voltage and determines the optimum input voltage by evaluating these behaviors. However, the basic MPC has inferior steady current control performance depending on the operating points. This is because the search space of basic MPC represented by voltage vectors is not suitable appropriate for PMSM current control. To overcome this problem, we consider difference of search space of basic MPC and current vector control with a modulator such as Pulse Width Modulation (PWM) or Space Vector Modulation (SVM) and clarify the necessary search space for improving the steady current control performance. Then we propose a design method for the search space, and through experimentation, we show that proposed design method can improve the steady current control performance.

DOI： 10.1541/ieejias.140.468

Position Sensorless Control of Synchronous Reluctance Motors at Low-Speeds Reviewed International coauthorship International journal

Hatanaka T., Kato S., Tomita M., Hasegawa M., Doki S., Kato S.

2019 IEEE 4th International Future Energy Electronics Conference, IFEEC 2019 2019.11

Language：English Publishing type：Research paper (scientific journal) Publisher：2019 IEEE 4th International Future Energy Electronics Conference, IFEEC 2019

Synchronous reluctance motors (SynRMs) have attracted much attention because they do not require magnets. Position sensorless control of SynRMs at low speeds is necessary, and several methods have been proposed in this regard. A new position sensorless control method for SynRMs operating in the very low-speed region is proposed. This approach superimposes a high-frequency current with a small and constant amplitude and a constant frequency to the torque current for driving the SynRMs, by using a high-frequency current control system. It has been shown that robust position sensorless control against inductance variations can be realized using this proposed method. In the position sensorless control method based on a superimposing signal, the current should be small. Therefore, in this paper, the capability of the presented approach to achieve a minimum constant amplitude of the high-frequency current is investigated. The experimental results indicate that the proposed method is a feasible one as position sensorless control of SynRMs in very-low speed region even if the superimposed current has a minimum constant amplitude.

DOI： 10.1109/IFEEC47410.2019.9014679

Pole Assignment of Full-Order Flux Observer to Realize Both MTPA Control and Position Sensorless Control of IPMSM Reviewed International journal

Kato S., Hatanaka T., Tomita M., Matsumoto A., Hasegawa M., Doki S.

2019 IEEE 4th International Future Energy Electronics Conference, IFEEC 2019 2019.11

Language：English Publishing type：Research paper (international conference proceedings) Publisher：2019 IEEE 4th International Future Energy Electronics Conference, IFEEC 2019

A flux model that can easily achieve both maximum torque per ampere (MTPA) control and position sensorless control of interior permanent magnet synchronous motors (IPMSMs), is proposed herein. Flux is proposed to be estimated using a full-order observer whose pole assignment is difficult because the order of the error equations of the observer becomes four, and the pole assignment of the full-order observer is proposed. This pole assignment of the full-order observer, in which robust flux estimation against velocity estimation error become possible, is obtained by solving a ?-positive real problem and a H8 control problem. Herein, the experimental result of the position sensorless control of IPMSMs indicates that the proposed pole assignment of the full-order observer is highly useful and can be used to realize MTPA control.

DOI： 10.1109/IFEEC47410.2019.9014918

Comparison of two types of extended electromotive force models in middle / high speed ranges position sensorless control Reviewed International journal

Ohta K., Nimura T., Doki S.

2019 21st European Conference on Power Electronics and Applications, EPE 2019 ECCE Europe 2019.9

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：2019 21st European Conference on Power Electronics and Applications, EPE 2019 ECCE Europe

In this paper, two types of Extended Electromotive Force (EEMF) models are compared and the difference between the position sensorless control performance of these models are also discussed by mathematical equation and experiments.

DOI： 10.23919/EPE.2019.8915112

Detection of contributing object to driving operations based on hidden Markov model Reviewed International journal

Kohjiro Hashimoto, Tetsuyasu Yamada, Takeshi Tsuchiya, Kae Doki, Yuki Funabora, Shinji Doki

International Journal of Advanced Robotic Systems Vol. 16 ( 5 ) page： 172988141987679 - 172988141987679 2019.9

Language：English Publishing type：Research paper (scientific journal) Publisher：SAGE Publications

With increase in the number of elderly people in the Japanese society, traffic accidents caused by elderly driver is considered problematic. The primary factor of the traffic accidents is a reduction in their driving cognitive performance. Therefore, a system that supports the cognitive performance of drivers can greatly contribute in preventing accidents. Recently, the development of devices for visually providing information, such as smart glasses or head up display, is in progress. These devices can provide more effective supporting information for cognitive performance. In this article, we focus on the selection problem of information to be presented for drivers to realize the cognitive support system. It has been reported that the presentation of excessive information to a driver reduces the judgment ability of the driver and makes the information less trustworthy. Thus, indiscriminate presentation of information in the vision of the driver is not an effective cognitive support. Therefore, a mechanism for determining the information to be presented to the driver based on the current driving situation is required. In this study, the object that contributes to execution of avoidance driving operation is regarded as the object that drivers must recognize and present for drivers. This object is called as contributing object. In this article, we propose a method that selects contributing objects among the appeared objects on the current driving scene. The proposed method expresses the relation between the time series change of an appeared object and avoidance operation of the driver by a mathematical model. This model can predict execution timing of avoidance driving operation and estimate contributing object based on the prediction result of driving operation. This model named as contributing model consisted of multi-hidden Markov models. Hidden Markov model is time series probabilistic model with high readability. This is because that model parameters express the probabilistic distribution and its statistics. Therefore, the characteristics of contributing model are that it enables the designer to understand the basis for the output decision. In this article, we evaluated detection accuracy of contributing object based on the proposed method, and readability of contributing model through several experiments. According to the results of these experiments, high detection accuracy of contributing object was confirmed. Moreover, it was confirmed that the basis of detected contributing object judgment can be understood from contributing model.

DOI： 10.1177/1729881419876794

Other Link： http://journals.sagepub.com/doi/full-xml/10.1177/1729881419876794

Position sensorless control of IPMSM in overall speed range by extended EMF Reviewed International journal

Nimura T., Doki S.

2019 21st European Conference on Power Electronics and Applications, EPE 2019 ECCE Europe 2019.9

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：2019 21st European Conference on Power Electronics and Applications, EPE 2019 ECCE Europe

We present the redefined Extended EMF, which is proportional to not only rotor speed but also high frequency injected signal. We propose smooth and simple overall speed range position estimation by only using the redefined Extended EMF without switching control method at all.

DOI： 10.23919/EPE.2019.8915377

Analysis and Evaluation of Current Control System of PMSM with Time-Delay to Improve Parallelization for Implementation on Multi-core Precessors Reviewed International journal

Kim J., Seiya K., Edahiro M., Doki S.

2019 22nd International Conference on Electrical Machines and Systems, ICEMS 2019 2019.8

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：2019 22nd International Conference on Electrical Machines and Systems, ICEMS 2019

With the introduction of multi-core processors, high performance of the control system has become possible. However, the use of multicore is not enough because parallelization is difficult in systems with sequential algorithms, such as motor current control systems. This paper describes the utilization of time-delay to improve parallelism in multi-core implementations of motor control systems. In addition, we propose a method of analyzing and evaluating the effect of time-delay on the control performance according to the insertion location.

DOI： 10.1109/ICEMS.2019.8921506

Sensor Fail-Safe of PMSM Current Control System By Utilizing Current And Position State Estimation Techniques Reviewed International journal

Hori S., Doki S.

2019 22nd International Conference on Electrical Machines and Systems, ICEMS 2019 2019.8

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：2019 22nd International Conference on Electrical Machines and Systems, ICEMS 2019

Along with the expansion of applic tions of PMSM, safety is required for PMSM drive systems. One of the concerns about the safety of the PMSM drive system is sensor failures. In this regard, we aim to make sensor systems redundant and improve fail-safe by using state estimation techniques. In this paper, propose a current control system of PMSM with sensor failsafe by utilizing the techniques and verify some fail-safe performance of the methods in simulation and experiment.

DOI： 10.1109/ICEMS.2019.8921898

自律移動ロボットのロバストな位置推定のための相関係数による多数決センサ選択と統合 Reviewed

大橋臨,舟洞佑記,道木慎二,道木加絵

計測自動制御学会論文集 Vol. 55 ( 7 ) page： 439-446 2019.7

自律移動ロボットのロバストな位置推定のための相関係数による多数決センサ選択と統合 Reviewed

大橋臨, 舟洞佑記, 道木慎二, 道木加絵

計測自動制御学会論文集 Vol. 55 ( 7 ) page： 439-446 2019.7

座標変換器の離散化実装を考慮したPMSMのモデル化と提案モデルに基づく非干渉制御 Reviewed

井上雅理,道木慎二

電気学会論文誌D Vol. 139 ( 7 ) page： 637-644 2019.7

座標変換器の離散化実装を考慮したPMSMのモデル化と提案モデルに基づく非干渉制御 Reviewed

井上雅理, 道木慎二

電気学会論文誌D Vol. 139 ( 7 ) page： 637-644 2019.7

自動車の電動化における最新技術動向

貝塚正明,立花武,小坂卓,道木慎二,太田豊

電気学会論文誌D Vol. 139 ( 6 ) page： 535-542 2019.6

自動車の電動化における最新技術動向 Reviewed

貝塚正明, 立花武, 小坂卓, 道木慎二, 太田豊

電気学会論文誌D Vol. 139 ( 6 ) page： 535-542 2019.6

Quantification of Contributing Degree to Braking Operation of Driver based on the Hidden Markov Model Reviewed International journal

Hashimoto K., Miyosawa T., Yamada T., Tsuchiya T., Doki K., Doki S.

IEEE International Symposium on Industrial Electronics Vol. 2019-June page： 1711 - 1716 2019.6

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE International Symposium on Industrial Electronics

In order to assist cognitive of driver, it is effective for driver to teach the objects that he should recognize in a visual way. However, it is expected that too much information is provided for a driver from the system and it cause him distraction. Therefore, information presentation without exaggeration and without omission is demanded for assistant system. In this paper, it is assumed that the objects which contribute to driver's braking operation should be presented to him. However, these objects changes according to the facing driving situation. Therefore, a selection method of these objects in the appeared objects model is desired. In this paper, a quantification method of contributing degree to braking operation is proposed to select object that system should present. In this method, the degree of contributing to braking operation is calculated based on a driving behavior model. This model express the relationship between the braking operation and time series features of the object that contributes to braking operation. Therefore, in this paper, the modeling method is also proposed.In the experiment, the modeled time series features of the objects that contribute to braking operation was evaluated based on the propose modeling method. Moreover, the calculated degree of contributing to braking operation based on the proposed method was evaluated by using driving simulator. As the results, it was confirmed that high detection accuracy of object that contributes to braking operation was confirmed.

DOI： 10.1109/ISIE.2019.8781518

無人飛行体によるインフラ設備外観自動点検システムのための状態データの精度と作業効率を考慮した計測位置決定 Reviewed

麻晃太朗,舟洞佑記,道木慎二,道木加絵

計測自動制御学会論文集 Vol. 55 ( 5 ) page： 386-392 2019.5

無人飛行体によるインフラ設備外観自動点検システムのための状態データの精度と作業効率を考慮した計測位置決定 Reviewed

麻晃太朗, 舟洞佑記, 道木慎二, 道木加絵

計測自動制御学会論文集 Vol. 55 ( 5 ) page： 386-392 2019.5

A Current Harmonic Minimum PWM for Three-Level Converters Aiming at the Low-Frequency Fluctuation Minimum of Neutral-Point Potential Reviewed International journal Open Access

Guan Bo, Doki Shinji

IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS Vol. 66 ( 5 ) page： 3380 - 3390 2019.5

Design of band elimination filter for PMSM vector control operable in overmodulation region of inverter Reviewed International journal

Nakayama Yosuke, Doki Shinji

ELECTRICAL ENGINEERING IN JAPAN Vol. 207 ( 3 ) page： 45 - 56 2019.5

High-performance V/f control of PMSM using state feedback control based on n-t coordinate system Reviewed International journal

Matsuki Yosuke, Doki Shinji

ELECTRICAL ENGINEERING IN JAPAN Vol. 206 ( 4 ) page： 55 - 65 2019.3

High response torque control of IPMSM using state feedback control based on n-t coordinate system Reviewed International journal

Matsuki Yosuke, Doki Shinji

ELECTRICAL ENGINEERING IN JAPAN Vol. 206 ( 1 ) page： 51 - 62 2019.1

Optimal Two Degrees-of-Freedom Based Neutral Point Potential Control for Three-Level Neutral Point Clamped Converters Reviewed International journal

Guan Bo, Doki Shinji

JOURNAL OF POWER ELECTRONICS Vol. 19 ( 1 ) page： 119 - 133 2019.1

Analysis about control model for position sensorless control of pmsms based on expression of imaginary electromotive force Reviewed International journal

Shota Kondo, Shinji Doki, Atsushi Matsumoto, Mutuwo Tomita

IEEJ Transactions on Industry Applications Vol. 139 ( 1 ) page： 1 - 12 2019

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Institute of Electrical Engineers of Japan

There are many mathematical models for the position sensorless control of permanent magnet synchronous motors (PMSMs), and various position sensorless control methods have already proposed. However, it is necessary to select a control model according to the objective from characteristics of the EMF phase and the robustness against to the motor parameters. An Imaginary Electromotive Force (IEMF) expression can clarify the differences of these models. This paper discusses the characteristics of each model including the Extended Electromotive Force model for position sensorless control that can be applied to the standstill / low speed range from the middle / high speed range. Finally, we show that this IEMF expression is extremely useful in discussing and designing characteristics of the control models of PMSMs.

DOI： 10.1541/ieejias.139.1

Validation of control with contact force distribution for multi-joint wearable robot for body trunk assist Reviewed

Funabora Y., Uchiyama N., Doki S., Doki K.

