Country：Japan

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

DOI： 10.1299/mej.21-00095

Web of Science

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

DOI： 10.1109/ACCESS.2021.3076186

Web of Science

Authorship：Lead author,　Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：計測自動制御学会  

DOI： 10.9746/sicetr.57.92

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

DOI： 10.1109/LSENS.2020.2999186

Web of Science

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

DOI： 10.3390/en13061325

Web of Science

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

DOI： 10.1109/TAC.2019.2912452

Web of Science

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

DOI： 10.1299/mej.20-00276

Web of Science

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

DOI： 10.1016/j.ifacol.2018.11.104

Web of Science

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

DOI： 10.9746/jcmsi.11.154

Language：English  

DOI： 10.1109/ICUAS.2018.8453395

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

DOI： 10.1016/j.ifacol.2018.12.083

Web of Science

Language：English  

DOI： 10.1109/CCTA.2017.8062478

Web of Science

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

DOI： 10.1109/TAC.2016.2564958

Web of Science

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

This paper proposes a predictor-based state feedback controller for multi-input linear time-invariant (LTI) systems with different time delays in each individual input channel. The controller is derived based on the backstepping method. Since the conventional backstepping transformation is not applicable to the systems due to the differences among delays, a modified transformation is introduced. This transformation enables us to design an exponentially stabilizing controller under which the plant behaves as if the delays were absent after a finite time interval. As a dual of the controller design, we also present the observer design for multi-output LTI systems with distinct sensor delays. A numerical simulation confirms the performance of the proposed controller.

DOI： 10.1016/j.automatica.2016.04.047

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

DOI： 10.1109/TAC.2015.2495622

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

DOI： 10.1002/rnc.3307

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

DOI： 10.1080/01691864.2015.1090333

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

This paper is concerned with the observer design for one-dimensional linear parabolic partial differential equations whose output is a weighted spatial average of the state over the entire spatial domain. We focus on the backstepping approach, which provides a systematic procedure to design an observer gain for systems with boundary measurement. If the output is not a boundary value of the state, the backstepping approach is not directly applicable to obtaining an observer gain that stabilizes the error dynamics. Therefore, we attempt to convert the error system into another system to which backstepping is applicable. The conversion is successfully achieved for a class of weighting functions, and the resultant observer realizes exponential convergence of the estimation error with an arbitrary decay rate in terms of the L2 norm. In addition, an explicit expression of the observer gain is available in a special case. The effectiveness of the proposed observer is also confirmed by numerical simulations.

DOI： 10.1016/j.automatica.2014.12.019

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

Large-scale dynamical systems often consist of a number of subsystems that are interconnected according to a hierarchical multi-scale network. This paper introduces a hierarchical control scheme as an efficient strategy to handle such systems and proposes a method for designing a hierarchical linear quadratic optimal regulator. The proposed framework employs an algebraic approach. We first characterize a hierarchy of systems as an algebra based on semigroups, the Kronecker product, and the linear combination. This allows us to prove that the stabilizing solution of the Riccati equation inherits a hierarchy if system matrices and weights in the cost function belong to the corresponding common algebra that characterizes the hierarchy. A couple of classes of systems that can be treated by our algebraic framework are also provided in the paper. We will see that the derived result gives a unified insight into several related previous works.

DOI： 10.9746/sicetr.49.1154

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

This paper considers a boundary stabilization problem of systems described by boundary coupled two one-dimensional parabolic partial differential equations based on the backstepping method. Unlike the conventional backstepping framework, we propose a state transformation that contains the state of the unforced subsystem partially. It is proved that this transformation is well-defined and converts the original system into an exponentially stable system together with an associated state feedback control law under a condition that ensures the stability of the unforced subsystem. The original system with this control law inherits the stability of the transfomed one. The effectiveness of the obtained control law is demonstrated numerically.

