• Title, Summary, Keyword: linear time-varying system

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Wavelet network approximation and coefficient learning of linear-time-varying system (시변 선형 시스템의 웨이브렛망 근사화와 가중치의 학습)

  • 이영석;김동옥;서보혁
    • 제어로봇시스템학회:학술대회논문집
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    • pp.728-731
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    • 1997
  • This paper discusses approximation modelling of discrete-time linear time-varying system(LTVS). The wavelet transform is considered as a tool for representing and approximating a LTVS. The joint time-frequency properties of wave analysis are appropriate for describing the LTVS. Simulation results is included to illustrate the potential application of the technique.

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RBF Network Based QFT Parameter-Scheduling Control Design for Linear Time-Varying Systems and Its Application to a Missile Control System (시변시스템을 위한 RBF 신경망 기반의 QFT 파라미터계획 제어기법과 alt일 제어시스템에의 적용)

  • 임기홍;최재원
    • 제어로봇시스템학회:학술대회논문집
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    • pp.199-199
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    • 2000
  • Most of linear time-varying(LTV) systems except special cases have no general solution for the dynamic equations. Thus, it is difficult to design time-varying controllers in analytic ways, and other control design approaches such as robust control have been applied to control design for uncertain LTI systems which are the approximation of LTV systems have been generally used instead. A robust control method such as quantitative feedback theory(QFT) has an advantage of guaranteeing the stability and the performance specification against plant parameter uncertainties in frozen time sense. However, if these methods are applied to the approximated linear time-invariant(LTI) plants which have large uncertainty, the designed control will be constructed in complicated forms and usually not suitable for fast dynamic performance. In this paper, as a method to enhance the fast dynamic performance, the approximated uncertainty of time-varying parameters are reduced by the proposed QFT parameter-scheduling control design based on radial basis function (RBF) networks for LTV systems with bounded time-varying parameters.

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Tracking control of variable stiffness hysteretic-systems using linear-parameter-varying gain-scheduled controller

  • Pasala, D.T.R.;Nagarajaiah, S.;Grigoriadis, K.M.
    • Smart Structures and Systems
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    • v.9 no.4
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    • pp.373-392
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    • 2012
  • Tracking control of systems with variable stiffness hysteresis using a gain-scheduled (GS) controller is developed in this paper. Variable stiffness hysteretic system is represented as quasi linear parameter dependent system with known bounds on parameters. Assuming that the parameters can be measured or estimated in real-time, a GS controller that ensures the performance and the stability of the closed-loop system over the entire range of parameter variation is designed. The proposed method is implemented on a spring-mass system which consists of a semi-active independently variable stiffness (SAIVS) device that exhibits hysteresis and precisely controllable stiffness change in real-time. The SAIVS system with variable stiffness hysteresis is represented as quasi linear parameter varying (LPV) system with two parameters: linear time-varying stiffness (parameter with slow variation rate) and stiffness of the friction-hysteresis (parameter with high variation rate). The proposed LPV-GS controller can accommodate both slow and fast varying parameter, which was not possible with the controllers proposed in the prior studies. Effectiveness of the proposed controller is demonstrated by comparing the results with a fixed robust $\mathcal{H}_{\infty}$ controller that assumes the parameter variation as an uncertainty. Superior performance of the LPV-GS over the robust $\mathcal{H}_{\infty}$ controller is demonstrated for varying stiffness hysteresis of SAIVS device and for different ranges of tracking displacements. The LPV-GS controller is capable of adapting to any parameter changes whereas the $\mathcal{H}_{\infty}$ controller is effective only when the system parameters are in the vicinity of the nominal plant parameters for which the controller is designed. The robust $\mathcal{H}_{\infty}$ controller becomes unstable under large parameter variations but the LPV-GS will ensure stability and guarantee the desired closed-loop performance.

The Controller Design for a Class of Time-Varying Linear System via I/O Transformation (입출력 변환을 이용한 선형 시변 시스템의 제어기 설계)

  • Cho, Do-Hyeoun;Lee, Sang-Hun;Lee, Jong-Yong
    • 전자공학회논문지 IE
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    • v.43 no.3
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    • pp.28-33
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    • 2006
  • In this paper, we consider the input-output(I/O) transformation for the time-varying linear system and get the time-invarying linear system. And we present the necessary sufficient condition for the I/O transformation. The transformed system represent the system with the multiple integral. We verify the proposal algorithm via the example and examine.

The Interpreter Controllability and Observability for a Class of Time-varying Linear System via I/S and I/O Transformation (입력-상태, 입력-출력 변환을 이용한 선형 시변 시스템의 가제어성, 가관측성 해석)

  • Won, Young-Jin;Lee, Sang-Hun;Lee, Jong-Yong
    • 전자공학회논문지 IE
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    • v.44 no.3
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    • pp.51-55
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    • 2007
  • In this paper, we consider the controllability and observability for the time-varying linear system using the input-state(I/O), input-output(I/O) transformation and get the time-invarying linear system. The transformed system represent the system with the multiple integral. We verify the proposal algorithm via the example and examine.