IEEJ Transactions on Electronics, Information and Systems Vol. 139 ( 11 ) page： 1325 - 1332 2019

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEJ Transactions on Electronics, Information and Systems

In order to make a multi-joint wearable robot for assisting an user's motions on whole body trunk, this paper discusses the usefulness of control with contact force distribution between user and robot for ensuring the safety of the user. To ensure the safety with wearable assistive robots being different structure from the assisting part of the user, sensing and controlling contact force distribution applying to the user is desired. By utilizing the tactile pressure sensors on the robot's surface, the robot can measure physical contact force distribution as pressure distribution. In this paper, a control methodology based on general impedance control system with pressure distribution is presented. Then, the methodology is confirmed possibility to improve safety compared with conventional torque-base control methodology. In some basically simulations, the proposed control system can reduce power of maximum contact force applying to the user, indicating usability of contact force distribution information for improving safety of assist robots with different motions from assisting parts of the user.

DOI： 10.1541/ieejeiss.139.1325

Localization of autonomous mobile robot by integration of multiple sensor information based on sensor information reliability map Reviewed

Doki K., Shinya R., Ohashi N., Funabora Y., Doki S., Torii A., Mototani S.

IEEJ Transactions on Electronics, Information and Systems Vol. 139 ( 12 ) page： 1389 - 1399 2019

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEJ Transactions on Electronics, Information and Systems

We have proposed a localization method of an autonomous mobile robot using multiple sensor information in order to realize robust localization. This method is based on Particle Filter, and bias probability distributions are detected and eliminated before integration of probability distributions for localization. However, the calculation cost is enormous because it is proportional to the number of sensors and particles. In order to reduce the calculation cost for localization, we propose a new localization method using the reliability map of sensor information which is generated based on selection results of sensor information in the previous method in this paper. The usefulness of the proposed method is discussed with some experimental results with a real robot in various real environments.

DOI： 10.1541/ieejeiss.139.1389

Discrete-time PMSM Modeling including Park Transformation and Decoupling Control Based on the Proposed Model Reviewed

Inoue M., Doki S.

IEEJ Transactions on Industry Applications Vol. 139 ( 7 ) page： 637 - 644 2019

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：IEEJ Transactions on Industry Applications

This paper describes a new discrete-time PMSM model for the discrete design of current vector control systems. The discrete design of current control system minimizes the discretization error and improves the current control performance at the sampling point. The conventional PMSM model discretization method presumes that park transformation runs continuously. When the sampling frequency is considerably lower than the fundamental electric frequency, this assumption is invalid and the control performance will degrade due to modeling error. In this paper, the authors propose a method of PMSM model discretization considering discrete-time park transformation and design an additional cross-coupling compensator for the proposed model. The experimetntation results demonstrate the effectiveness of the proposed model.

DOI： 10.1541/ieejias.139.637

Markerless Measurement System of Body Surface Deformation for Structure Determination of Wearable Robot Reviewed

Honda Shota, Funabora Yuki, Doki Shinji, Doki Kae

2019 IEEE/SICE INTERNATIONAL SYMPOSIUM ON SYSTEM INTEGRATION (SII) page： 135-140 2019

Control System Based on Contact Force Distribution for Wearable Robot with Tactile Sensor Reviewed

Ito Daiki, Funabora Yuki, Doki Shinji, Doki Kae

2019 IEEE/SICE INTERNATIONAL SYMPOSIUM ON SYSTEM INTEGRATION (SII) page： 259-263 2019

Detection of contributing object to driving operations based on hidden Markov model Reviewed

Kohjiro Hashimoto, Tetsuyasu Yamada, Takeshi Tsuchiya, Kae Doki, Yuki Funabora, Shinji Doki

International Journal of Advanced Robotic Systems page： 1-15 2019

Quantification of Contributing Degree to Braking Operation of Driver based on the Hidden Markov Model Reviewed

Hashimoto Kohjiro, Miyosawa Tadashi, Yamada Tetsuyasu, Tsuchiya Takeshi, Doki Kae, Doki Shinji

2019 IEEE 28TH INTERNATIONAL SYMPOSIUM ON INDUSTRIAL ELECTRONICS (ISIE) page： 1711-1716 2019

Efficiency Improvement of Motor Drive System by using a GaN Three Phase Inverter Reviewed

Nakayama Yosuke, Kanazawa Yasuki, Kondo Fumiya, Inoue Masamichi, Ohta Kazuki, Doki Shinji, Shiozaki Koji

2019 IEEE INTERNATIONAL CONFERENCE ON INDUSTRIAL TECHNOLOGY (ICIT) page： 1599-1604 2019

Position Sensorless Control of IPMSM in Overall Speed Range by Extended EMF Reviewed

Nimura Takumi, Doki Shinji

2019 21ST EUROPEAN CONFERENCE ON POWER ELECTRONICS AND APPLICATIONS (EPE '19 ECCE EUROPE) page： . 2019

Comparison of Two Types of Extended Electromotive Force Models in Middle / High Speed Ranges Position Sensorless Control Reviewed

Ohta Kazuki, Nimura Takumi, Doki Shinji

2019 21ST EUROPEAN CONFERENCE ON POWER ELECTRONICS AND APPLICATIONS (EPE '19 ECCE EUROPE) page： . 2019

An efficient evaluation of signal injection method for position sensorless control of IPMSMs based on an extended EMF model at low-speed range Reviewed International journal

Saito R., Yamamoto T., Doki S., Ohnuma T.

IEEJ Transactions on Industry Applications Vol. 139 ( 9 ) page： 824 - 831 2019

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEJ Transactions on Industry Applications

This paper presents signal conditions taking motor efficiency into account for position sensorless control of interior permanent magnet synchronous motors (IPMSMs). Signal injection is necessary for position estimation based on an extended electromotive force (EEMF) model at standstill and low speeds. We have proposed a maximum torque control reference frame and the EEMF model suitable for signal injection, and we executed sensorless control in the entire driving area. However, its effects on motor efficiency have not been evaluated in the previous study. Therefore, in this paper, we optimize the amplitude, phase, and frequency of signal current. Moreover, we applied a signal current amplitude adjusting method. This method makes the signal current amplitude minimum based on the EEMF. As a result, we can maintain constant efficiency including copper loss and other losses of the motor, regardless of the signal frequency. The signal frequency can be freely selected in terms of the motor efficiency, so that the proposed method can improve the flexibility to design the injection signals for the position sensorless control of the IPMSMs.

DOI： 10.1541/ieejias.139.824

Latest technological trends for electrification of automobile technologies Reviewed International journal

Kaizuka M., Tachibana T., Kosaka T., Doki S., Ota Y.

IEEJ Transactions on Industry Applications Vol. 139 ( 6 ) page： 535 - 542 2019

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEJ Transactions on Industry Applications

Global warming and the risk of depletion of fossil fuels are global concerns. The demand for environmental performance of automobiles is becoming severer year by year. In this regard, automotive manufacturers have designed BEVs, PHVs, HEVs and FCVs to meet CO2 regulation. This report presents the recent technological trends related to the main components of electrical vehicles.

DOI： 10.1541/ieejias.139.535

Comparison of Two Types of Extended Electromotive Force Models in Middle / High Speed Ranges Position Sensorless Control Reviewed International journal

Ohta Kazuki, Nimura Takumi, Doki Shinji

2019 21ST EUROPEAN CONFERENCE ON POWER ELECTRONICS AND APPLICATIONS (EPE '19 ECCE EUROPE) page： . 2019

Control System Based on Contact Force Distribution for Wearable Robot with Tactile Sensor Reviewed International journal

Ito Daiki, Funabora Yuki, Doki Shinji, Doki Kae

2019 IEEE/SICE INTERNATIONAL SYMPOSIUM ON SYSTEM INTEGRATION (SII) page： 259-263 2019

Efficiency Improvement of Motor Drive System by using a GaN Three Phase Inverter Reviewed International journal

Nakayama Yosuke, Kanazawa Yasuki, Kondo Fumiya, Inoue Masamichi, Ohta Kazuki, Doki Shinji, Shiozaki Koji

2019 IEEE INTERNATIONAL CONFERENCE ON INDUSTRIAL TECHNOLOGY (ICIT) page： 1599-1604 2019

Quantification of Contributing Degree to Braking Operation of Driver based on the Hidden Markov Model Reviewed International coauthorship International journal

Hashimoto Kohjiro, Miyosawa Tadashi, Yamada Tetsuyasu, Tsuchiya Takeshi, Doki Kae, Doki Shinji

2019 IEEE 28TH INTERNATIONAL SYMPOSIUM ON INDUSTRIAL ELECTRONICS (ISIE) page： 1711-1716 2019

Position Sensorless Control of IPMSM in Overall Speed Range by Extended EMF Reviewed International coauthorship International journal

Nimura Takumi, Doki Shinji

2019 21ST EUROPEAN CONFERENCE ON POWER ELECTRONICS AND APPLICATIONS (EPE '19 ECCE EUROPE) page： . 2019

Markerless Measurement System of Body Surface Deformation for Structure Determination of Wearable Robot Reviewed International journal

Honda Shota, Funabora Yuki, Doki Shinji, Doki Kae

2019 IEEE/SICE INTERNATIONAL SYMPOSIUM ON SYSTEM INTEGRATION (SII) page： 135-140 2019

Analysis of an application of the extended electromotive force model based position sensorless control on the wound-field synchronous motor with dual-three phases in standstill/low speed region Reviewed International journal

Wang S., Imai K., Doki S.

Proceedings: IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society page： 5789 - 5794 2018.12

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：Proceedings: IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society

Sensorless control has become a popular research area for ac drives. However, most of the works are attributed to conventional three-phase drives. Given that applications of multiphase machines keep spreading, studies of position sensorless for them are necessary. For the object in this paper, some studies for sensorless control in middle/high speed region are reported. To accomplish a full-speed range sensorless control, a study about the standstill/low speed sensorless control of the target motor is proposed in this paper. Particularly, conventional signal injection methods utilized in three-phase ac drives meet a new issue caused by the inner magnetic couplings of the system when applying to the object in this paper. It may lead to failure of sensorless control and torque ripple enlargement. Therefore, analyses to solve the issue become the main interest of this paper, simulation results are demonstrated in the last section.

DOI： 10.1109/IECON.2018.8591145

Evaluation in real world of the measuring position determination for visual inspection using UAV Reviewed

Asa K., Funabora Y., Doki S., Doki K.

Proceedings: IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society page： 2711 - 2716 2018.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings: IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society

This paper evaluates our measuring position determination method of Unmanned Aerial Vehicles (UAVs) for automatic visual inspection through an experimentation in real world. This method is under the assumption that the 3D model of a target facility, required accuracy of gathering data and specs of instruments are given. The triangular polygons for shape description of the 3D model are reconstructed for measurement and the measuring positions: the waypoints that an UAV travels to gather the accurate data of the target facility efficiently are calculated systematically. For basic evaluation of this method, we conducted an experimentation in real world. The measuring positions were calculated for an actual target and a camera. An experimenter brought a camera to the measuring positions and gathered image data. This experimentation result showed the effectivity of the method.

DOI： 10.1109/IECON.2018.8591270

Flight path planning of multiple UAVs for robust localization near infrastructure facilities Reviewed International journal

Maeda K., Doki S., Funabora Y., Doki K.

Proceedings: IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society page： 2522 - 2527 2018.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings: IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society

To realize automatic inspections for infrastructure facilities by an Unmanned Aerial Vehicle (UAV), improvement of localization performance is needed. Especially, automatic flight does not work in environments near facilities such as under the bridge because GNSS signals does not reach the UAV. We research a localization system using subsidiary UAVs that assist localization of an inspection UAV (main UAV). In this system, the positioning of the subsidiary UAVs is important to correctly complement the position information of the main UAV. In this paper, as the first stage of research, we consider a path of a single subsidiary UAV using preliminary information: the 3D geometrical data of a target facility, the inspection path of the main UAV, and the arrangement of GNSS satellites during the inspection. A simple simulation shows that the localization of the main UAV does not collapse through the whole path under the evaluation of the GNSS positioning precision of each UAV.

DOI： 10.1109/IECON.2018.8592710

Prototype of Wearable Robot with Tactile Sensor Measurable Contact Force Distribution with User Reviewed International journal

Ito D., Funabora Y., Doki S., Doki K.

2018 15th International Conference on Control, Automation, Robotics and Vision, ICARCV 2018 page： 960 - 965 2018.12

Language：English Publishing type：Research paper (international conference proceedings) Publisher：2018 15th International Conference on Control, Automation, Robotics and Vision, ICARCV 2018

To improve safety of wearable assist robots, the authors make a prototype wearable robot suitable for the contact force distribution feedback control system. Because wearable assist robots contact the user and apply force directly, ensuring safety of the user is most important. In order to improve safety from the aspect of control, a contact force distribution feedback control system has been researched. The system controls contact force between the user and a robot directly. Although the system validated in principal with a simple robot model on simulation, validation with an actual robot has not done yet. There are no wearable robots measurable the contact force distribution with user. In order to measure the contact force distribution for the control system, two points: Measurement reproducibility and measurement as distribution, are necessary. In this paper, a prototype robot that satisfies the two points is made. The robot is confirmed to have the two points necessary for the system by measurement experiment.

DOI： 10.1109/ICARCV.2018.8581233

Initial Position Error Convergence of Position Sensorless Control of PMSM by using Extended Electromotive Force Excited by Signal Injection Reviewed International journal

Nimura T., Kondo S., Doki S., Tomita M.

2018 20th European Conference on Power Electronics and Applications, EPE 2018 ECCE Europe 2018.10

Language：English Publishing type：Research paper (international conference proceedings) Publisher：2018 20th European Conference on Power Electronics and Applications, EPE 2018 ECCE Europe

This paper discusses the initial position error convergence of position sensorless control of Permanent Magnet Synchronous Motor by using Extended Electromotive Force excited by signal injection when motor parameter error exists, and verify that by experimental results.

Position Sensorless Control based on Pattern Matching Method using Multiple Template Data Sets to Improve Position Control Error Reviewed International journal

Song H., Doki S.

2018 20th European Conference on Power Electronics and Applications, EPE 2018 ECCE Europe 2018.10

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：2018 20th European Conference on Power Electronics and Applications, EPE 2018 ECCE Europe

This paper presents a position sensorless control scheme based on pattern matching method for high power density Interior Permanent Magnet Synchronous Motors (IPMSMs) that have non-sinusoidal inductance spatial distribution. The pattern matching method achieves the closed loop position sensorless control under heavy load condition. However, atypical position control control errors are generated. To improve the position control errors, a new pattern matching method is proposed in this paper. The proposed method estimates the rotor position by using multiple template data sets which created while changing a current phase. Through experimental results, the effectiveness of the proposed method is presented.