DOI： 10.5687/iscie.26.277

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

This paper considers a boundary stabilization problem of systems described by boundary coupled two one-dimensional parabolic partial differential equations based on the backstepping method. Unlike the conventional backstepping framework, we propose a state transformation that contains the state of the unforced subsystem partially. It is proved that this transformation is well-defined and converts the original system into an exponentially stable system together with an associated state feedback control law under a condition that ensures the stability of the unforced subsystem. The original system with this control law inherits the stability of the transfomed one. The effectiveness of the obtained control law is demonstrated numerically.

DOI： 10.1016/j.sysconle.2011.11.008

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

In this paper a computational algorithm for nonlinear balanced realization and model reduction based on Taylor series expansion is proposed. This algorithm requires recursive computations with respect to the order of the Taylor series in which we need to solve linear equations with unknown parameters in each step. Furthermore, the proposed method is applied to a double pendulum system. Some numerical simulations demonstrate the effectiveness of the proposed algorithm.

DOI： 10.1016/j.sysconle.2007.08.015

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

This paper proposes a weighted balanced realization and model order reduction for nonlinear systems. This is an extension of a nonlinear balanced realization, which is based on singular value analysis of the nonlinear Hankel operator, to include input and output weights. The proposed method is a natural nonlinear extension of weighted balanced realization for linear systems. Furthermore, it is proved that a reduced order model derived by the proposed procedure is also stable if the original model is so. Finally, the effectiveness of the method is shown by a numerical simulation.

DOI： 10.9746/ve.sicetr1965.44.44

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

DOI： 10.5687/iscie.20.358

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

Effective location of plasma actuators for a flow separation control over a NACA 0012 airfoil is investigated by computational simulations. Single plasma actuator is located at 5%, 10% or 20% chord from the leading edge. The results indicate that the actuator located near the separation has a better capability to control flow separations. Separation is once avoided when a single actuator is located near the separation, another separation occurs from the trailing edge. This motivates to use multiple actuators and the separations are carried out for two actuators. The result shows the possibi...

DOI： 10.1299/kikaib.73.663

Event date： 2024.3

Language：Japanese   Presentation type：Public lecture, seminar, tutorial, course, or other speech  

Venue：Higashi-Hiroshima   Country：Japan  

Event date： 2023.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Sendai   Country：Japan  

DOI： 10.11511/jacc.66.0_1152

Other Link： https://doi.org/10.11511/jacc.66.0_1152

Event date： 2023.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Sendai   Country：Japan  

DOI： 10.11511/jacc.66.0_28

Other Link： https://doi.org/10.11511/jacc.66.0_28

Event date： 2023.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Sendai   Country：Japan  

DOI： 10.11511/jacc.66.0_391

Other Link： https://doi.org/10.11511/jacc.66.0_391

Event date： 2023.7

Language：English   Presentation type：Oral presentation (general)  

Venue：Yokohama   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Kusatsu, Shiga   Country：Japan  

Event date： 2022.12

Language：English   Presentation type：Oral presentation (general)  

Venue：Cancún   Country：Mexico  

DOI： 10.1109/CDC51059.2022.9992680

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Utsunomiya, Tochigi   Country：Japan  

DOI： 10.11511/jacc.65.0_1627

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Utsunomiya, Tochigi   Country：Japan  

DOI： 10.11511/jacc.65.0_1237

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Utsunomiya, Tochigi   Country：Japan  

DOI： 10.11511/jacc.65.0_1234

Event date： 2022.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Kumamoto   Country：Japan  

DOI： 10.23919/SICE56594.2022.9905801

Event date： 2022.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Atlanta, GA   Country：United States  

DOI： 10.23919/ACC53348.2022.9867714

Event date： 2022.5

Language：Japanese   Presentation type：Public lecture, seminar, tutorial, course, or other speech  

Venue：東京（ハイブリッド）   Country：Japan  

Event date： 2022.5

Language：English   Presentation type：Oral presentation (general)  

