研究者詳細 - 瀨部　昇

論文 - 瀨部　昇

分割表示129 件中 21 - 40 件目／全件表示 >>

Reduction of steady-state error for a ramp input in type 1 servo systems 査読有り国際誌

Honoka Shimatate, Kana Shikada, Noboru Sebe

2022 61st Annual Conference of the Society of Instrument and Control Engineers of Japan, SICE 2022 924 - 929 2022年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Japan Kumamoto 2022年09月06日 - 2022年09月06日

This paper considers the reduction of steady-state error for ramp inputs in type 1 servo systems. It is well-known that type 2 servo systems track both step and ramp inputs. However, their transient responses for step inputs are oscillatory. On the other hand, in some applications, type 1 servo systems are required to track, but not exactly track, ramp inputs. For such systems, the characteristics between types 1 and 2 servo systems are desired. For such a problem, this paper proposes a weight function used for H∞ control theory in the sensitivity reduction problem. The proposed weight function reduces the gain of the sensitivity function in the low-frequency range. This allows small steady-state error for ramp inputs and makes the characteristics of the designed type 1 servo systems closer to type 2 servo systems. The effectiveness of the proposed method is demonstrated through numerical examples.

DOI： 10.23919/SICE56594.2022.9905769

DOI： 10.23919/SICE56594.2022.9905769

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Projection onto the Set of Rank-Constrained Structured Matrices for Reduced-Order Controller Design 査読有り国際誌

Nagahara M., Iwai Y., Sebe N.

Algorithms 15 ( 9 ) 2022年09月

記述言語：英語掲載種別：研究論文（学術雑誌）

In this paper, we propose an efficient numerical computation method of reduced-order controller design for linear time-invariant systems. The design problem is described by linear matrix inequalities (LMIs) with a rank constraint on a structured matrix, due to which the problem is non-convex. Instead of the heuristic method that approximates the matrix rank by the nuclear norm, we propose a numerical projection onto the rank-constrained set based on the alternating direction method of multipliers (ADMM). Then the controller is obtained by alternating projection between the rank-constrained set and the LMI set. We show the effectiveness of the proposed method compared with existing heuristic methods, by using 95 benchmark models from the COMPL (Formula presented.) ib library.

DOI： 10.3390/a15090322

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Design of Observer-Structured H<inf>∞</inf> Flight Controllers Converted from Unstructured Conventional H<inf>∞</inf> Flight Controllers 査読有り国際誌

Masayuki Sato, Noboru Sebe

IFAC-PapersOnLine (ROCOND2022) 55 ( 25 ) 19 - 24 2022年08月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Japan Kyoto (online) 2022年08月30日 - 2022年09月02日

We address the conversion problem from a priori designed unstructured Linear Time-Invariant (LTI) controllers to observer-structured LTI controllers, whose structure is similar to but is not exactly the same as the so-called “Luenberger observer-based controllers”, for Linear Parameter-Varying (LPV) or LTI Parameter-Dependent (LTIPD) plant systems. For this problem, we propose a method by designing appropriate state transformation matrices which minimize the errors between plant systems' states and transformed controllers' states for external inputs via parametrically multi-affine Linear Matrix Inequality (LMI) conditions. The proposed method embeds existing LTI controllers with the ability of observers while their control performance is unchanged. We introduce a numerical example and illustrate the usefulness of our method by embedding observer property to an a priori designed H∞ flight controller.

DOI： 10.1016/j.ifacol.2022.09.317

DOI： 10.1016/j.ifacol.2022.09.317

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Selection of the estimation model for robust observer-based controller against plant uncertainties 査読有り国際誌

Kana Shikada, Noboru Sebe, Masayuki Sato

IFAC-PapersOnLine (ROCOND2022) 55 ( 25 ) 193 - 198 2022年08月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Japan Kyoto (online) 2022年08月30日 - 2022年09月02日

This paper is concerned with the design of robust controllers with observers. In general, the nominal model is selected as the state-space model for the observer to estimate the states even if the plant has uncertainties. However, the properness of this strategy is ambiguous. This paper evaluates the properness of selecting the nominal model for state estimation of the plant with uncertainties. Sato (2018a) proposed a new type of controller so-called observer-structured controller. The controller introduces additional freedom for selecting the state-space model used for the state estimation. With this type of controller, this paper demonstrates that the adequate selection of estimation model improves the closed-loop control performance through numerical examples.