Improvement in control performance of PMSMs by deactivation of antiwindup control in the overmodulation range of an inverter Reviewed International journal

Nakayama Y., Doki S.

2018 20th European Conference on Power Electronics and Applications, EPE 2018 ECCE Europe 2018.10

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：2018 20th European Conference on Power Electronics and Applications, EPE 2018 ECCE Europe

This paper proposes a current control system which deactivates an antiwindup control for improving the control performance of PMSMs in the overmodulation region of an inverter. Control performance of PMSMs cannot be improved appropriately without countermeasure against harmonic components which are generated in this region. Deactivating of antiwindup control can be a countermeasure against these harmonic components, however deterioration of current responses due to windup phenomenon is unavoidable. Proposed control system reduces the deterioration of torque response due to windup phenomenon by deactivating the antiwindup control only in the steady state in the overmodulation region. Proposed control system have confirmed that it can achieve fast torque response and high power operation by simple algorithm without motor parameters.

Investigating Pole Assignment of Full-Order Observer Based on Extended Electromotive Force for Position Sensorless Control of IPMSMs Reviewed International journal

Toshiya Mabuchi, Takato Hatanaka, Mutuwo Tomita, Masaru Hasegawa, Shinji Doki, Shinji Kato

Proceedings - 2018 23rd International Conference on Electrical Machines, ICEM 2018 page： 1579 - 1585 2018.10

Language：English Publishing type：Research paper (international conference proceedings) Publisher：Institute of Electrical and Electronics Engineers Inc.

Several position sensorless control methods of interior permanent magnet synchronous motors (IPMSMs) using observers have been proposed. In the case of full-order observers, these designs are difficult because the order of the error equations of observers becomes an order of four. In this paper, to realize the position sensorless control of IPMSMs, a design method for full-order observers based on the extended electromotive force (EEMF) is proposed, and the pole assignment of the proposed observer is studied. Experimental results of the position sensorless control of an IPMSM show the usefulness of this proposed design method for the full-order observer compared to the case where poles are merely assigned on the left half plane.

DOI： 10.1109/ICELMACH.2018.8506894

Maximum Torque Control Reference Frame Based on a Torque Map for IPMSMs with Large Inductance Variation Reviewed International journal

Ohta K., Ohnuma T., Doki S.

2018 International Power Electronics Conference, IPEC-Niigata - ECCE Asia 2018 page： 1223 - 1227 2018.10

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：2018 International Power Electronics Conference, IPEC-Niigata - ECCE Asia 2018

In this paper, we summarize a method of applying a maximum torque control reference frame to IPMSMs with large influence of magnetic saturation. Conventionally, a formula based on the torque equation with motor parameters of IPMSMs has been used to calculate the phase angle of the maximum torque control reference frame. However, the equation is greatly affected by inductance variation due to magnetic saturation. Therefore, we propose the phase angle determination method based on a torque map. The method is not affected by inductance variation because it does not need motor parameters directly. Performance improvement is confirmed by simulation and actual machine experiments.

DOI： 10.23919/IPEC.2018.8507807

The Multiple Degree of Freedom based Neutral Point Potential Control of Three Level Neutral Point Clamped Converters Reviewed International journal

Guan B., Doki S.

2018 International Power Electronics Conference, IPEC-Niigata - ECCE Asia 2018 page： 1032 - 1037 2018.10

Language：English Publishing type：Research paper (international conference proceedings) Publisher：2018 International Power Electronics Conference, IPEC-Niigata - ECCE Asia 2018

Although the virtual space PWM and the dual wave modulation (DWM) method can eliminate the low frequency neutral point potential (NPP) fluctuation, which appears in some NPP control based on the nearest three vector PWM essentially, they will increase the switching frequency and fade the control ability of the NPP drift problem. In this paper, a novel multiple degree of freedom based NPP control with the strong control ability of low frequency NPP fluctuation and NPP drift problem is proposed for three level converter. The traditional DWM method sacrifices many control domains of neutral point current (io) to keep io zero, by setting the zero sequence voltage to an appropriate value. On the contrary, the proposed method introduces three degree of freedom to control the NPP, which makes it have the largest NPP control domains. The comparison on the control domains of io for DMW method and proposed method is discussed at first. Then, some simulation are also carried out to verify the correctness and effectiveness of proposed method.

DOI： 10.23919/IPEC.2018.8507804

High Stability V/f Control of PMSM Using State Feedback Control Based on n-t Coordinate System Reviewed International journal

Matsuki Y., Doki S.

2018 International Power Electronics Conference, IPEC-Niigata - ECCE Asia 2018 page： 2224 - 2228 2018.10

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：2018 International Power Electronics Conference, IPEC-Niigata - ECCE Asia 2018

This paper proposes a new V/f control method for permanent magnetic synchronous motors (PMSM) without position sensor. The proposed method uses state feedback control based on a n-t coordinate system. The t-axis is a tangent line of a constant voltage ellipse, and the n-axis is a normal line of the ellipse. The t-axis current is utilized to keep the system poles in the stable plane in low speed of motor and to achieve high stability.

DOI： 10.23919/IPEC.2018.8507624

New Search Algorithm of Model Predictive Control to Reducing Calculation Amount for Improving Steady Current Control Performance Reviewed International journal

Shimaoka M., Doki S.

2018 International Power Electronics Conference, IPEC-Niigata - ECCE Asia 2018 page： 1747 - 1751 2018.10

Language：English Publishing type：Research paper (international conference proceedings) Publisher：2018 International Power Electronics Conference, IPEC-Niigata - ECCE Asia 2018

We have proposed Model predictive Control which can manage the voltage phase resolution. This method decides the optimum permutation of voltage vector by predicting current behaviors for all permutations and evaluating behaviors. Our method can realize same steady current control performance of FOC, however, there is the issue which calculation amount become very huge. In this paper, we propose new search algorithm of our MPC which can reduce calculation amount. In Propose algorithm, we take a notice that control set of our MPC can be classified by type and number of the voltage vector. Calculation amount is reduced by selecting search space depending on operation points. We show that new algorithm can be greatly reduced calculation amount while keeping steady current control performance.

DOI： 10.23919/IPEC.2018.8507886

PMSM Model Discretization in Consideration of Park Transformation for Current Control System Reviewed International journal

Inoue M., Doki S.

2018 International Power Electronics Conference, IPEC-Niigata - ECCE Asia 2018 page： 1228 - 1233 2018.10

Language：English Publishing type：Research paper (international conference proceedings) Publisher：2018 International Power Electronics Conference, IPEC-Niigata - ECCE Asia 2018

This paper describes a new discrete-time PMSM model for discrete design of current vector control system. Discrete design of current control system is a via discrete-time PMSM model. This controller minimizes dis-cretization error and ensure perfect control performance at sampling point. Conventional discretization method presume park transformation runs continuously. When sampling frequency is too lower than fundamental electric frequency, this assumption is invalid and control performance will degrade by modeling error. In this paper, authors propose the method of PMSM model discretization in consideration of discrete-time park transformation. Simulation results show the effectiveness of proposed model.

DOI： 10.23919/IPEC.2018.8507948

Majority rule sensor fusion system with particle filter for robust robot localization Reviewed International journal

Ohashi N., Funabora Y., Doki S., Doki K.

IEEE/ASME International Conference on Advanced Intelligent Mechatronics, AIM Vol. 2018-July page： 1106 - 1111 2018.8

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE/ASME International Conference on Advanced Intelligent Mechatronics, AIM

This paper discusses a robust localization method that uses particle filtering. A particle filter can suppress the influence of temporary noise on a sensor based on past sensor data. However, localization fails when a sensor is affected by noise that lasts for several minutes even when using a particle filter. We have previously proposed a majority rule-based sensor fusion system that removes sensors affected by such constant noise. To date, we have conducted some experiments to evaluate the effectiveness of this system without particle filter. In this paper, we experimentally confirm the effectiveness of this system with particle filtering. The results show that the proposed system reduces position errors in part of the environment.

DOI： 10.1109/AIM.2018.8452415

Study on an Evaluation Method of Coincident Timing Skill of Driver Based on Driving Behavior Model of Brake Operation Reviewed International journal

Hashimoto K., Doki K., Doki S.

IEEE International Symposium on Industrial Electronics Vol. 2018-June page： 782 - 787 2018.8

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE International Symposium on Industrial Electronics

Traffic accidents caused by elderly drivers have become an important social issue in Japan. The primary factor of traffic accidents by elderly drivers is a reduction in their driving skill. In this case, in order to assist operation of driver whose driving skill is reduced, the system must be able to evaluate his driving behavior skill. In this paper, we propose a evaluation method of driver's driving skill. Here, coincident timing skill is focused on. A driver decides an execution timing of his operation based on prediction of time series change of situation around him. When execution timing of operation of the driver has the widely variability in spite of the same driving scene, it is considered that he have a reduced ability to drive vehicle. This magnitude of variability of execution timing of operation of driver is defined as coincident timing skill of the driver. In this paper, in order to evaluate this coincident timing skill, a driving behavior modeling technique is applied. Driving behavior model is used to predict driver's operation. And we have proposed a driving behavior modeling method to predict driver's operation. In our method, the execution timing of driver's operation is modeled by probability model. Therefore, our model has the potential to evaluate the driver's coincident timing skill by analyzing this probability model. According to the above viewpoint, we propose a evaluation method of coincident timing skill based on our driving behavior model. In the experiment, the driving behavior models of brake operation with difference execution timing are generated. Then, the results that the difference of each coincident timing skills is evaluated quantitatively based on the proposed method are shown.

DOI： 10.1109/ISIE.2018.8433732

The Voltage Phase Control Strategy for Six-Step Operation in SPMSM Drives Considering the 6/12-Order Torque Ripple Reviewed International journal

Guan B., Doki S.

ITEC Asia-Pacific 2018 - 2018 IEEE Transportation Electrification Conference and Expo, Asia-Pacific: E-Mobility: A Journey from Now and Beyond 2018.8

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：ITEC Asia-Pacific 2018 - 2018 IEEE Transportation Electrification Conference and Expo, Asia-Pacific: E-Mobility: A Journey from Now and Beyond

In order to reduce switching frequency and achieve maximum utilization rate of DC-link voltage, traditional voltage phase controller realizes six-step operation via an integrator in SPMSM drives. However, it is not able to achieve a good torque performance in steady state and transient state at the same time, due to the integral saturation problem and bandwidth limit of the integrator. By analyzing the effects of the 6/12-order torque ripple, this paper claims that the 6/12-order torque ripple derived from six-step operation directly limits the bandwidth of control system. Thus, a model-based voltage phase controller is proposed in this paper to replace the integrator. The proposed method can obtain a faster torque response in transient state as well as a good torque performance in steady state. Finally, some simulation results are also given to verify the correctness and feasibility of proposed method.

DOI： 10.1109/ITEC-AP.2018.8432597

A neutral point potential control for three-level neutral-point-clamped converters based on the search optimization method of the two degrees of freedom Reviewed International journal

Bo Guan, Shinji Doki

IEEJ Transactions on Electrical and Electronic Engineering Vol. 13 ( 8 ) page： 1196 - 1207 2018.8

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：John Wiley and Sons Inc.

To realize the neutral point potential (NPP) control for three-level neutral-point-clamped (TL-NPC) converters, a novel NPP control based on the search optimization method of the two degrees of freedom is proposed in this paper. It can overcome the low-frequency NPP fluctuation problem that appears under nearest-three-vector pulse width modulation (PWM)-based NPP control under some operating conditions. Although the traditional dual modulation wave method can also solve the low-frequency NPP problem, the zero-sequence voltage is limited under this modulation. It decreases the control domain of the neutral point current (io), which causes serious NPP drift problem especially in some special operating conditions, such as a long dead time, a strong asymmetrical load, or serious switch device inconsistency. The proposed method can expand the control domain of io by defining a new degree of freedom, thus lifting the limits of the zero-sequence voltage and searching for the optimal two degrees of freedom. The wider control domain of io corresponds to a stronger NPP control ability. Experiments are carried out finally to prove the merits of the proposed method, by comparing the switching frequency, the NPP control speed, and the output performance. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley &amp
Sons, Inc.

DOI： 10.1002/tee.22683

A robust neutral point potential control for single phase three level rectifier based on the multiple degree of freedom Reviewed

Guan B.

Proceedings of the IEEE International Conference on Industrial Technology Vol. 2018-February page： 606 - 611 2018.4

Filter setting for improving the current control performance of IPMSMs in overmodulation region of inverter Reviewed

Yosuke Nakayama, Shinji Doki, Atsushi Matsumoto, Masaru Hasegawa

Proceedings of the International Conference on Power Electronics and Drive Systems Vol. 2017- page： 703 - 708 2018.2

Language：English Publishing type：Research paper (international conference proceedings) Publisher：Institute of Electrical and Electronics Engineers Inc.

This paper presents the filter setting for improving the current control performance of IPMSMs in overmodulation region of inverter. To operate IPMSMs in the overmodulation region, it is necessary to deal with harmonic components. Generally, harmonics suppression method based on harmonics current model is utilized to deal with these components, however, it requires accurate motor parameters. In this paper, Band Stop Filter is utilized to suppress the harmonic components, and weight averaging method is applied to improve the current responses, without any motor parameter. Simulation results are demonstrated to show the current control performance and the operation range of proposed method.

DOI： 10.1109/PEDS.2017.8289245

Mathmatical models on extended electromotive force exited by high frequency signal injection and its robustness for position estimation of PMSM Reviewed International journal

Shota Kondo, Shinji Doki, Mutuwo Tomita

Proceedings of the International Conference on Power Electronics and Drive Systems Vol. 2017- page： 172 - 177 2018.2

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：Institute of Electrical and Electronics Engineers Inc.