Venue： Jeju Island (hybrid)   Country：Korea, Republic of  

DOI： 10.23919/ASCC56756.2022.9828149

Event date： 2022.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2022.1

Language：English   Presentation type：Oral presentation (general)  

Venue：San Diego, CA & Online   Country：United States  

DOI： https://doi.org/10.2514/6.2022-1068

Event date： 2021.12

Language：Japanese   Presentation type：Public lecture, seminar, tutorial, course, or other speech  

Venue：オンライン   Country：Japan  

Event date： 2021.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.9

Language：English   Presentation type：Public lecture, seminar, tutorial, course, or other speech  

Venue：Online   Country：Japan  

Event date： 2021.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.3

Language：Japanese   Presentation type：Poster presentation  

Venue：オンライン   Country：Japan  

Event date： 2021.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.3

Language：Japanese   Presentation type：Poster presentation  

Venue：オンライン   Country：Japan  

Event date： 2021.1

Language：Japanese   Presentation type：Public lecture, seminar, tutorial, course, or other speech  

Venue：オンライン  

Event date： 2020.12

Language：Japanese   Presentation type：Poster presentation  

Venue：オンライン   Country：Japan  

Event date： 2020.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Online  

DOI： 10.11511/jacc.63.0_677

Event date： 2020.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Online  

DOI： 10.11511/jacc.63.0_955

Event date： 2020.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Online  

DOI： 10.11511/jacc.63.0_681

Event date： 2020.11

Language：Japanese   Presentation type：Poster presentation  

Venue：オンライン  

Event date： 2020.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Online   Country：Japan  

Event date： 2020.10

Language：English   Presentation type：Oral presentation (general)  

Venue：Online  

Event date： 2020.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Online  

DOI： 10.23919/SICE48898.2020.9240325

Event date： 2020.7

Language：English   Presentation type：Oral presentation (general)  

Venue：Online   Country：Germany  

DOI： 10.1016/j.ifacol.2020.12.1538

Event date： 2020.7

Language：English   Presentation type：Oral presentation (general)  

Event date： 2020.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Web 開催   Country：Japan  

Event date： 2020.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2020.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：新型コロナウイルス感染症拡大防止のため中止（予稿集は発行）   Country：Japan  

Event date： 2020.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：新型コロナウイルス感染症拡大防止のため中止（予稿集のみ発行）   Country：Japan  

Event date： 2019.11

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.11

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.11

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.11

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.11

Language：Japanese   Presentation type：Symposium, workshop panel (nominated)  

Country：Japan  

Event date： 2019.11

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.11

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.9

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2018.11

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

DOI： 10.11511/jacc.61.0_59

Event date： 2018.11

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

DOI： 10.11511/jacc.61.0_1304

Event date： 2018.10

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2018.9

Language：Japanese   Presentation type：Oral presentation (invited, special)  

Venue：伊豆山研修センター（静岡県熱海市）   Country：Japan  

Event date： 2018.7

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2018.5

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2017.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Kanazawa University   Country：Japan  

Event date： 2017.8

Language：English   Presentation type：Oral presentation (general)  

Venue：The Mauna Lani Bay Hotel and Bungalows, Kohala Coast, Hawai'i   Country：United States  

Event date： 2015.7

Language：English   Presentation type：Oral presentation (general)  

Country：United States  

In this paper, we propose a predictor-based state feedback controller for multi-input linear time-invariant systems with different time delays in each individual input channel. The controller is designed based on the backstepping method. Since the conventional backstepping transformation is not applicable to the systems due to the differences among delays, a modified transformation is introduced. This transformation enables us to design an exponentially stabilizing controller under which the plant behaves as if the delay were absent after a finite time interval. In addition, an explicit Lyapunov functional is constructed. The performance of the controller is demonstrated by a numerical simulation.

