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

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Eigenstructure Assignment for Linear Time-Varying Systems: a Differential Sylvester Equation Approach (미분 Sylvester 방정식을 이용한 선형 시변 시스템의 고유구조 지정기법)

  • 최재원;이호철
    • Journal of Institute of Control, Robotics and Systems
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    • v.5 no.7
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    • pp.777-786
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    • 1999
  • This work is concerned with the assignment of the desired eigenstructure for linear time-varying systems such as missiles, rockets, fighters, etc. Despite its well-known limitations, gain scheduling control appeared to be the focus of the research efforts. Scheduling of frozen-time, frozen-state controller for fast time-varying dynamics is known to be mathematically fallacious, and practically hazardous. Therefore, recent research efforts are being directed towards applying time-varying controllers. In this paper, ⅰ) we introduce a differential algebraic eigenvalue theory for linear time-varying systems, and ⅱ) we also propose an eigenstructure assignment scheme for linear time-varying systems via the differential Sylvester equation based upon the newly developed notions. The whole design procedure of the proposed eigenstructure assignment scheme is very systematic, and the scheme could be used to determine the stability of linear time-varying systems easily as well as provides a new horizon of designing controllers for the linear time-varying systems. The presented method is illustrated by a numerical example.

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Discrete-Time Sliding Mode Controller for Linear Time-Varying Systems with Disturbances

  • Park, Kang-Bak
    • Transactions on Control, Automation and Systems Engineering
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    • v.2 no.4
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    • pp.244-247
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    • 2000
  • In this paper, a discrete-time sliding mode controller for linear time-varying systems with disturbances is proposed. The proposed method guarantees the systems state is globally uniformly ultimately bounded(G.U.U.B) under the existence of time-varying disturbances.

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Robust Stability of Uncertain Discrete-Time Linear Systems with Time-Varying Delays (시변 시간 지연을 갖는 불확실한 이산 시간 선형 시스템의 견실 안정성)

  • Song, Seong-Ho;Park, Seop-Hyeong;Lee, Bong-Young
    • Journal of Institute of Control, Robotics and Systems
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    • v.5 no.6
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    • pp.641-646
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    • 1999
  • This paper deals with the robust stability of discrete-time linear systems with time- varying delays and norm-bounded uncertainties. In this paper, the magnitude of time-varying delays is assumed to be upper-bounded. The sufficient condition is presented in terms of linear matrix inequality. It is also shown that the robust stability of uncertain discrete-time linear systems with time-varying delays is related with the quadratic stability of uncertain discrete-time linear systems with constant time delay.

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The robust control for a linear time-varying system using state transformation (상태 변환을 이용한 선형 시변 시스템에 대한 강건한 제어)

  • Cho, Do-Hyeoun;Lee, Sang-Hyo
    • Journal of Institute of Control, Robotics and Systems
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    • v.4 no.1
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    • pp.1-9
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    • 1998
  • This paper is focussed on the problem of robustly stabilizing a transformable linear time-varying system. The considered system is a class of state feedback transformable linear systems. First, the real linear time-varying system is transformed into the linear time invariant system composed with the time-invariant linear part and the time-varying uncertainty part. Second, the solution to a quadratic stabilization problem in the transformed linear system is give via' Lyapunov methods. Then this solution is used to construct a stabilizing linear control law for the real linear time-varying system.

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Asymptotic Stability of Discrete-Time Linear Systems with Time Varying Delays (시변시간지연을 갖는 이산시간 선형시스템의 점근안정도)

  • Song, Seong-Ho;Kim, Jeom-Keun
    • Proceedings of the KIEE Conference
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    • pp.641-643
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    • 1998
  • This paper deals with the stability of discrete time linear systems with time - varying delays in state. In this paper, the magnitude of time - varying delays is assumed to be upper-bounded. The stability of discrete time linear systems with time - varying delays in state is related with the stability of discrete time linear systems with constant time delay in state. To show this, a new Lyapunov function is proposed. Using this Lyapunov function, a sufficient condition for the asymptotic stability is derived.

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Eigenvalue Assignment for Linear Time-Varying Systems via Ackermann-like Formula (선형 시변 시스템의 고유치 지정을 위한 Ackermann형 공식)

  • 이호철;최재원
    • Journal of Institute of Control, Robotics and Systems
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    • v.9 no.3
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    • pp.186-195
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    • 2003
  • This paper deals with eigenvalue assignment techniques for linear time-varying systems as a way of achieving feedback stabilization. For this, the novel eigenvalue concepts, which are the time-varying counterparts of the conventional (time-invariant) eigenvalue notions, are introduced. Then, the Ackermann-like formulae for SISO/MIMO linear time-varying systems are proposed. It is believed that these techniques are the generalized versions of the Ackermann formulae for linear time-invariant systems. The advantages of the proposed Ackermann-like formulae are that they neither require the transformation of the original system into the phase-variable form nor compute the eigenvalues of the original system. Two examples are given to demonstrate the capabilities of the proposed techniques.

Asymptotic Stability of Discrete Time Linear Systems with Time Varying Delays (시변시간지연을 갖는 이산시간 선형시스템의 점근안정도)

  • Song, Seong-Ho;Kim, Jeom-Keun;Kang, Chang-Ik
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.48 no.5
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    • pp.580-585
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    • 1999
  • This paper deals with the stability of discrete time linear systems with time varying delays in state. In this paper, the magnitude of time-varying delays is assumed to be upper-bouded. The stability of discrete time linear systems with time-varying delays in state is related with the stability of discrete time linear systems with constant time delay in state. To show this, a new Lyapunov function is proposed. Using this Lyapunov function, a sufficient condition for the asymptotic stability is derived.

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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.

A New Gain Scheduled QFT Method Based on Neural Networks for Linear Time-Varying System (선형 시변시스템을 위한 신경망 기반의 새로운 이득계획 QFT 기법)

  • Park, Jae-Seon;Im, Ki-Hong
    • Journal of Institute of Control, Robotics and Systems
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    • v.6 no.9
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    • pp.758-767
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    • 2000
  • The properties of linear time-varying(LTV) systems vary because of the time-varying property of plant parameters. The generalized controller design method for linear time-varying systems does not exit because the analytic soultion of dynamic equation has not been found yet. Hence, to design a controller for LTV systems, the robust control methods for uncertain LTI systems which are the approximation of LTV systems have been generally ised omstead. However, these methods are not sufficient to reflect the fast dynamics of the original time-varying systems such as missiles and supersonic aircraft. In general, both the performance and the robustness of the control system which is designed with these are not satisfactory. In addition, since a better model will give the more robustness to the controlled system, a gain scheduling technique based on LTI controller design methods has been uesd to solve time problem. Therefore, we propose a new gain scheduled QFT method for LTV systems based on neural networks in this paper. The gain scheduled QFT involves gain dcheduling procedured which are the first trial for QFT and are well suited consideration of the properties of the existing QFT method. The proposed method is illustrated by a numerical example.

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Stability Regions of Linear Slowly Time-Varying Systemsa (천천히 변하는 선형 시변 시스템의 안정도 영역)

  • 최종호;장태정
    • 제어로봇시스템학회:학술대회논문집
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    • pp.210-213
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    • 1988
  • By using Lyapunov method, sufficient conditions for linear time-varying continuous-time and discrete-time systems to be stable are presented under the assumption that the systems are slowly time-varying. Though it is not simple to find the stability regions immediately, one could find practical and large stability regions by constructing an appropriate algorithm.

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