The Extended Electromotive Force(EEMF) has a high potential because that the model enables position estimation by utilizing not only electromotive force but also saliency of inductance. In particular, the EEMF consists of two components, excited by rotor speed and high-frequency signal injection. The characteristic of EEMF excited by speed has been proposed sufficiently. This paper describes analysis of robustness of parameter error in two types of Extended Electromotive Force (EEMF) exited by high frequency signal injection for position sensorless control. Finally, formula evaluation indicates that each EEMF model has different robustness of parameter error.

DOI： 10.1109/PEDS.2017.8289235

Contact force distribution predictive control system for wearable robot with tactile sensors Reviewed International journal

Sato A., Funabora Y., Doki S., Doki K.

2017 Asian Control Conference, ASCC 2017 Vol. 2018-January page： 1373 - 1378 2018.2

Language：English Publishing type：Research paper (international conference proceedings) Publisher：2017 Asian Control Conference, ASCC 2017

The authors aim for safe assistance by feedback control of the contact force in the wearable robot. Securing safety for users is of utmost importance for wearable robots. For safe assistance of complex body parts such as the torso, the robot is desirable to be able to sense the contact force: the force applied to the human body by the robot. The authors have been studying robots sensing contact force distribution from tactile sensors on the robot surface as pressure distribution. The robot is controlled to reduce superfluous contact force. In this paper, a new control method, contact force distribution predictive control system, is proposed. This method predicts the contact force distribution of the next step from the current link positions and contact force distribution of the robot. The robot is controlled so as to realize the optimum contact force distribution. The proposed method is compared with the conventional control based on joint torque and the effectiveness of our method is verified.

DOI： 10.1109/ASCC.2017.8287372

Study on the Model Structure of Human Machine Operation to Evaluate a Coincident Timing Skill Reviewed

Kohjiro Hashimoto, Kae Doki, Shinji Doki

Electronics and Communications in Japan Vol. 101 ( 2 ) page： 74 - 86 2018.2

Language：English Publishing type：Research paper (scientific journal) Publisher：Wiley-Liss Inc.

With an increase in the elderly population, traffic accidents caused by elderly drivers have become an important social issue in Japan. The primary factor of traffic accidents by elderly drivers is a reduction in their driving skill. Therefore, elderly drivers are required by law to conduct regularly a driving aptitude test in Japan. If the driving skill of the driver is inadequacy, he is subject to punishment, such as driver license revoked. However, there is not appropriate evaluation index of driving skill. We have proposed a modeling method of driving behavior to support one. Proposed driving behavior model is generated based on the actual driving data of driver, and the generated model has some kind of habit and pattern of the driver. Therefore, it is considered that it is possible to evaluate driving skill of a driver by analyzing the generated model. According this reason, we aim to propose a modeling method of driving behavior to evaluate driving skill. Here, a coincident timing skill of driver is focused as a driving skill. In the case of driving behavior, the execution timing of driving operations is decided based on the prediction of subsequent change of the outside environment information. The accuracy of this decided execution timing of operation depend on the above prediction is called as the coincident timing skill. In the proposed model, the causality between the situation around a person and operation of driver is modeled by Hidden Markov Model, and timing probability distribution is added to Hidden Markov Model in order to evaluate this coincident timing skill. The timing probability distribution expresses the execution timing of next operation of driver. Therefore, it is possible to detect the information of the coincident timing skill of driver from the timing probability distribution. In the experiment, the controller operation of a radio controlled vehicle is modeled by the proposed method, and the usefulness of the proposed model is examined through some experimental results.

DOI： 10.1002/ecj.12049

Position sensorless control for wound-field synchoronous motor with double three-phase wound stator using new EEMF model Reviewed International journal

Imai K., Doki S., Fujii K., Jung S.

31st International Electric Vehicle Symposium and Exhibition, EVS 2018 and International Electric Vehicle Technology Conference 2018, EVTeC 2018 2018

Language：English Publishing type：Research paper (international conference proceedings) Publisher：31st International Electric Vehicle Symposium and Exhibition, EVS 2018 and International Electric Vehicle Technology Conference 2018, EVTeC 2018

In this paper, a position sensorless control method for the Wound-field Synchronous Motor with Double Threephase wound stator(D-WFSM) in middle or high speed driving is proposed. Extended electromotive force observer used commonly for PMSMs is selected for the target motor’s position sensorless control method. However, due to the voltage phase control method, the estimated position error contains high frequency components. It would deteriorate the position estimation. Therefore, in this paper, a new extended electromotive force model for two-set motors is proposed. Then, the effectiveness of the proposed method is verified through simulation.

Improvement of position control error for position sensorless control based on pattern matching method Reviewed

Song H., Doki S.

IEEJ Transactions on Industry Applications Vol. 138 ( 12 ) page： 902 - 910 2018

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：IEEJ Transactions on Industry Applications

Sensorless control based on a pattern matching method is proposed for interior permanent magnet synchronous motors (IPMSMs), which have non-sinusoidal inductance spatial distribution at a standstill and very low speed regions. By using the pattern matching method, closed-loop-position sensorless control is possible for IPMSMs even under the heavy load condition, but atypical position error occurs. A previous study examined why position control errors are generated in the pattern matching method. This paper presents three improvement methods for the position control error by considering the cause of the position control error. In addition, characteristics of each proposed method are clearly explained, and their effectiveness is presented by simulation and experimental results.

DOI： 10.1541/ieejias.138.902

High response torque control of IPMSM using state feedback control based on n-t coodinate system Reviewed International journal

Matsuki Y., Doki S.

IEEJ Transactions on Industry Applications Vol. 138 ( 7 ) page： 563 - 573 2018

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEJ Transactions on Industry Applications

This paper proposes a torque control method for interior permanent magnet synchronous motors (IPMSMs). The proposed method uses state feedback control based on a new n-t coordinate system and controls the voltage amplitude and phase based on the coordinate system. The t-axis is a tangent line of the constant voltage ellipse, and the n-axis is a normal line of the ellipse. The n-axis current is utilized to place the poles of the transfer function at the desired position and reduce the mutual coupling between the voltage amplitude controller and phase controller. The proposed method realizes a high torque response even under parameter variation for the linear range and over-modulation range of the inverter, including a six-step mode. The effectiveness of the proposed method was verified by simulation and experimental results.

DOI： 10.1541/ieejias.138.563

Evaluation method to estimate position control error in position sensorless control based on pattern matching method Reviewed International journal

Hamin Song, Shinji Doki

IEEJ Journal of Industry Applications Vol. 7 ( 1 ) page： 73 - 79 2018

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：Institute of Electrical Engineers of Japan

A sensorless control based on a pattern matching method is proposed for interior permanent magnet synchronous motors which have non-sinusoidal inductance spatial distribution, at a standstill and in very-low-speed regions. A previous study indicated that closed-loop-position sensorless control can be achieved under heavy load conditions. However, position control errors are generated at atypical rotor positions, and the reason for this has not been clarified. Moreover, there remains an issue in which this position error cannot be perceived before position sensorless control is carried out. This study examines why position control errors are generated in the pattern matching method. Furthermore, an evaluation method that estimates position control error in advance is proposed using the clarified mechanism of position error generation. The effectiveness of the proposed method is demonstrated by comparing experimental and evaluation results.

DOI： 10.1541/ieejjia.7.73

Majority Rule Sensor Fusion System with Particle Filter for Robust Robot Localization Reviewed

Ohashi Nozomu, Funabora Yuki, Doki Shinji, Doki Kae

2018 IEEE/ASME INTERNATIONAL CONFERENCE ON ADVANCED INTELLIGENT MECHATRONICS (AIM) page： 1106-1111 2018

High Stability V/f Control of PMSM Using State Feedback Control Based on n-t Coordinate System Reviewed

Matsuki Yosuke, Doki Shinji

2018 INTERNATIONAL POWER ELECTRONICS CONFERENCE (IPEC-NIIGATA 2018 -ECCE ASIA) page： 2224-2228 2018

EEMFs Excited by Signal Injection for Position Sensorless Control of PMSMs and Their Performance Comparison by Using Imaginary Electromotive Force Reviewed

Nimura Takumi, Kondo Shota, Doki Shinji, Tomita Mutuwo

2018 INTERNATIONAL POWER ELECTRONICS CONFERENCE (IPEC-NIIGATA 2018 -ECCE ASIA) page： 1295-1300 2018

Improvement in Control Performance of PMSMs by Deactivation of Antiwindup Control in the Overmodulation Range of an Inverter Reviewed

Nakayama Yosuke, Doki Shinji

2018 20TH EUROPEAN CONFERENCE ON POWER ELECTRONICS AND APPLICATIONS (EPE'18 ECCE EUROPE) page： . 2018

The Multiple Degree of Freedom based Neutral Point Potential Control of Three Level Neutral Point Clamped Converters Reviewed

Guan Bo, Doki Shinji

2018 INTERNATIONAL POWER ELECTRONICS CONFERENCE (IPEC-NIIGATA 2018 -ECCE ASIA) page： 1032-1037 2018

Prototype of Wearable Robot with Tactile Sensor Measurable Contact Force Distribution with User Reviewed

Ito Daiki, Funabora Yuki, Doki Shinji, Doki Kae

2018 15TH INTERNATIONAL CONFERENCE ON CONTROL, AUTOMATION, ROBOTICS AND VISION (ICARCV) page： 960-965 2018

Position Sensorless Control based on Pattern Matching Method using Multiple Template Data Sets to Improve Position Control Error Reviewed

Song Hamin, Doki Shinji

2018 20TH EUROPEAN CONFERENCE ON POWER ELECTRONICS AND APPLICATIONS (EPE'18 ECCE EUROPE) page： . 2018

PMSM Model Discretization in Consideration of Park Transformation for Current Control System Reviewed

Inoue Masamichi, Doki Shinji

2018 INTERNATIONAL POWER ELECTRONICS CONFERENCE (IPEC-NIIGATA 2018 -ECCE ASIA) page： 1228-1233 2018

New Search Algorithm of Model Predictive Control to Reducing Calculation Amount for Improving Steady Current Control Performance Reviewed

Shimaoka Masahiro, Doki Shinji

2018 INTERNATIONAL POWER ELECTRONICS CONFERENCE (IPEC-NIIGATA 2018 -ECCE ASIA) page： 1747-1751 2018

Maximum Torque Control Reference Frame Based on a Torque Map for IPMSMs with Large Inductance Variation Reviewed

Ohta Kazuki, Ohnuma Takumi, Doki Shinji

2018 INTERNATIONAL POWER ELECTRONICS CONFERENCE (IPEC-NIIGATA 2018 -ECCE ASIA) page： 1223-1227 2018

Initial Position Error Convergence of Position Sensorless Control of PMSM by using Extended Electromotive Force Excited by Signal Injection Reviewed

Nimura Takumi, Kondo Shota, Doki Shinji, Tomita Mutuwo

2018 20TH EUROPEAN CONFERENCE ON POWER ELECTRONICS AND APPLICATIONS (EPE'18 ECCE EUROPE) page： . 2018

A Robust Neutral Point Potential Control for Single Phase Three Level Rectifier based on The Multiple Degree of Freedom Reviewed

Guan Bo, Doki Shinji

2018 IEEE INTERNATIONAL CONFERENCE ON INDUSTRIAL TECHNOLOGY (ICIT) page： 606-611 2018

Position Sensorless Control for Wound-Field Synchronous Motor with Double Three-phase Wound Stator Using Extended Electromotive Force Model Reviewed

Imai Koji, Doki Shinji, Fujii Kiyoshi, Jung Sukhawa

2018 IEEE INTERNATIONAL CONFERENCE ON INDUSTRIAL TECHNOLOGY (ICIT) page： 492-497 2018

Flight Path Planning of Multiple UAVs for Robust Localization near Infrastructure Facilities Reviewed

Maeda Keigo, Funabora Yuki, Doki Shinji, Doki Kae

IECON 2018 - 44TH ANNUAL CONFERENCE OF THE IEEE INDUSTRIAL ELECTRONICS SOCIETY page： 2522-2527 2018

Evaluation in Real World of the Measuring Position Determination for Visual Inspection using UAV Reviewed

Asa Kotaro, Funabora Yuki, Doki Shinji, Doki Kae

IECON 2018 - 44TH ANNUAL CONFERENCE OF THE IEEE INDUSTRIAL ELECTRONICS SOCIETY page： 2711-2716 2018

Analysis of an Application of the Extended Electromotive Force Model Based Position Sensorless Control on the Wound-Field Synchronous Motor with Dual-Three Phases in Standstill/Low Speed Region Reviewed

Wang Shen, Imai Koji, Doki Shinji

IECON 2018 - 44TH ANNUAL CONFERENCE OF THE IEEE INDUSTRIAL ELECTRONICS SOCIETY page： 5789-5794 2018

A Robust Neutral Point Potential Control for Single Phase Three Level Rectifier based on The Multiple Degree of Freedom Reviewed International journal

Guan Bo, Doki Shinji

2018 IEEE INTERNATIONAL CONFERENCE ON INDUSTRIAL TECHNOLOGY (ICIT) page： 606-611 2018

Design of band elimination filter for PMSM vector control operable in overmodulation region of inverter Reviewed International journal

Nakayama Y., Doki S.

IEEJ Transactions on Industry Applications Vol. 138 ( 11 ) page： 884 - 893 2018

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：IEEJ Transactions on Industry Applications

This paper proposes a filter design for improving the control performance of the current control system of Permanent Magnet Synchronous Motors (PMSMs) using the overmodulation region of an inverter. The control performance of a vector control system for PMSMs using the overmodulation region of an inverter can be improved by suppressing harmonic components that are generated in this region. This paper utilizes Band Elimination Filter (BEF) to eliminate harmonic components; however, unsuitable BEF setting leads to generation of large current oscillation at the resonant frequency of current feedback loop with BEF. In order to deal with these problems, the proposed filter design focuses on gain setting at the cutoff frequency of BEF. The proposed filter design can prevent the generation of current oscillation at the resonant frequency of the system, and can improve current control performance without complex adjustments. Simulations and experiments are carried out to show the effectiveness of the proposed BEF setting.