Event date： 2015.7

Language：English   Presentation type：Oral presentation (general)  

Country：United States  

In this paper, we generalize the previous results of multivariable extremum seeking by assuming output delays not considered before in the control system. The phase compensation of the dither signals and the inclusion of an averaging-based predictor in the closed-loop feedback allow to obtain exponential convergence results to a small neighborhood of the optimal point, even in the presence of delays. The stability analysis is carried out using backstepping transformation and averaging in infinite dimensions. The proposed approach also removes the dependence of the convergence rate on the unknown Hessian of the nonlinear map to be optimized, being user-assignable as in Newton-based extremum seeking results. The control performance is evaluated by numerical simulations.

Event date： 2015.6

Language：English   Presentation type：Oral presentation (general)  

Country：Malaysia  

This paper proposes an indirect method for designing a Luenberger-type state observer for systems described by boundary-coupled two parabolic partial differential equations. In particular, we concentrate on the case where outputs are spatial averages of the state variables. The proposed method consists of two steps. We first introduce a state transformation that converts the system into another system with boundary measurement. Then, the backstepping approach can provide a state observer for the converted system. An estimate of the original state variables is constructed through the inverse transformation. The performance of the proposed observer is confirmed by a numerical simulation.

Event date： 2014.12

Language：English   Presentation type：Oral presentation (general)  

Country：United States  

This paper considers a boundary control problem of parabolic partial differential equations (PDEs) with an integral of the state variable over the whole spatial domain. To handle this non-strict feedback term, we use a Fredholm-type state transformation that involves two integral terms with kernels defined on the lower and the upper triangular domains. It is shown that the transformation converts the original system with an associated state feedback law into an exponentially stable target system, if the kernels are solutions to a boundary value problem of coupled second-order hyperbolic PDEs. Moreover, the upper kernel is separable if a coefficient of the original system is characterized by a certain parameterized ordinary integro-differential equation. Our approach also provides an explicit feedback gain in a special case. The effectiveness of the proposed controller is confirmed by numerical simulation.

Event date： 2014.9

Language：English   Presentation type：Oral presentation (general)  

Country：France  

This paper considers a formation control problem of two-wheeled vehicles. We first design a base controller based on the structured linear quadratic optimal regulator. The resulting optimal control gain is a lower triangular matrix; thus, agents communicate with each other in a top-down manner. However, vehicles may collide with each other under this control law since it is linear. To avoid collision of vehicles, we design a potential function by deforming the quadratic form of the stabilizing solution of the Riccati equation. The gradient of the potential function gives a control law that guarantees collision avoidance. The control law coincides with the optimal control law if vehicles are far from each other. The effectiveness of the proposed controller is confirmed by numerical simulation.

Event date： 2013.12

Language：English   Presentation type：Oral presentation (general)  

Country：Italy  

In this paper, a state feedback control law is proposed for boundary coupled two different one-dimensional parabolic partial differential equations (PDEs). The control input is assumed to act only at a boundary of one side. The feedback law is designed based on the backstepping method. As a novelty of this paper, a state transformation involving a `discontinuous' integral kernel is introduced in order to handle the difference of diffusion coefficients. This enables us to develop a well-posed backstepping framework for cascades of parabolic PDEs and an exponentially stabilizing controller is derived. The performance of the proposed controller is also validated by numerical simulation.

Event date： 2013.6

Language：English   Presentation type：Oral presentation (general)  

Country：Turkey  

This paper considers a linear quadratic optimal hierarchical control problem for large-scale dynamical systems modeled by an interconnected system under multi-scale information exchange networks. We first propose an algebraic characterization of hierarchies by using semigroups the Kronecker product. The multiplication rule of the Kronecker product quite fits to the property of semigroups. As a result, a condition under which the stabilizing solution of the Riccati equation inherits the hierarchy is obtained with the aid of the previous result. Furthermore, the proposed framework makes it possible to understand several previous results on decentralized optimal control from a unified viewpoint.