DOI： 10.1016/j.ifacol.2022.09.346

DOI： 10.1016/j.ifacol.2022.09.346

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Conversion From Unstructured LTI Controllers to Observer-Structured Ones for LPV Systems 査読有り国際誌

Masayuki Sato, Noboru Sebe

Frontiers in Control Engineering 3 2022年08月

Augmented switching L<inf>2</inf> gain for evaluating the smoothness of transient responses after a system switch 査読有り

Suyama K., Sebe N.

2022 European Control Conference, ECC 2022 1097 - 1102 2022年07月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

United Kingdom London 2022年07月12日 - 2022年07月15日

In this paper, we focus on the smoothness of transient responses after a system switch to propose a new augmented switching L2 gain including the evaluation of their differential. Moreover, we apply it to the initial state design of a newly-activated controller at a controller switch to establish its potential practicality as a design index.

DOI： 10.23919/ECC55457.2022.9838245

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L<inf>2+</inf> Induced Norm Analysis of Continuous-Time LTI Systems Using Positive Filters and Copositive Programming 査読有り国際誌

Ebihara Y., Motooka H., Waki H., Sebe N., Magron V., Peaucelle D., Tarbouriech S.

2022 European Control Conference, ECC 2022 1385 - 1390 2022年07月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

United Kingdom London 2022年07月12日 - 2022年07月15日

This paper is concerned with the analysis of the L2 induced norm of continuous-time LTI systems where the input signals are restricted to be nonnegative. This induced norm is referred to as the L2+ induced norm in this paper. It has been shown very recently that the L2+ induced norm is particularly useful for the stability analysis of nonlinear feedback systems constructed from linear systems and static nonlinearities where the nonlinear elements only provide nonnegative signals. For the upper bound computation of the L2+ induced norm, an approach with copositive programming has also been proposed. It is nonetheless true that this approach becomes effective only for multi-input systems, and for single-input systems this approach does not bring any improvement over the trivial upper bound, the standard L2 norm. To overcome this difficulty, we newly introduce positive filters to increase the number of positive signals. This enables us to enlarge the size of the copositive multipliers so that we can obtain better (smaller) upper bounds with copositive programming. Keywords: nonnegative signal, L2+ induced norm, positive filter, copositive programming

DOI： 10.23919/ECC55457.2022.9838085

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線形時不変パラメータ依存プラントに対する既設計の非構造化制御器からオブザーバ構造型制御器への変換査読有り

佐藤昌之, 瀬部昇

計測自動制御学会論文集 ( 公益社団法人計測自動制御学会 ) 58 ( 5 ) 255 - 261 2022年05月

記述言語：日本語掲載種別：研究論文（学術雑誌）

<p>This paper considers the conversion problem from strictly proper non-structured Linear Time-Invariant (LTI) controllers, which are designed <i>a priori</i>, to strictly proper “observer-structured LTI controllers”, whose structure is similar to but not exactly the same as the so-called “Luenberger observer-based LTI controllers”, for LTI Parameter-Dependent (LTIPD) plant systems. We parametrize the state-space matrices of the observer-structured controllers with those of the non-structured controllers, one free matrix and a state transformation matrix, and propose a method to obtain the optimal state transformation matrix with respect to the convergence of non-zero initial plant state. We also clarify the relation between our method and an existing one for full-order controllers for LTI plant systems.</p>

DOI： 10.9746/sicetr.58.255

Development of Support Programs for Solving BMI Problems by Overbounding Approximation Method 査読有り国際誌

Jiulin Zhu, Noboru Sebe

2022 SICE International Symposium on Control Systems 9 - 15 7 pages 2022年03月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Japan Tokyo 2022年03月07日 - 2022年03月10日

A support program that implements the overbounding approximation method for MATLAB and YALMIP is developed. The overbounding approximation is one of the methods that provide sufficient LMI constraints for the given BMI constraints. With this method, one can obtain an approximate solution to the given BMI problem. However, it is not easy for ordinary users to implement the method to solve BMI problems. To overcome the difficulty, we provide a function that finds initial solutions for optimization and solves BMI problems automatically. This function enables users to obtain solutions for the BMI problem easily.