DOI： 10.1541/ieejias.138.884

Analysis of an Application of the Extended Electromotive Force Model Based Position Sensorless Control on the Wound-Field Synchronous Motor with Dual-Three Phases in Standstill/Low Speed Region Reviewed International journal

Wang Shen, Imai Koji, Doki Shinji

IECON 2018 - 44TH ANNUAL CONFERENCE OF THE IEEE INDUSTRIAL ELECTRONICS SOCIETY page： 5789-5794 2018

Evaluation in Real World of the Measuring Position Determination for Visual Inspection using UAV Reviewed

Asa Kotaro, Funabora Yuki, Doki Shinji, Doki Kae

IECON 2018 - 44TH ANNUAL CONFERENCE OF THE IEEE INDUSTRIAL ELECTRONICS SOCIETY page： 2711-2716 2018

EEMFs Excited by Signal Injection for Position Sensorless Control of PMSMs and Their Performance Comparison by Using Imaginary Electromotive Force Reviewed International journal

Nimura Takumi, Kondo Shota, Doki Shinji, Tomita Mutuwo

2018 INTERNATIONAL POWER ELECTRONICS CONFERENCE (IPEC-NIIGATA 2018 -ECCE ASIA) page： 1295-1300 2018

Prototype of Wearable Robot with Tactile Sensor Measurable Contact Force Distribution with User Reviewed International journal

Ito Daiki, Funabora Yuki, Doki Shinji, Doki Kae

2018 15TH INTERNATIONAL CONFERENCE ON CONTROL, AUTOMATION, ROBOTICS AND VISION (ICARCV) page： 960-965 2018

Position Sensorless Control for Wound-Field Synchronous Motor with Double Three-phase Wound Stator Using Extended Electromotive Force Model Reviewed International journal

Imai Koji, Doki Shinji, Fujii Kiyoshi, Jung Sukhawa

2018 IEEE INTERNATIONAL CONFERENCE ON INDUSTRIAL TECHNOLOGY (ICIT) page： 492-497 2018

Position Sensorless Control based on Pattern Matching Method using Multiple Template Data Sets to Improve Position Control Error Reviewed International journal

Song Hamin, Doki Shinji

2018 20TH EUROPEAN CONFERENCE ON POWER ELECTRONICS AND APPLICATIONS (EPE'18 ECCE EUROPE) page： . 2018

PMSM Model Discretization in Consideration of Park Transformation for Current Control System Reviewed International journal

Inoue Masamichi, Doki Shinji

2018 INTERNATIONAL POWER ELECTRONICS CONFERENCE (IPEC-NIIGATA 2018 -ECCE ASIA) page： 1228-1233 2018

New Search Algorithm of Model Predictive Control to Reducing Calculation Amount for Improving Steady Current Control Performance Reviewed International journal

Shimaoka Masahiro, Doki Shinji

2018 INTERNATIONAL POWER ELECTRONICS CONFERENCE (IPEC-NIIGATA 2018 -ECCE ASIA) page： 1747-1751 2018

Maximum Torque Control Reference Frame Based on a Torque Map for IPMSMs with Large Inductance Variation Reviewed International journal

Ohta Kazuki, Ohnuma Takumi, Doki Shinji

2018 INTERNATIONAL POWER ELECTRONICS CONFERENCE (IPEC-NIIGATA 2018 -ECCE ASIA) page： 1223-1227 2018

Initial Position Error Convergence of Position Sensorless Control of PMSM by using Extended Electromotive Force Excited by Signal Injection Reviewed International journal

Nimura Takumi, Kondo Shota, Doki Shinji, Tomita Mutuwo

2018 20TH EUROPEAN CONFERENCE ON POWER ELECTRONICS AND APPLICATIONS (EPE'18 ECCE EUROPE) page： . 2018

Majority Rule Sensor Fusion System with Particle Filter for Robust Robot Localization Reviewed International journal

Ohashi Nozomu, Funabora Yuki, Doki Shinji, Doki Kae

2018 IEEE/ASME INTERNATIONAL CONFERENCE ON ADVANCED INTELLIGENT MECHATRONICS (AIM) page： 1106-1111 2018

Improvement in Control Performance of PMSMs by Deactivation of Antiwindup Control in the Overmodulation Range of an Inverter Reviewed International journal

Nakayama Yosuke, Doki Shinji

2018 20TH EUROPEAN CONFERENCE ON POWER ELECTRONICS AND APPLICATIONS (EPE'18 ECCE EUROPE) page： . 2018

High Stability V/f Control of PMSM Using State Feedback Control Based on n-t Coordinate System Reviewed International journal

Matsuki Yosuke, Doki Shinji

2018 INTERNATIONAL POWER ELECTRONICS CONFERENCE (IPEC-NIIGATA 2018 -ECCE ASIA) page： 2224-2228 2018

High performance V/f control of PMSM using state feedback control based on n-t coordinate system Reviewed International journal

Matsuki Y., Doki S.

IEEJ Transactions on Industry Applications Vol. 138 ( 12 ) page： 911 - 919 2018

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：IEEJ Transactions on Industry Applications

This paper proposes a new V/f control method for permanent magnetic synchronous motors (PMSMs) without a position sensor. The proposed method uses state feedback control based on an n-t coordinate system, and controls rotational speed and the voltage amplitude. The t-axis is a tangent line of a constant voltage ellipse, and the n-axis is a normal line of the ellipse. The t-axis current is utilized to place the poles of the transfer function at the desired position at low speed and high speed conditions. The effectiveness of the proposed method was verified by simulation and experimental results.

DOI： 10.1541/ieejias.138.911

Flight Path Planning of Multiple UAVs for Robust Localization near Infrastructure Facilities Reviewed International journal

Maeda Keigo, Funabora Yuki, Doki Shinji, Doki Kae

IECON 2018 - 44TH ANNUAL CONFERENCE OF THE IEEE INDUSTRIAL ELECTRONICS SOCIETY page： 2522-2527 2018

The Multiple Degree of Freedom based Neutral Point Potential Control of Three Level Neutral Point Clamped Converters Reviewed

Guan Bo, Doki Shinji

2018 INTERNATIONAL POWER ELECTRONICS CONFERENCE (IPEC-NIIGATA 2018 -ECCE ASIA) page： 1032-1037 2018

A dual-degrees of freedom based PWM for single phase three level rectifiers with a strong neutral point potential control ability Reviewed International journal

Guan B., Doki S.

Proceedings IECON 2017 - 43rd Annual Conference of the IEEE Industrial Electronics Society Vol. 2017-January page： 527 - 532 2017.12

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：Proceedings IECON 2017 - 43rd Annual Conference of the IEEE Industrial Electronics Society

For the discussion about the neutral point potential (NPP) control of single phase three-level rectifiers, most of the methods solve the NPP problem by adjusting the zero-sequence voltage under symmetrical load conditions. However, when one phase voltage reaches to the maximum voltage, the other phase voltage goes to the minimal voltage. As a result, the NPP control ability is limited since there is no chosen zero-sequence voltage when the modulation ratio is close to 1. It can not be suitable for some strong asymmetrical load applications, in which two DC-link capacitors are used to drive different loads separately. In this paper, a dual-degrees of freedom based PWM is proposed, which can enhance the NPP control ability for single phase three level rectifiers. Introducing a new degree of freedom, the proposed method has more choices for the NPP control. It can decrease the NPP fluctuation under the strong asymmetrical load conditions, compared with the traditional PWM methods. The simulation results ratify the correctness and feasibility of the proposed PWM method finally.

DOI： 10.1109/IECON.2017.8216093

Measuring Position Determination for Accurate and Efficient Visual Inspection Using UAV Reviewed International journal

Asa Kotaro, Yuki Funabora, Shinji Doki, Kae Doki

Proc. of 2017 IEEE/SICE International Symposium on System Integration Vol. 2018-January ( ThA1.3 ) page： 188 - 193 2017.12

A novel neutral point potential balance control of three-level converters based on the search optimization method of dual degrees of freedom Reviewed International journal

Guan B., Doki S.

2017 19th European Conference on Power Electronics and Applications, EPE 2017 ECCE Europe Vol. 2017-January 2017.11

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：2017 19th European Conference on Power Electronics and Applications, EPE 2017 ECCE Europe

Even though the neutral point potential (NPP) balance problem of three-level neutral-point-clamped (NPC) converters can be solved by the traditional methods based on nearest-three-vectors (NTV) PWM, a low frequency fluctuation in the NPP will appear, which makes the capacitor reduction become hard. The dual modulation waves method is used to overcome the low frequency fluctuation, but it is an open-loop way, which will cause the drift voltage problem of the NPP and increase the switching frequency. Moreover, the control ability of the neutral point current is limited since the zero-sequence voltage is fixed. By removing the limit of the zero-sequence voltage and introducing a new degree of freedom, a novel NPP control of three-level NPC converters based on the search optimization is proposed in this paper. Fuzzing the boundary between the NTV-PWM and the dual modulation waves method, the proposed method realizes two modulations by a unified way. It can solve the low frequency fluctuation problem, reduce the switching frequency and extend the control ability of the neutral point current simultaneously by choosing the optimal dual degrees of freedom. Comparing the NTV-PWM, the dual modulation waves method and the proposed method, the simulation results verify the correctness and effectiveness of the proposed method.

DOI： 10.23919/EPE17ECCEEurope.2017.8098930

A study on position sensorless control without any q-axis inductance by using Extended Electromotive Force with High frequency signal injection Reviewed International journal

Kondo S., Doki S., Tomita M.

2017 19th European Conference on Power Electronics and Applications, EPE 2017 ECCE Europe Vol. 2017-January page： P1 - P6 2017.11

Language：English Publishing type：Research paper (international conference proceedings) Publisher：2017 19th European Conference on Power Electronics and Applications, EPE 2017 ECCE Europe

This paper describes sensitivity analysis to q-axis inductance variation of the position estimation using Extended Electromitive Force (EEMF) excited by High Frequency (HF) signal injection based on the mathematical formula evaluation, and it shows that the influence on the q-axis inductance variation is very small. Finally, experimental results indicate that position estimation can be performed well without any q-axis inductance information.

DOI： 10.23919/EPE17ECCEEurope.2017.8099118

Frequency-domain analysis for design of the current control system of PMSM based on model predictive control Reviewed International journal

Yokoyama S., Shimaoka M., Doki S.

2017 19th European Conference on Power Electronics and Applications, EPE 2017 ECCE Europe Vol. 2017-January page： P1 - P10 2017.11

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：2017 19th European Conference on Power Electronics and Applications, EPE 2017 ECCE Europe

This paper describes a method of deriving frequency characteristics of PMSM current control system based on Model Predictive Control (MPC). MPC controller predicts the current behavior using the mathematical model of PMSM and directly selects the optimal switch state based on evaluation of these predicted results. So, we have focused the possibility of MPC, which makes it possible to drive machines seamlessly between linear operating region of inverter and the overmodulation operating region. But, MPC is a nonlinear control system, so its frequency characteristics are unknown. In this paper, we derive MPC's frequency characteristic approximately through simulation to realize its frequency domain design.

DOI： 10.23919/EPE17ECCEEurope.2017.8099119

High Response Voltage Phase Torque Control of IPMSM for Both Linear and Over-modulation Range of Inverter Reviewed International journal

Matsuki Y., Doki S.

2017 19th European Conference on Power Electronics and Applications, EPE 2017 ECCE Europe Vol. 2017-January 2017.11

Language：English Publishing type：Research paper (international conference proceedings) Publisher：2017 19th European Conference on Power Electronics and Applications, EPE 2017 ECCE Europe

This paper proposes a high response voltage phase torque control method of interior permanent magnet synchronous motors for both linear and over-modulation range including six-step mode. In our proposed method, a new n-t coordinate system is utilized, on which voltage phase and amplitude are controlled responsively and stably.

DOI： 10.23919/EPE17ECCEEurope.2017.8098942

Position Sensorless Control for IPMSM of Spatial Inductance Distribution with Nonsinusoidal Inductance Waveform Based on Pattern Matching Method Reviewed International journal

Yuki Makaino, Shinji Doki

ELECTRICAL ENGINEERING IN JAPAN Vol. 201 ( 3 ) page： 35 - 42 2017.11

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY

This paper presents a novel pattern matching based position sensorless control method for IPMSMs. A target IPMSM for the proposed method is designed such that it has high power and torque density, while also being significantly influenced by magnetic saturation. As previously reported in papers , for IPMSMs, heavy magnetic saturation affects the spatial distribution of phase inductances according to rotor positions. Most position sensorless controls at low speeds typically depend on the assumption that phase inductances have sinusoidal spatial distribution according to rotor positions. Therefore, it is difficult to apply conventional methods to IPMSMs with heavy magnetic saturation. In the proposed method, rotor position is estimated by pattern matching using feature values, so that the phase inductances have unique and reproducible value according to rotor positions. While template data sets are required for the proposed method, the assumption for sinusoidal phase inductances is not. In this paper, the effect of magnetic saturation for position estimation based on conventional methods is discussed in Section 1 and 2. Then, details of the proposed method are shown in Section 3. In Section 4, results of experiments carried out in steady state and transient state are presented. The effectiveness of the proposed method is verified through the experiments.

DOI： 10.1002/eej.23008

A study of design method of full-order observer based on extended electromotive force for position sensorless control of IPMSMs Reviewed International journal

Toshiya Mabuchi, Ayame Makimura, Mutuwo Tomita, Shota Kondo, Masaru Hasegawa, Shinji Doki, Shinji Kato

2017 20th International Conference on Electrical Machines and Systems, ICEMS 2017 2017.10

Language：English Publishing type：Research paper (international conference proceedings) Publisher：Institute of Electrical and Electronics Engineers Inc.

Several position sensorless control methods of IPMSMs(Interior Permanent Magnet Synchronous Motors) using the observers have been proposed. In case of the full-order observers, these designs are difficult, because the order of the error equations of the observers becomes four. In this paper, for the position sensorless control of IPMSMs, a design method of the full-order observer based on the extended electromotive force (EEMF) is proposed. The experimental result shows that this design method of full-order observer is very useful.

DOI： 10.1109/ICEMS.2017.8056278

A suppression method of the low frequency fluctuation of the neutral point potential under 3-level SHEPWM based on 3-order harmonic Reviewed International journal

Guan B., Doki S.