Guaranteed Cost Control for Discrete-time Linear Uncertain Systems with Time-varying Delay (시변 시간지연을 가지는 이산 선형 불확실성 시스템에 대한 보장 비용 제어)

  • Kim, Ki-Tae;Cho, Sang-Hyun;Lee, Sang-Kyung;Park, Hong-Bae
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.39 no.6
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    • pp.20-26
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    • 2002
  • This paper deals with the guaranteed cost control problems for a class of discrete-time linear uncertain systems with time-varying delay. The uncertain systems under consideration depend on time-varying norm-bounded parameter uncertainties. We address the existence condition and the design method of the memoryless state feedback control law such that the closed loop system not only is quadratically stable but also guarantees an adequate level of performance for all admissible uncertainties. Through some changes of variables and Schur complement, It is shown that the sufficient condition can be rewritten as an LMI(linear matrix inequality) form in terms of all variables.

Design of Autonomous Cruise Controller with Linear Time Varying Model

  • Chang, Hyuk-Jun;Yoon, Tae Kyun;Lee, Hwi Chan;Yoon, Myung Joon;Moon, Chanwoo;Ahn, Hyun-Sik
    • Journal of Electrical Engineering and Technology
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    • v.10 no.5
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    • pp.2162-2169
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    • 2015
  • Cruise control is a technology for automatically maintaining a steady speed of vehicle as set by the driver via controlling throttle valve and brake of vehicle. In this paper we investigate cruise controller design method with consideration for distance to vehicle ahead. We employ linear time varying (LTV) model to describe longitudinal vehicle dynamic motion. With this LTV system we approximately model the nonlinear dynamics of vehicle speed by frequent update of the system parameters. In addition we reformulate the LTV system by transforming distance to leading vehicle into variation of system parameters of the model. Note that in conventional control problem formulation this distance is considered as disturbance which should be rejected. Consequently a controller can be designed by pole placement at each instance of parameter update, based on the linear model with the present system parameters. The validity of this design method is examined by simulation study.

Design of Repetitive Control System for Linear Systems with Time-Varying Uncertainties (시변 불확실성을 가지는 선형 시스템을 위한 반복 제어 시스템의 설계)

  • Chung Myung Jin;Doh Tae-Yong
    • Journal of Institute of Control, Robotics and Systems
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    • v.11 no.1
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    • pp.13-18
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    • 2005
  • This paper considers a design problem of the repetitive control system for linear systems with time-varying norm bounded uncertainties. Using the Lyapunov functional for time-delay systems, a sufficient condition ensuring robust stability of the repetitive control system is derived in terms of an algebraic Riccati inequality (ARI) or a linear matrix inequality (LMI). Based on the derived condition, we show that the repetitive controller design problem can be reformulated as an optimization problem with an LMI constraint on the free parameter.

STABILITY AND CONSTRAINED CONTROLLABILITY OF LINEAR CONTROL SYSTEMS IN BANACH SPACES

  • Phat, Vu-Ngoc;Park, Jong-Yeoul;Jung, Il-Hyo
    • Journal of the Korean Mathematical Society
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    • v.37 no.4
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    • pp.593-611
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    • 2000
  • For linear time-varying control systems with constrained control described by both differential and discrete-time equations in Banach spaces was give necessary and sufficient conditions for exact global null-controllability. We then show that for such systems, complete stabilizability implies exact null-controllability.

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QFT Parameter-Scheduling Control Design for Linear Time- varying Systems Based on RBF Networks

  • Park, Jae-Weon;Yoo, Wan-Suk;Lee, Suk;Im, Ki-Hong;Park, Jin-Young
    • Journal of Mechanical Science and Technology
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    • v.17 no.4
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    • pp.484-491
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    • 2003
  • For most of linear time-varying (LTV) systems, it is difficult to design time-varying controllers in analytic way. Accordingly, by approximating LTV systems as uncertain linear time-invariant, control design approaches such as robust control have been applied to the resulting uncertain LTI systems. In particular, a robust control method such as quantitative feedback theory (QFT) has an advantage of guaranteeing the frozen-time stability and the performance specification against plant parameter uncertainties. However, if these methods are applied to the approximated linear. time-invariant (LTI) plants with large uncertainty, the resulting control law becomes complicated and also may not become ineffective with faster dynamic behavior. In this paper, as a method to enhance the fast dynamic performance of LTV systems with bounded time-varying parameters, the approximated uncertainty of time-varying parameters are reduced by the proposed QFT parameter-scheduling control design based on radial basis function (RBF) networks.