DOI： 10.23919/SICEISCS54350.2022.9754368

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周波数領域における拘束条件下での入力行列内のパラメータ推定査読有り

佐藤昌之, 瀬部昇

計測自動制御学会論文集 ( 計測自動制御学会 ) 58 ( 2 ) 100 - 104 2022年02月

Design of safe preventive maintenance procedure for control systems 査読有り国際誌

Suyama K., Sebe N.

Conference on Control and Fault-Tolerant Systems, SysTol 2021 37 - 43 2021年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

France St Raphael 2021年09月29日 - 2021年10月01日

By applying the initial state design using a state-dependent switching L2 gain to the safe maintenance procedure presented before, we improve the safety of transitions between operating states to bring the procedure to completion as a support technology for safe and partially-performed preventive maintenance of linear time-invariant control systems.

DOI： 10.1109/SysTol52990.2021.9595792

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A Dense Optical Flow Estimation Based on Dynamical System Approach under Intensity Variation Violating the Conservation Law 査読有り国際誌

Nakamura A., Sebe N., Enokida S., Nobuyama E.

2021 60th Annual Conference of the Society of Instrument and Control Engineers of Japan, SICE 2021 472 - 477 2021年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Japan Tokyo 2021年09月08日 - 2021年09月10日

Optical flow is a vector that represents the motion of objects in images. To estimate the optical flow, most of the optical flow estimation methods assume the intensity conservation law. The estimation methods based on a dynamical system approach [3], [4] also use the same assumption. Therefore, these methods might not be able to estimate correctly if the intensity conservation law is violated by various factors. A estimation model at a pixel considering the illumination change was proposed in [7] to improve the estimation accuracy in such situations. This paper proposes a new dense estimation model with the intensity correction quantity to overcome the estimation in the illumination change and the occlusion. Furthermore, this paper proposes to estimate the optical flow with the Kalman filter or the Kalman filter with the sparse constraint to correction quantity. Using the sparse constraint, the correction quantity becomes non-zero only near the flow boundaries. Accordingly, the improvement of estimation accuracy can expect. The effectiveness of the proposed models is demonstrated through numerical examples.

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Robust observer-based controller against plant uncertainties 査読有り国際誌

Shikada K., Sebe N., Sato M.

2021 60th Annual Conference of the Society of Instrument and Control Engineers of Japan, SICE 2021 1196 - 1201 2021年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Japan Tokyo 2021年09月08日 - 2021年09月10日

This paper concerns a method of constructing observers for the plant with uncertainties. In a conventional design, the nominal system matrix is chosen as the system matrix of the observer for the system with/without the uncertainties. However, the rationale of this strategy is ambiguous. This paper investigates the degree of freedom in selecting the system matrix of the observer. The observer-structured controllers designed with freedom of the selection are evaluated in the H2 control and estimation performances.

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Safety Design of Control Systems According to International Standards 査読有り国際誌

Koichi Suyama, Noboru Sebe

Proceedings of 2021 European Control Conferenc 1305 - 1310 2021年07月

Reduction of SISO H-infinity output feedback control problem 査読有り国際誌

Waki H., Ebihara Y., Sebe N.

Linear Algebra and Its Applications 610 ( 1 ) 321 - 378 2021年02月

記述言語：英語掲載種別：研究論文（学術雑誌）

We consider the linear matrix inequality (LMI) problem of H output feedback control problem for a generalized plant whose control input, measured output, disturbance input, and controlled output are scalar. We provide an explicit form of the optimal value. This form is the unification of some results in the literature of H performance limitation analysis. To obtain the form of the optimal value, we focus on the non-uniqueness of perpendicular matrices, which appear in the LMI problem. We use the null vectors of invariant zeros associated with the dynamical system for the expression of the perpendicular matrices. This expression enables us to reduce and simplify the LMI problem. Our approach uses some well-known fundamental tools, e.g., the Schur complement, Lyapunov equation, Sylvester equation, and matrix completion. We use these techniques for the simplification of the LMI problem. Also, we investigate the structure of dual feasible solutions and reduce the size of the dual. This reduction is called a facial reduction in the literature of convex optimization. ∞ ∞

DOI： 10.1016/j.laa.2020.09.034

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On Gain-Scheduled State-Feedback Controller Synthesis with Quadratic Stability Condition 査読有り国際誌

Ebihara Y., Sebe N., Waki H.