2017 20th International Conference on Electrical Machines and Systems, ICEMS 2017 2017.10

Language：English Publishing type：Research paper (international conference proceedings) Publisher：2017 20th International Conference on Electrical Machines and Systems, ICEMS 2017

Even though some methods have been put forward to solve the drift problem and the low frequency fluctuation problem of the neutral point potential (NPP) for three level neutral point clamped converters (TL-NPC), they are all just suitable for SPWM or SVPWM technologies. In some medium/high voltage high power applications, where SHEPWM is utilized to modulate the reference voltages, the drift problem and the low frequency fluctuation problem of the NPP become difficult. The duty cycle of phase voltage waveforms under SHEPWM can't be adjusted after the switching angles were calculated based on the optimal harmonic limits. For the severe low frequency fluctuation of the NPP, a suppression method is raised based on 3-order harmonic amendment in this paper. 3-order harmonic has no effect on the output performances under 3-phase 3-wire systems, but it can regulate the NPP. By analyzing the relationship between the NPP and 3-order harmonic, an optimal 3-order harmonic is determined. Using the optimal 3-order harmonic to calculate the switching angles for SHEPWM, the low frequency fluctuation of the NPP is suppressed obviously, which is important to improve the output performances and to reduce Dc-link capacitors. The simulation is done to verify the correctness and feasibility of proposed method.

DOI： 10.1109/ICEMS.2017.8056223

Filter setting for improving torque control performance of IPMSMs in overmodulation region of inverter Reviewed International coauthorship International journal

Nakayama Y., Doki S.

2017 20th International Conference on Electrical Machines and Systems, ICEMS 2017 2017.10

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (international conference proceedings) Publisher：2017 20th International Conference on Electrical Machines and Systems, ICEMS 2017

This paper presents the filter setting for expand the operation range of IPMSMs in overmodulation region of inverter. To operate IPMSMs in the overmodulation region, it is necessary to deal with harmonics components. In this paper BSF is utilized to suppress the harmonic components, and its setting method is mentioned. The operation range in the overmodulation region is expanded appropriately by setting the filter focusing on resonant frequency of the system.

DOI： 10.1109/ICEMS.2017.8056395

Position sensorless control of synchronous reluctance motors at very low speeds region using high-frequency current control system Reviewed International journal

Toshiya Mabuchi, Ayame Makimura, Mutuwo Tomita, Shota Kondo, Masaru Hasegawa, Shinji Doki, Shinji Kato

2017 20th International Conference on Electrical Machines and Systems, ICEMS 2017 2017.10

Language：English Publishing type：Research paper (international conference proceedings) Publisher：Institute of Electrical and Electronics Engineers Inc.

Synchronous reluctance motors (SynRMs) have attracted studies, because SynRMs have no magnets in the rotors. The position sensorless control at low speeds of SynRMs is now desired, and several methods have been proposed. In this paper, by using the high-frequency current control system, a new position sensorless control method of SynRMs at low speeds by superimposing high-frequency current whose amplitude is small constant value has been proposed. The experiments show that the proposed method is very useful even if the very low speeds region.

DOI： 10.1109/ICEMS.2017.8055979

The compensation strategy on the drift voltage problem of dual modulation waves based neutral point potential control for three level converter Reviewed International journal

Guan B., Doki S.

IEEE International Symposium on Industrial Electronics page： 893 - 898 2017.8

Authorship：Lead author Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE International Symposium on Industrial Electronics

Even if the dual modulation waves based neutral-point-potential (NPP) control for three-level converters is able to eliminate the low frequency NPP fluctuation, it just has the natural balancing characters for the NPP. Thus, a compensation strategy is necessary to solve the drift voltage problem of the NPP. The traditional compensators overcome the drift voltage problem by adjusting an offset voltage. Since there is no theoretical basis to determine the gain of the offset voltage, it may cause the over-adjustment. It is also difficult to master the law of the output waveform adjusted by the offset voltage. Given these defects of the traditional compensators, a new compensation factor (CF) is raised and the relationship of the CF, the NPP, the phase current and the Dc-link capacitors is analyzed in this paper. By adjusting the CF in a limit region analyzed in this paper, the drift voltage problem is well solved without over-adjustment. Since it is easy to know the law of the output waveform adjusted by the new CF, it can also decrease the switching frequency and avoid the three level modulation degrading to the two level modulation in some operation conditions. Simulation results verify the correctness and effectiveness of the proposed method.

DOI： 10.1109/ISIE.2017.8001364

A study of position sensorelss control for IPMSM having non-sinusoidal inductance spatial distribution based on pattern matching method Reviewed International journal

Song H., Doki S.

2017 IEEE 3rd International Future Energy Electronics Conference and ECCE Asia, IFEEC - ECCE Asia 2017 page： 47 - 51 2017.7

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：2017 IEEE 3rd International Future Energy Electronics Conference and ECCE Asia, IFEEC - ECCE Asia 2017

A pattern matching method for position sensorless control of IPMSMs having non-sinusoidal inductance spatial distribution in standstill and very low speed region has been proposed. In the proposed method, the rotor position is estimated by comparing the phase current derivatives measured in a real-time with those in advanced. The current derivatives are obtained by measuring the phase currents twice at the certain voltage vector of inverter switching. The certain voltage vector not only must be created in all rotor position, but also must continue for at least a minimum time (tmin) to measure the currents twice. However there exists conditions which could not be secured tmin depending on the load current and the rotor position. In previous researches, switching-state phase shift method is utilized in order to create the certain voltage vector by injection high frequency voltage in all rotor position. In this paper, proposed various switching-state phase shift methods are explained and strong and weak points of each method are compared. Furthermore, the effectiveness and remaining issues of each methods are represented by experimental results.

DOI： 10.1109/IFEEC.2017.7992416

The characteristic evaluation of the method to improve the voltage phase resolution of model predictive control for current control system of PMSM Reviewed International journal

Shimaoka M., Yokoyama S., Doki S.

2017 IEEE 3rd International Future Energy Electronics Conference and ECCE Asia, IFEEC - ECCE Asia 2017 page： 1641 - 1645 2017.7

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：2017 IEEE 3rd International Future Energy Electronics Conference and ECCE Asia, IFEEC - ECCE Asia 2017

This paper describes new model predictive control for high performance current control system of PMSM. The current control system based on FCS-MPC decides an inverter output voltage directly by searching. In a principle, this type controller can use not only PWM drive but also overmodulation and square wave drive[1]. However, conventional current control based on FCS-MPC is inferior to PWM modulated PI base control in the steady control performance for the reason of this method that the voltage phase resolution is coarse. The improvement of the voltage phase resolution of FCS-MPC can't realize by the restriction of the equipment. So, we have proposed new model predictive control to improve the voltage phase resolution not depending the limitation of the device[2], [3]. In this paper, we evaluate the characteristics of propose method comparing conventional current control based on FCS-MPC by the simulation and experimentation.

DOI： 10.1109/IFEEC.2017.7992293

A new position sensorless control for IPMSM using feature values measured at zero voltage vector based on pattern matching method Reviewed International journal

Song H., Doki S.

Proceedings of the International Conference on Power Electronics and Drive Systems Vol. 2017-December page： 581 - 586 2017.7

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：Proceedings of the International Conference on Power Electronics and Drive Systems

This paper presents a position sensorless control method based on pattern matching method for high power density Interior Permanent Magnet Synchronous Motors (IPMSMs) that have non-sinusoidal inductance spatial distribution. In this paper, a new pattern matching method using feature values measured at zero voltage vector is proposed to improve the position estimation performance. By measuring the feature values at zero voltage vector, the number of feature value used in evaluation function is increased and it is advantageous for position sensorless control performance while keeping the wide operating range. Through experimental results, the effectiveness of the proposed method is presented.

DOI： 10.1109/PEDS.2017.8289201

The steady current characteristics of the voltage phase resolution of model predictive modulated current vector control for PMSM Reviewed International journal

Shimaoka M., Doki S.

Proceedings of the International Conference on Power Electronics and Drive Systems Vol. 2017-December page： 166 - 171 2017.7

Authorship：Last author Language：English Publishing type：Research paper (international conference proceedings) Publisher：Proceedings of the International Conference on Power Electronics and Drive Systems

We have proposed new Model Predictive Control which can design the voltage phase resolution and average switching frequency independently for improving steady control performance. Our propose method is based on FCS-MPC, the controller decides switching timing of each phase during control period directly by predicting future current behaviors at each prediction period and evaluate each behaviors. Shortening prediction period can improve steady current control performance, however, calculation amounts of prediction become huge and interfere with implementation. So, our method needs understanding the characteristics of voltage phase resolution and the necessary voltage phase resolution in each operation point for realizing a same level steady current control performance of PI base current vector control using PWM. In this paper, we describe the steady current characteristic of the voltage phase resolution of our method.

DOI： 10.1109/PEDS.2017.8289233

Impedance control system based on contact force distribution for wearable robot with tactile sensors Reviewed International journal

Sato A., Funabora Y., Doki S., Doki K.

SII 2017 - 2017 IEEE/SICE International Symposium on System Integration Vol. 2018-January page： 918 - 923 2017.7

Language：English Publishing type：Research paper (international conference proceedings) Publisher：SII 2017 - 2017 IEEE/SICE International Symposium on System Integration

The authors aim for safe assistance by feedback control of the contact force distribution in wearable robots. Since the wearable robot is in direct contact with the user, safety control is important. In order to improve safety, robot is desirable to be able to be controlled based on contact force: The force applied to the human body by the robot. A control system that feeds back joint torque as contact force has been proposed. However, since the joint torque is the resultant force of the contact force, there is a possibility that the dangerous contact force can not be detected directly. In this paper, the authors propose a new control system based on contact force distribution. The contact force distribution is sensed as pressure distribution by the tactile sensors attached to the robot surface. Impedance control in manipulator was expanded and applied to contact force distribution feedback control. The proposed method is compared with the control based on joint torque and the effectiveness of our method is verified.

DOI： 10.1109/SII.2017.8279340

An Extraction Method of Causality Patterns between Situation and Human Action with Delay Time for Statistical Modeling of Human Action

Kohjiro Hashimoto, Kae Doki, Shinji Doki

ELECTRONICS AND COMMUNICATIONS IN JAPAN Vol. 100 ( 7 ) page： 3 - 17 2017.7

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY

A modeling approach for human action is the focus of this paper. We design a human action model based on the stored data obtained during long-term monitoring of a person. This approach consists of the following two processes. First, several kinds of partial time series data that occur frequently are extracted from the stored data and taken to be human action patterns. Next, the extracted time series data are modeled based on a statistical modeling method such as the hidden Markov model. In this research, we focus on the extraction method for the time series data that occur frequently in the stored data. A person changes his actions according to changes in the situation around him. Moreover, it takes some time for him to perform his action after he recognizes the situation around himself. This time is called the delay time in this paper. A human action model that takes this delay time into consideration leads to greater accuracy in recognition and prediction of human actions based on that action. It is necessary to extract time series data for a situation and an action with the delay time as training data in order to generate the above human action model. In conventional methods, multidimensional time series data are used as the stored data without a distinction between the situation and action data. Also, some partial time series data that occur frequently are extracted from the stored data. Therefore, the delay time is not taken into account. In this paper, we propose a new extraction method for time series data that occur frequently with the time delay taken into consideration. In this method, sets of partial time series data that occur frequently with the delay time are extracted by evaluating the repeatability and similarity between the partial time series data sets with different occurrence frequencies. In the experiment, we extract the interaction motions that occur frequently between two subjects. The utility of the proposed method is examined based on the experimental results.

DOI： 10.1002/ecj.11961

パーティクルフィルタを用いた自己位置推定のロバスト性向上を目指した確率分布の類似性に基づく動的なセンサ統合 Reviewed

巣山慶太, 舟洞佑紀, 道木慎二, 道木加絵

計測自動制御学会論文集 Vol. 53 ( 2 ) page： 169 - 177 2017.2

Position sensorless for IPMSM with heavy magnetic saturation based on pattern matching method Reviewed International journal

Song H., Doki S.

19th International Conference on Electrical Machines and Systems, ICEMS 2016 2017.1

Language：English Publishing type：Research paper (international conference proceedings) Publisher：19th International Conference on Electrical Machines and Systems, ICEMS 2016

A pattern matching method for position sensorless control of IPMSM with heavy magnetic saturation in standstill and very low speed region has been proposed. The rotor position is estimated by comparing the feature values measured in a real-time with in beforehand. To measure feature values, high frequency signal must be injected. The operation region of pattern matching method is limited by amplitude of injectable signal. This paper presents the operating region that could utilize pattern matching method. Also to expand the operating region, a new signal injection method and matching method are proposed. By using the proposed method, the same sampling time interval for measuring feature values could be obtained even smaller signal is injected.

Position estimation system for PMSM position sensorless control in inverter overmodulation drive Reviewed International journal

Kosuke Kondo, Shinji Doki

IEEJ Journal of Industry Applications Vol. 6 ( 3 ) page： 165 - 172 2017

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：Institute of Electrical Engineers of Japan

This study investigates compensation methods for harmonic components to realize PMSM position sensorless control in inverter overmodulation drive. While applying PMSMs as traction motor motors in an EV or HEV, operating PMSM in inverter overmodulation drive is an effective method to widen high-speed drive region of PMSM and achieve fast torque response when voltage saturates because it enable to utilize 27% higher fundamental voltage as compared to linear drive. In addition, position sensorless control is regarded as an important technique for adding a fail-safe function and downsizing of the drive system. However, the harmonic components which are inevitably generated in inverter overmodulation drive have negative effects on closed current control and position estimation systems. The key to realize position sensorless control in inverter overmodulation drive is an appropriate compensation for the harmonic components in the input voltage and input current of a the position estimator. There are several methods to achieve this, and differences in position estimation performance possibly exist among these methods. In this study, the compensation methods for harmonic components in overmodulation drive are compared, and a suitable compensation method for sensorless control is investigated through an experiment.