Event date： 2012.6

Language：English   Presentation type：Oral presentation (general)  

Country：Canada  

The backstepping method is a systematic design tool for boundary control of various types of partial differential equations (PDEs). There has been no attempt to apply it to PDEs whose input is not at the boundary. In this paper, we consider a problem of feedback stabilization of 1-dimensional parabolic (unstable) PDEs with internal actuation based on the backstepping method. Since such a PDE can not be converted to a stable PDE by state feedback and the state transformation used in backstepping, an additional transformation is introduced. Under a certain condition, the newly proposed transformation moves the input from the interior of the domain to the boundary. This enables us to cancel the residual term that causes the open-loop instability by using the input. Furthermore, this transformation is continuously invertible. Therefore, a stabilizing state feedback for the original PDE is derived through the inverse transformation. The results are demonstrated by a numerical simulation.

Event date： 2011.8

Language：English   Presentation type：Oral presentation (general)  

Country：Italy  

This paper is concerned with designing a backstepping-based observer for a class of 1-dimensional parabolic distributed parameter systems whose output is a weighted spatial average of the state. We first show that an integral transformation converts the original system into another parabolic system with boundary observation if the weighting function satisfies a parameterized ordinary differential equation. Then the backstepping observer for the transformed system is available and an estimate of the original state is obtained through the inverse transformation. We also show that the estimation error exponentially converges to 0 in terms of the L2 norm with arbitrary decay rate. Furthermore, a closed-form expression of the observer is provided for systems described by linear reaction-diffusion equations.

Event date： 2010.9

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

In this paper, we investigate hierarchical multi-agent dynamical systems with low rank interconnection based on a new concept of eigen-interconnection. The eigenvector plays an important role in our framework. We first define the eigen-interconnection matrix for the rank one case. Then, we show eigenvalue distribution of a hierarchical interconnection with rank one eigen-interconnection matrix. The obtained eigenvalue distribution has explicit parameter dependency and the result allows us to place the eigenvalue selectively. Thus it gives useful knowledge to design hierarchical interconnection structure. This concept is naturally extended to the rank two case and a similar result for eigenvalue distribution is obtained. Those results completely include the previous researches as special cases. Furthermore, our characterization has a potential of straightforward extension to the higher rank cases. Finally, we show a numerical example where a hierarchical interconnection structure is designed based on our result.

Event date： 2009.8

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

In this paper, we propose a hierarchical modeling of the systems described by conservation laws. A conservation law on a hierarchically parted domain can be considered as a subsystem which interacts with neighbor elements through fluxes. Therefore, we regard the system as a networked system of each subsystem. The important idea is to weaken the interconnection in the sense of a rank. For detailed analysis of our method, we apply the proposed method to a diffusion equation. The hierarchical model is described by a non-circulant block Toeplitz matrix. Because the resulting system is symmetrically-networked system, we can show that the eigenvalues of the system consist of those of related uniform models. We also show that our method relaxes the stability condition of the fully discretized model. Finally we examine the performance of the hierarchical model by numerical simulations.

Event date： 2007.1

Language：English   Presentation type：Oral presentation (general)  

Country：United States  

Event date： 2006.7

Language：English   Presentation type：Oral presentation (general)  

Country：Belgium  

Event date： 2006.7

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

In this paper a weighted balanced realization and model reduction for nonlinear systems is proposed which is based on singular value analysis of nonlinear Hankel operators. In the proposed model reduction procedure, an important property, stability is preserved. A numerical ex- ample is also shown. This result is expected to be a basis for weighted model order reduction for nonlinear systems.

Event date： 2006.6

Language：English   Presentation type：Oral presentation (general)  

Country：United States  

In this paper a computational algorithm for nonlinear balanced realization and model reduction based on Taylor series expansion is proposed. This algorithm requires recursive computations with respect to the order of the Taylor series in which we need to solve linear equations with unknown parameters in each step. Furthermore, the proposed method is applied to a double pendulum system. Some numerical simulations demonstrate the effectiveness of the proposed algorithm.