Country：Japan

Country：Japan

Award type：Honored in official journal of a scientific society, scientific journal  Country：Japan

Award type：Award from Japanese society, conference, symposium, etc.  Country：Japan

Award type：International academic award (Japan or overseas)  Country：Australia

Award type：Award from international society, conference, symposium, etc.  Country：Japan

Award type：Award from international society, conference, symposium, etc.  Country：Japan

Award type：Award from Japanese society, conference, symposium, etc.  Country：Japan

Award type：Award from Japanese society, conference, symposium, etc.  Country：Japan

Award type：Honored in official journal of a scientific society, scientific journal  Country：Japan

Award type：Award from Japanese society, conference, symposium, etc.  Country：Japan

Country：Japan

Country：Japan

牧田真治

Award type：Honored in official journal of a scientific society, scientific journal  Country：Japan

井村　彰宏

Country：Japan

Country：Japan

Country：Japan

Country：Japan

モデル予測制御に基づくPMSMのトルク制御におけるデッドタイム補償　前田拓真

Country：Japan

Country：Japan

Country：Japan

Country：Japan

Country：Japan

Country：Japan

Country：Japan

Country：Japan

Country：Japan

Country：Japan

Country：Japan

Country：Japan

Country：Japan

Country：Japan

Country：Japan

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

Scopus

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

Scopus

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

Scopus

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

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Scopus

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

Scopus

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

Scopus

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

Scopus

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

Scopus

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

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Scopus

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

Scopus

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

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Scopus

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

Scopus

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

Scopus

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

Scopus

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

Scopus

Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

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

DOI： 10.1541/ieejeiss.141.193

Scopus

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

Scopus

Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

Authorship：Last author,　Corresponding 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

Web of Science

Scopus

Language：English   Publishing type：Research paper (international conference proceedings)  

DOI： 10.1109/IECON48115.2021.9589696

Web of Science

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

Scopus

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

DOI： 10.23919/ICEMS50442.2020.9291103

Scopus

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

Scopus

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

Scopus

Language：Japanese   Publishing type：Research paper (scientific journal)   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

Scopus

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

DOI： 10.23919/ICEMS50442.2020.9291246

Scopus

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

Scopus

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

Scopus

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

Scopus

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

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

DOI： 10.1109/GPECOM49333.2020.9247941

Scopus

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

DOI： 10.1109/IECON43393.2020.9254577

Scopus

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Authorship：Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

Authorship：Last author   Language：Japanese   Publishing type：Research paper (scientific journal)  

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

DOI： 10.1541/ieejias.140.589

Scopus

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

Scopus

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

Scopus

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

Scopus

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

Scopus

Authorship：Last author   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

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Scopus

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

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

Scopus

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Authorship：Last author   Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1109/TIE.2018.2851995

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Scopus

Authorship：Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.1002/eej.23202

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1002/eej.23198

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1002/eej.23175

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Authorship：Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.6113/JPE.2019.19.1.119

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

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

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

DOI： 10.1541/ieejeiss.139.1325

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

DOI： 10.1541/ieejeiss.139.1389

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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

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

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DOI： DOI: 10.1177/1729881419876794

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

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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

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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

Scopus

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

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

Language：English   Publishing type：Research paper (international conference proceedings)  

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

Scopus

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

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Publishing type：Research paper (scientific journal)   Publisher：IEEE International Symposium on Industrial Electronics  

DOI： 10.1109/ISIE.2018.8433732

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Publishing type：Research paper (scientific journal)   Publisher：ITEC Asia-Pacific 2018 - 2018 IEEE Transportation Electrification Conference and Expo, Asia-Pacific: E-Mobility: A Journey from Now and Beyond  

DOI： 10.1109/ITEC-AP.2018.8432597

Scopus

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

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Publishing type：Research paper (international conference proceedings)   Publisher：Proceedings of the IEEE International Conference on Industrial Technology  

DOI： 10.1109/ICIT.2018.8352247

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Language：Japanese   Publishing type：Research paper (scientific journal)   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

Scopus

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

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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

Scopus

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

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Publishing type：Research paper (scientific journal)   Publisher：31st International Electric Vehicle Symposium and Exhibition, EVS 2018 and International Electric Vehicle Technology Conference 2018, EVTeC 2018  

Scopus

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

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

DOI： 10.1541/ieejias.138.563

Scopus

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

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

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

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

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Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Authorship：Last author   Language：English   Publishing type：Research paper (international conference proceedings)  

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

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Authorship：Last author,　Corresponding 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

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

DOI： 10.23919/EPE17ECCEEurope.2017.8099118

Scopus

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

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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

Scopus

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   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

Scopus

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

Scopus

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

Scopus

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

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.9746/sicetr.53.169

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

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

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

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Authorship：Last author,　Corresponding 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

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Scopus

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

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

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

CiNii Books

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

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

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

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

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

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：Japanese  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese  

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Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

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

Language：Japanese  

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

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

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

Language：Japanese

Language：Japanese

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Language：Japanese

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Language：Japanese

Language：Japanese

Publisher：Electronics and Communications in Japan  

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

Scopus

Language：English   Publishing type：Rapid communication, short report, research note, etc. (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

Web of Science

Event date： 2021.12

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