DOI： 10.1541/ieejjia.6.165

A study on position sensorless control without any q-axis inductance by using Extended Electromotive Force with High frequency signal injection Reviewed

Kondo Shota, Doki Shinji, Tomita Mutuwo

2017 19TH EUROPEAN CONFERENCE ON POWER ELECTRONICS AND APPLICATIONS (EPE'17 ECCE EUROPE) page： . 2017

A New Position Sensorless Control for IPMSM Using Feature Values Measured at Zero Voltage Vector Based on Pattern Matching Method Reviewed

Song Hamin, Doki Shinji

2017 IEEE 12TH INTERNATIONAL CONFERENCE ON POWER ELECTRONICS AND DRIVE SYSTEMS (PEDS) page： 581-586 2017

Study on self-localization of an autonomous mobile robot using 2D maps generated with 3DLidar. Reviewed

DOKI Kae, SHINYA Ryu, FUNABORA Yuki, DOKI Shinji, TORII Akihiro, MOTOTANI Suguru

The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) Vol. 2017 page： 2P2 - D02 2017

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Society of Mechanical Engineers

<p>In this paper, we propose a self-localization method of an autonomous mobile robot using multiple 2D maps generated with information from 3D Lidar. In this method multiple 2D maps are generated with 3D point cloud divided into some groups based on the height from the ground. Then, multiple probability distributions for self-localization are generated with particle filter. The result of self-localization is calculated by selection and integration of the probability distributions based on KL divergence.</p>

DOI： 10.1299/jsmermd.2017.2P2-D02

Automatic Measuring Position Determination of UAVs for Visual Inspection System of Infrastructures Based on 3D Construction Model Considering Accuracy of Data Reviewed

ASA Kotaro, FUNABORA Yuki, DOKI Shinji, DOKI Kae

Transactions of the Society of Instrument and Control Engineers Vol. 53 ( 3 ) page： 229 - 235 2017

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Society of Instrument and Control Engineers

This paper presents a measuring-position-determination method of Unmanned Aerial Vehicles (UAVs) for automatic visual inspection system. In the proposed method, it is assumed that 3D model of the target infrastructure, the specification of measurement and UAV's features are given. Under those assumptions, the measuring positions are calculated considering the accuracy of data. In this paper, the usefulness of the proposed method is examined by a computer simulation assuming visual inspections for several bridges. In the simulation, measuring positions are determined assuming several types of UAVs for each bridge.

DOI： 10.9746/sicetr.53.229

Robust Localization based on Integration of Position Information from Subsidiary UAVs Reviewed

MAEDA Keigo, FUNABORA Yuki, DOKI Shinji, DOKI Kae

The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) Vol. 2017 page： 2P2 - C02 2017

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Society of Mechanical Engineers

<p>In order to realize automatic inspection for infrastructure facilities using Unmanned Aerial Vehicles(UAVs), improvement robust localization of UAVs is needed. Especially, automatic flight could not be work in environments near facilities such as under the bridges. In this research, localization method is studied based on integration of position information gathering from subsidiary UAVs located in the surroundings of a main UAV. In this paper, as the first stage of this study, probabilistic position estimation model of subsidiary UAVs is modeled and integrated based on joint probability. By simulations with the models, influences of both position estimation errors of subsidiary UAVs and measurement errors of relative position are considered.</p>

DOI： 10.1299/jsmermd.2017.2P2-C02

A New Position Sensorless Control for IPMSM Using Feature Values Measured at Zero Voltage Vector Based on Pattern Matching Method Reviewed International journal

Song Hamin, Doki Shinji

2017 IEEE 12TH INTERNATIONAL CONFERENCE ON POWER ELECTRONICS AND DRIVE SYSTEMS (PEDS) page： 581-586 2017

Sensor Fusion System for Mobile Robot Localization Using Fault Detection Similarity Evaluation of Probability Distribution for Fault Detection Reviewed

OHASHI Nozomu, FUNABORA Yuki, DOKI Shinji, DOKI Kae

The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) Vol. 2017 page： 2P2 - C01 2017

Language：Japanese Publishing type：Research paper (other academic) Publisher：The Japan Society of Mechanical Engineers

<p>To realize robust localization of mobile robot, it is important to improve method of integrating position information from various sensors whose dependence on environment is different. In the case of probability localization, such as particle filter, simultaneous probability is used. However, when a sensor is affected by huge noises such as multipath of GPS, simultaneous probability is incorrect. The authors have proposed selective sensor fusion system based on similarity of distributions. This paper proposes a new similarity evaluation method analyzing particles sampled from distribution and verifies its effectiveness by real world localization.</p>

DOI： 10.1299/jsmermd.2017.2P2-C01

Measuring Position Determination using Vector Quantization for Automatic Inspection Systems using UAVs Reviewed

ASA Kotaro, FUNABORA Yuki, DOKI Shinji, DOKI Kae

The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) Vol. 2017 page： 1P1 - C01 2017

Language：Japanese Publishing type：Research paper (other academic) Publisher：The Japan Society of Mechanical Engineers

<p>Maintenance of infrastructures is a major problem. In order to streamline it, automation of inspections is researched. For complete automation, the measuring position determination method of inspection machines is necessary. This paper presents a method of measuring position determination using vector quantization for automatic visual inspection systems using Unmanned Aerial Vehicles (UAVs). In the proposed method, it is assumed that the 3D model of the target infrastructure, the specification of measurement and UAV's features are given. Under those assumptions, the 3D model is regarded as the cluster of vectors and the measuring positions are determined using vector quantization. In this paper, the proposed method is compared with the conventional method by a computer simulation assuming visual inspections.</p>

DOI： 10.1299/jsmermd.2017.1P1-C01

A study on position sensorless control without any q-axis inductance by using Extended Electromotive Force with High frequency signal injection Reviewed International journal

Kondo Shota, Doki Shinji, Tomita Mutuwo

2017 19TH EUROPEAN CONFERENCE ON POWER ELECTRONICS AND APPLICATIONS (EPE'17 ECCE EUROPE) page： . 2017

Predictive control of contact state in wearable robot for torso equipped with pressure distribution sensor Reviewed

SATO Asuka, FUNABORA Yuki, UCHIYAMA Naoya, DOKI Shinji, DOKI Kae

The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) Vol. 2017 page： 1P2 - K11 2017

Language：Japanese Publishing type：Research paper (conference, symposium, etc.) Publisher：The Japan Society of Mechanical Engineers

<p>The authors aim to realize assistance of complicated body parts as the torso. Securing safety for users is the utmost importance for wearable robots. For safer assistance, it is desirable to directly control the contact state. The contact state is acquired from the pressure distribution sensor on the robot surface, and the robot is controlled to reduce superfluous pressures. In this paper, a novel control method based on predictive is proposed. From current joint angles and pressure distribution of the robot, this method predicts and controls the pressure distribution of the next step. The proposed method is compared with the conventional joint torque control method and the effectiveness of our method is verified.</p>

DOI： 10.1299/jsmermd.2017.1P2-K11

Body Surface Measurement System with Multiple Kinect Sensors for Design of Wearable Robots with Tactile Sensor Reviewed

ITO Daiki, FUNABORA Yuki, DOKI Shinji, DOKI Kae

The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) Vol. 2017 page： 1P2 - J07 2017

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Society of Mechanical Engineers

<p>Safety control is considered to be the prior requirement for wearable assist robots. In response to the requirement, a control system based on pressure distribution has been researched. However, a robot structure suitable for the control method measured by tactile sensor has not been cleared. In this paper, in order to consider a suitable structure for wearable assist robots with tactile sensor 3D body surface measurement system is presented. The system consists multiple Kinect v2 sensors to measure user's body surface as high densely point cloud data.By fitting some candidate polygons to the data, a suitable polygon will be determined.</p>

DOI： 10.1299/jsmermd.2017.1P2-J07

Study on the model structure of human machine operation to evaluate a coincident timing skill Reviewed

Kohjiro Hashimoto, Kae Doki, Shinji Doki

IEEJ Transactions on Electronics, Information and Systems Vol. 137 ( 10 ) page： 1353 - 1363 2017

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Institute of Electrical Engineers of Japan

With an increase in the elderly population, traffic accidents caused by elderly drivers have become an important social issue in Japan. The primary factor of traffic accidents by elderly drivers is a reduction in their driving skill. Therefore, elderly drivers are required by law to conduct regularly a driving aptitude tests in Japan. If the driving skill of the driver is inadequacy, he is subject to punishment, such as driver license revoked. However, there is not appropriate evaluation index of driving skill. We have proposed a modeling method of driving behavior to support one. Proposed driving behavior model is generated based on the actual driving data of driver, and the generated model has some kind of habit and pattern of the driver. Therefore, it is considered that it is possible to evaluate driving skill of driver by analyzing the generated model. According this reason, we aim to propose a modeling method of driving behavior to evaluate driving skill. Here, a coincident timing skill of driver is focused as a driving skill. In the case of driving behavior, the execution timing of driving operations is decided based on the prediction of subsequent change of the outside environment information. The accuracy of this decided execution timing of operation depend on the above prediction is called as the coincident timing skill. In the proposed model, the causality between the situation around a person and operation of driver is modeled by Hidden Markov Model, and timing probability distribution is added to Hidden Markov Model in order to evaluate this coincident timing skill. The timing probability distribution expresses the execution timing of next operation of driver. Therefore, it is possible to detect the information of the coincident timing skill of driver from the timing probability distribution. In the experiment, the controller operation of a radio controlled vehicle is modeled by the proposed method, and the usefulness of the proposed model is examined through some experimental results.

DOI： 10.1541/ieejeiss.137.1353

Initial Position Estimation for IPMSMs Using Comb Filters and Effects on Various Injected Signal Frequencies Reviewed

Toshiki Suzuki, Masaru Hasegawa, Mutuwo Tomita, Shinji Doki

IEEJ Journal of Industry Applications Vol. 4 ( 3 ) page： 204-211 2015.5

Improved PMSM Model Considering Flux Characteristics for Model Predictive-Based Current Control Reviewed

Akihiro Imura, Tomoya Takahashi, Masami Fujitsuna, Tadanao Zanma, Shinji Doki

IEEJ Trans. on Electrical and Electronic Engineering Vol. 10 ( 1 ) page： 92–100 2015.1

高巻線係数と高占積率を両立する新しい巻線構造を持つ永久磁石同期モータ

牧田真治,伊藤靖英,青山知弘,道木慎二

電気学会論文誌D Vol. 134 ( 12 ) page： 1031-1037 2014.12

三次元磁路と環状巻線からなる簡素なステータ構造を有する新しいモータ Reviewed

牧田真治, 高橋英介, 梨木政行, 道木慎二

電気学会論文誌Ｄ Vol. 134 ( 3 ) page： 363-369 2014.3

Refinement of inverter model considering dead-time for performance improvement in predictive instantaneous current control

Akihiro Imura, Tomoya Takahashi, Masami Fujitsuna, Tadanao Zanma, Shinji Doki

IEEJ Trans. on Electrical and Electronic Engineering Vol. 9 ( 1 ) page： 83–89 2014.1

Position Sensorless Control of IPMSMs using Full-Order Flux Observer Based on an Algebraic Design Method

Atsushi Matsumoto, Masaru Hasegawa, Mutuwo Tomita, Shinji Doki

IEEJ Journal of Industry Applications Vol. 2 ( 3 ) page： 141-149 2013.5

サービスロボットの構造変化に対する適応動作の高速生成

舟洞　佑記,矢野　良和,道木　慎二,大熊　繁

日本機械学会論文集Ｃ編 Vol. 78 ( 793 ) page： 152-163 2012.9

センサレス制御やパラメータ同定のための信号重畳に適した電流制御系 Reviewed

鄭淅化, 大沼巧, 道木慎二, 大熊繁, 藤綱雅己

電気学会論文誌Ｄ部門 Vol. 132 ( 3 ) page： 418-425 2012.3

サービスロボットの機械的な構造変化に対する自律的な動作適応

舟洞　佑記,矢野　良和,道木　慎二,大熊　繁

日本機械学会論文集ｃ編 Vol. 78 ( 786 ) page： 583-594 2012.2

Estimation of next action and its timing based on the human action model considering time series information of the situation Reviewed

K. Hashimoto S. Doki K. Doki

Journal of Artificial Intelligence and Soft Computing Research Vol. 2 ( 3 ) page： 223-233 2012.1

サービスロボットの動作適応における動作の自己評価法

舟洞　佑記,矢野　良和,道木　慎二,大熊　繁

電気学会論文誌C Vol. 131 ( 12 ) page： 2072-2081 2011.12

永久磁石同期モータの電流制御系に対するモデル予測制御の適用

門田充弘，道木慎二，大熊繁

電気学会論文誌C Vol. 131-C ( 4 ) page： 860-869 2011.4

状況と行動の因果関係に着目した人間の行動モデル化手法─多次元時系列信号で表現された状況と離散事象で表現された行動の場合─

橋本幸二郎，道木加絵，道木慎二，大熊繁，鳥井明宏

電気学会論文誌C Vol. 131-C ( 3 ) page： 635-643 2011.3

拡張誘起電圧オブザーバによる位置センサレス制御の低速駆動域拡大

大沼巧,道木慎二,大熊繁

電気学会論文誌D Vol. 131-D ( 2 ) page： 208-218 2011.2

SynRMのセンサレス制御のための空間高調波モデリング手法

鄭淅化，小林久晃，道木慎二，大熊繁，藤綱雅己

電気学会論文誌D Vol. 131-D ( 2 ) page： 171-179 2011.2

IPMSMの最大トルク応答のための電流指令値計算法

Lerdudonsak Smith，道木慎二，大熊繁

電気学会論文誌D Vol. 131-D ( 1 ) page： 45-52 2011.1

Voltage Limiter Calculation Methods for Fast Torque Response of IPMSM in Overmodulation Range

IEEJ Transaction on Electrical and Electronics Engineering Vol. 5 ( 5 ) page： 586-595 2010.8