Proceedings of 59th IEEE Conference on Decision and Control 4 ( 3 ) 2020年12月

A New Optical Flow Estimation Based on Dynamical System Approach with Intensity Variation Violating the Conservation Law 査読有り国際誌

Nakamura A., Sebe N., Enokida S., Nobuyama E.

2020 59th Annual Conference of the Society of Instrument and Control Engineers of Japan, SICE 2020 967 - 972 2020年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Thailand (online) Chiang Mai 2020年09月23日 - 2020年09月26日

Optical flow is a vector that represents the motion of objects in images. The dynamical system approach to optical flow estimation [3] was proposed as one of the optical flow estimation methods. Most of the optical flow estimation methods are based on the intensity conservation law. Therefore, these estimation methods might not be able to estimate correctly if the intensity conservation law is violated by various factors. This paper proposes a new estimation model for images in which the image intensity is not maintained after moving objects in images. The proposed method can estimate not only the optical flow and its spatial gradients but also the intensity variation and its spatial gradients that do not follow the intensity conservation law. In addition, this paper focuses on the possibility of the optical flow estimation from the perspective of the observability. The effectiveness of the proposed model is demonstrated through numerical examples.

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Robust fault-tolerant servo system against sensor failure and plant uncertainties 査読有り国際誌

Shikada K., Sebe N., Suyama K., Indriawati K.

2020 59th Annual Conference of the Society of Instrument and Control Engineers of Japan, SICE 2020 1886 - 1891 2020年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Thailand (online) Chiang Mai 2020年09月23日 - 2020年09月26日

This paper concerns with a design of robust fault-tolerant servo systems against sensor failures and plant uncertainties. The method already exists which estimates sensor failures with disturbance observer, and, constitutes a fault-tolerant control system. In this method, generally the optimal regulator theory is used to design a controller. However, this approach is not easy to consider the robustness against plant uncertainties. In this paper, a method for designing a robust fault-tolerant controller is proposed. This method enables us to consider the robustness by applying H∞ control theory. The effectiveness of the proposed design procedure is demonstrated by a numerical example.

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85096358023&origin=inward

Improvement of Convergence of the Overbounding Approximation Method for BMI problems by Regularization Term 査読有り国際誌

Azumi K., Sebe N.

2020 59th Annual Conference of the Society of Instrument and Control Engineers of Japan, SICE 2020 1880 - 1885 2020年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Thailand (online) Chiang Mai 2020年09月23日 - 2020年09月26日

This paper concerns with the regularization term for the overbounding approximation method. The overbounding approximation is one of the methods for solving bilinear matrix inequality (BMI) problems, but the overbounding approximation has problems about its convergence. This paper proposed a new weight parameters of the regularization terms to improve the convergence.

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A safety assessment framework of control systems according to international standards 査読有り国際誌

Suyama K., Sebe N.

Asian Journal of Control 22 ( 5 ) 1741 - 1754 2020年09月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019 Chinese Automatic Control Society and John Wiley & Sons Australia, Ltd In this paper, we propose an assessment framework for the safety function implemented in a controller according to international standards on safety. Such a function can prevent events where physical values in a control system deviate from the normal operating range, to the fullest extent possible. Therefore, it can decrease the frequency of demand occurrences on externally implemented safety-related systems and supplement them in risk reduction required by the international standards on safety, such as IEC 61508. In the proposed framework, by evaluating the possibility that the deviations occur because of the true effects of a failure/restoration by using the switching L2 gain for analyzing the fluctuations in transient responses after an unpredictable system switch, we can obtain the demand frequency as an assessment result.

DOI： 10.1002/asjc.2131

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