インバータの過変調領域で動作可能なPMSMの電流制御系 Reviewed

Lerdudonsak Smith,道木慎二、大熊繁

電気学会論文誌Ｄ Vol. 130 ( 5 ) page： 579-598 2010.5

拡張誘起電圧オブザーバのインダクタンス設定のみで実現する最大トルク制御 Reviewed

大沼巧，鄭淅化，道木慎二，大熊繁

電気学会論文誌D Vol. 130 ( 2 ) page： 158-165 2010.2

感情遷移における急激な韻律特徴変化の検出による感情遷移判別法 Reviewed

多田和彦，矢野良和，道木慎二，大熊繁

日本知能情報ファジィ学会誌 Vol. 22 ( 1 ) page： 90‐101 2010.1

人間の感情評価をモデル化した感情表現ルールに基づく感情動作生成 Reviewed

矢野良和，山口淳嗣，道木慎二，大熊繁

日本知能情報ファジィ学会誌 Vol. 22 ( 1 ) page： .39-51 2010.1

中性点電圧に現れる回転子スロット高調波を利用した超高速駆動誘導電動機の速度推定法

西端幸一，石田宗秋，道木慎二，増澤高志，藤綱雅巳

電気学会論文誌D Vol. 129-D ( 1 ) page： 1-9 2009.1

ΔΣ変調に基づく1 ビット信号処理の為の状態空間表現上におけるディジタルフィルタ設計法

伊藤悠二，道木慎二，大熊繁

電気学会論文誌Ｃ Vol. 128-C ( 12 ) page： 1781-1788 2008.12

*電圧飽和領域におけるIPMSMの高トルク応答のための新しい電圧リミッタ計算法

Lerdudonsak Smith，道木慎二，大熊繁

電気学会論文誌Ｄ Vol. 128-D ( 12 ) page： 1346-1356 2008.12

PMSMのセンサレス制御系におけるフレーム振動抑制制御法

島田有礼，河合健司，残間忠直，道木慎二，石田宗秋

電気学会論文誌D Vol. 128-D ( 11 ) page： 1246-1253 2008.11

Pulsed Neural Networks Based on Delta-Sigma modulation and Their Hardware Implementation Invited

Shinji DOKI, Yuji Ito and Shigeru Okuma

The Brain & Neural Networks Vol. 15 ( 1 ) page： 39-37 2008.1

遺伝的アルゴリズムを用いた永久磁石同期電動機の高周波等価回路の回路定数算定

伊藤康平，佐藤靖之，残間忠直，道木慎二，石田宗秋

電気学会論文誌D Vol. 127-D ( 3 ) page： 300-307 2007.3

ハイブリット電気自動車における電気技術 Invited

大熊繁，寺谷達夫，道木慎二

電気学会論文誌D Vol. 127-D ( 2 ) page： 98-101 2007.2

*焼嵌めによる損失を低減するための電磁鋼板の特性を用いた固定子形状の改善

佐藤光彦金子清一冨田睦雄道木慎二大熊繁

電気学会論文誌D Vol. 127-D ( 1 ) page： 60-68 2007.1

切り換え動作を伴う電力変換器へのモデル予測制御の適用について

残間忠直，福田純一，道木慎二，石田宗秋，大熊　繁，松本敬史，西森英二

電気学会論文誌C Vol. 127-C ( 2 ) page： 264-273 2007.1

Sensorless Control of Synchronous Reluctance Motors Based on an Extended EMF Model Considering Magnetic Saturation With an On-line Parameter Identification

Shinji Ichikawa, Mutsuwo Tomita, Shinji DOKI, Shigeru OKUMA

IEEE Transaction on Industrial Apprications Vol. 42 ( 5 ) page： 1264-1274 2006.9

*New approach for stability improvement of speedsensorless induction-motor controls at zero frequency using multirate adaptive observer

N. Yamaguchi, M. Hasegawa, S. Doki and S. Okuma

Vol. 153 ( 4 ) page： 544-550 2006.7

Sensorless control of interior permanent magnet synchronous motors using on-line parameter identification based on system identification theory

Shinji Ichikawa, Mutsuwo Tomita, Shinji DOKI, Shigeru OKUMA

IEEE Transaction on Industrial Electronics Vol. 53 ( 2 ) page： 363-372 2006.4

システム同定に基づく永久磁石同期電動機の高周波数式モデルの同定

伊藤康平道木慎二石田宗秋

電気学会論文誌D Vol. 126-D ( 1 ) page： 17-24 2006.1

ΔΣ変調に基づく1ビット信号処理における高次のフィルタ実現

村橋善光道木慎二大熊繁

電気学会論文誌C Vol. 125-C ( 12 ) page： 1891-1899 2005.12

*ΔΣ変調に基づくパルスニューラルネットワークによるＢＰ学習の実現とそのハードウエア実装

奥田忠義,道木慎二，石田宗秋

電子情報通信学会論文誌 Vol. J88-D-II ( 4 ) page： 778-787 2005.4

拡張誘起電圧モデルに基づくシンクロナスリラクタンスモータのセンサレス制御とそれに適したインダクタンス測定法

市川真士冨田睦雄道木慎二大熊繁

電気学会論文誌D Vol. 125-D ( 1 ) page： 16-25 2005.1

PMSM制御性能改善のための繰返し制御を用いた高調波電流抑制

金貞成道木慎二石田宗秋

電気学会論文誌D Vol. 124-D ( 12 ) page： 1189-1196 2004.12

位置推定精度に依存しないオンラインパラメータ同定法とそれを用いたシンクロナスリラクタンスモータのセンサレス制御

岩田昭寿市川真士冨田睦雄道木慎二大熊繁

電気学会論文誌D Vol. 124-D ( 12 ) page： 1205-1211 2004.12

ΔΣ変調に基づくパルスニューラルネットワークによるICAの実現とそのハードウエア実装

堀田博久村橋善光道木慎二大熊繁

電気学会論文誌C Vol. 124-D ( 11 ) page： 2288-2295 2004.11

拡張誤差に基づく速度・一次抵抗同定法による全領域で安定な速度センサレスベクトル制御

浜島豊和長谷川勝道木慎二大熊繁

電気学会論文誌D Vol. 124-D ( 8 ) page： 750-759 2004.8

PWMインバータ駆動永久磁石同期電動機の高周波等価回路

藤正一，道木慎二，石田宗秋

電気学会論文誌D Vol. 124-D ( 5 ) page： 464-470 2004.5

GHA学習則を組み込んだΔΣ変調に基づくパルスニューラルネットワークとそのハードウエア実装

村橋善光道木慎二大熊繁

電子情報通信学会論文誌 Vol. J87-DII ( 2 ) page： 705-715 2004.2

シンクロナスリラクタンスモータにおける拡張誘起電圧モデルとその主磁束方向の選択法

市川真士冨田光雄道木慎二大熊繁藤原文治

電気学会論文誌D Vol. 123-D ( 12 ) page： 1507-1515 2003.12

高周波電圧・電流を用いた外乱オブザーバによるシンクロナンスリラクタンスモータの位置・速度センサレス制御

玉置雅和冨田睦雄陳志謙道木慎二大熊繁

電気学会論文誌D Vol. 123-D ( 12 ) page： 1544-1545 2003.12

Robust Vector Control of Induction Motors Using Full-Order Observer in Consideration of Core Loss

M.Hasegawa,S.Furutani,S.Doki,S.Okuma

IEEE Transactions on Industrial Electronics Vol. 50 ( 5 ) page： 912-919 2003.10

フーリエ変換と繰返し制御を用いた高調波電流抑制によるIPMSMセンサレス制御系の特性改善

金貞成道木慎二石田宗秋

電気学会論文誌D Vol. 123-D ( 10 ) page： 1176-1184 2003.10

うず電流を用いた円筒形ブラシレスDCモータの低速時における位置・速度センサレス制御

高島大冨田睦雄陳志謙道木慎二佐藤光彦大熊繁

電気学会論文誌D Vol. 123-D ( 6 ) page： 762-763 2003.6

*An Extended Electromotive Foece Model for Sensorless Control fo Interior Permanet-Magnet Synchronous Motors

Zhiqian ChenShinji IchikawaMutuwo TomitaShinji DokiShigeru Okuma

IEEE Transactions on Industrial Electronics Vol. 50 ( 2 ) page： 288-295 2003.4

拡張誘起電圧モデルに基づく突極型永久磁石同期モータのセンサレス制御

市川真士陳志謙冨田光雄道木慎二大熊繁

電気学会論文誌D Vol. 122-D ( 12 ) page： 1088-1096 2002.12

ΔΣに基づくパルスニューラルネットワークとそのGHA学習則

村橋善光道木慎二大熊繁

電気学会論文誌C Vol. 122-C ( 10 ) page： 1821-1829 2002.10

誘導電動機のトルク制御精度の解析方法

金原義彦長谷川勝道木慎二大熊繁

日本AEM学会 Vol. 10 ( 3 ) page： 299-304 2002.9

ΔΣ変調に基づくパルスニューラルネットワークにおける1bit信号同士の演算の実現

村橋善光道木慎二大熊繁

情報技術レターズ Vol. 1 ( 1 ) page： 121-122 2002.9

γ-正実化問題とゲインスケジュールドH∞制御を用いた軸ずれを抑圧する同一次元オブザーバのロバスト設計法

長谷川勝道木慎二大熊繁

電気学会論文誌D Vol. 121-D ( 12 ) page： 1218-1227 2001.12

抵抗変動にロバストな最適オブザーバを用いた誘導電動機のベクトル制御法

金原　義彦道木　慎二大熊　繁

電気学会論文誌D Vol. 121-D ( 8 ) page： 902-907 2001.8

シグモイド関数付きニューロンモデルの反復演算法

中條直也黒柳奨道木慎二大熊　繁

電気学会論文誌Ｃ Vol. 122-C ( 3 ) page： 381-389 2001.3

多次元二分探索に基づくニューロン演算法

中條直也黒柳奨道木慎二大熊繁

電気学会論文誌C Vol. 121-C ( 2 ) page： 315-322 2001.2

ロバスト磁束オブザーバを用いたベクトル制御誘導電動機の固定子鉄損補償法

長谷川勝山崎尚徳道木慎二大熊繁

電気学会論文誌D Vol. 120-D ( 11 ) page： 1305-1312 2000.11

New Adaptive Sliding Observers for Position- and Velocity-SensorlessControls of Brushless DC Motors

Zhiqian Chen,Mutuwo TomitaShinji DokiShigeru Okuma

IEEE Transactions on Industrial Electronics Vol. 47 ( 3 ) page： 582-591 2000.6

確定的アニーリングと等ひずみ原理を融合した新しいベクトル量子化アルゴリズム

芳澤伸一道木慎二大熊繁

電気学会論文誌C Vol. 119-C ( 8/9 ) page： 1010-1017 1999.8

磁束オブザーバによるロバストベクトル制御系の実現とその特性評価

長谷川　勝山崎　尚徳道木慎二大熊繁

電気学会論文誌D Vol. 119-D ( 7 ) page： 932-941 1999.7

記憶容量の制約下での追加学習を目的とする新しい連想記憶システムの提案

芳澤伸一道木慎二大熊　繁

電子情報通信学会論文誌 Vol. J82-DII ( 6 ) page： 1072-1081 1999.6

変化する入力データに対する学習の定常特性と過渡特性を改善する新しいベクトル量子化アルゴリズム

芳澤伸一道木慎二大熊　繁

電子情報通信学会論文誌 Vol. J82-DII ( 4 ) page： 807-817 1999.4

逐次記憶学習を目的とした連想記憶システムへの「記憶パターンの信頼度」の利用

芳澤伸一道木慎二大熊　繁

電子情報通信学会論文誌 Vol. J81-DII ( 7 ) page： 1647-1655 1998.7

外乱オブザーバと速度適応同定による円筒形ブラシレスDCモータの位置・速度センサレス制御

陳　志謙冨田陸雄千住智信道木慎二大熊　繁

電気学会論文誌D Vol. 118-D ( 7/8 ) page： 828-835 1998.7

うず電流を利用した円筒形ブラシレスDCモータの不特定負荷時におけるセンサレス始動法及び低速駆動法

冨田陸雄山口英之道木慎二大熊　繁

電気学会論文誌D Vol. 118-D ( 4 ) page： 450-459 1998.4

うず電流による開放相電圧変化を利用した円筒形ブラシレスDCモータのセンサレス停止位置推定法

冨田陸雄山口英之道木慎二大熊　繁

電気学会論文誌D Vol. 117-D ( 10 ) page： 1205-1211 1997.10

Slip-Frequency Type and Flux-Feedback Type Vector Controls In Discrete-Time System

S.DokiK.TakahashiS.Okuma

IEEE Transactions on Industrial Electronics Vol. 44 ( 3 ) page： 382-389 1997.6

インテリジェントモーションコントロールⅠ．モータドライブにおける現状技術 Invited

大熊繁，道木慎二

電気学会論文誌D Vol. 116-D ( 8 ) page： 808-811 1996.8

Sensorless rotor-position estimation using eddy currents for cylindrical brushlessDC motors at standstill

M.TomitaM.SatohH.YamaguchiS.DokiS.Okuma

ELECTROMOTION Vol. 3 ( 2 ) page： 72-76 1996.4

うず電流を用いた円筒形ブラシレスＤＣモータのセンサレス位置推定法

冨田睦雄佐藤光彦山口秀之道木慎二大熊繁

電気学会論文誌Ｄ Vol. 116-D ( 3 ) 1996.3

適応スライディングオブザーバによるブラシレスＤＣモータのための位置・速度センサレス制御

冨田睦雄道木慎二大熊繁

電気学会論文誌Ｄ Vol. 115-D ( 6 ) page： 765-774 1995.6

外乱オブザーバを用いたブラシレスＤＣモータのセンサレスベクトル制御

千住智信富田睦雄道木慎二大熊繁

電気学会論文誌Ｄ Vol. 114-D ( 5 ) page： 591-592 1994.5

磁束オブザーバを用いた磁束フィードバック形と等価なすべり周波数形ベクトル制御

金原義彦道木慎二S.Sangwongwanich大熊繁

電気学会論文誌Ｄ Vol. 114-D ( 3 ) page： 315-324 1994.3

ロバスト設計法にもとづく磁束オブザーバを用いた磁束フィードバック形ベクトル制御系の実験

道木慎二S.Sangwongwanich大熊繁

電気学会論文誌Ｄ Vol. 114-D ( 3 ) page： 282-288 1994.3

Adaptive Sliding Observers for Induction Motor Control

S.SangwongwanichS.DokiT.YonemotoT.FuruhashiS.Okuma

Vol. 27 ( 5 ) page： 569-576 1991.5

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