• Title/Summary/Keyword: 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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Stability Bound for Time-Varying Uncertainty of Positive Time-Varying Discrete Systems with Time-Varying Delay Time (시변 지연시간을 갖는 양의 시변 이산시스템의 시변 불확실성의 안정범위)

  • Han, Hyung-Seok
    • Journal of Institute of Control, Robotics and Systems
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    • v.22 no.6
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    • pp.424-428
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    • 2016
  • A simple new sufficient condition for asymptotic stability of the positive linear time-varying discrete-time systems, with unstructured time-varying uncertainty in delayed states, is established in this paper Compared with previous results that cannot be applied to time-varying systems; the time-varying system and delay time are considered simultaneously in this paper. The proposed conditions are compared with suitable conditions for the typical discrete-time systems. The considerations are illustrated by numerical examples of previous work.

Stability of Time-Varying Discrete State Delay Systems (이산 시변 상태지연시스템의 안정성)

  • Suh, Young-Soo
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.51 no.2
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    • pp.43-47
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    • 2002
  • Stability conditions of time-varying discrete state delay systems are proposed. The time-varying state delay is assumed that (i) the magnitude is known to lie in a certain interval (ii) the upper bound of the rate of change is known. Under these conditions, new stability conditions are derived based on switched Lyapunov functions. Stability conditions for both fast time-varying and slowly time-varying delay are considered.

Utilization of the Filtered Weighted Least Squares Algorithm For the Adaptive Identification of Time-Varying Nonlinear Systems (적응 FWLS 알고리즘을 응용한 시변 비선형 시스템 식별)

  • Ahn Kyu-Young;Lee In-Hwan;Nam Sang-Won
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.53 no.12
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    • pp.793-798
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    • 2004
  • In this paper, the problem of adaptively identifying time-varying nonlinear systems is considered. For that purpose, the discrete time-varying Volterra series is employed as a system model, and the filtered weighted least squares (FWLS) algorithm, developed for adaptive identification of linear time-varying systems, is utilized for the adaptive identification of time-varying quadratic Volterra systems. To demonstrate the performance of the proposed approach, some simulation results are provided. Note that the FWLS algorithm, decomposing the conventional weighted basis function (WBF) algorithm into a cascade of two (i.e., estimation and filtering) procedures, leads to fast parameter tracking with low computational burden, and the proposed approach can be easily extended to the adaptive identification of time-varying higher-order Volterra systems.

Robust $H_{\infty}$ FIR Sampled-Date Filtering for Uncertain Time-Varying Systems with Unknown Nonlinearity

  • Ryu, Hee-Seob;Byung-Moon;Kwon, Oh-Kyu
    • Transactions on Control, Automation and Systems Engineering
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    • v.3 no.2
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    • pp.83-88
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    • 2001
  • The robust linear H(sub)$\infty$ FIR filter, which guarantees a prescribed H(sub)$\infty$ performance, is designed for continuous time-varying systems with unknown cone-bounded nonlinearity. The infinite horizon filtering for time-varying systems is systems is investigated in therms of two Riccati equations by the finite moving horizon.

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Adaptive control of time varying system (시변시스템의 적응제어에 관한 연구)

  • 곽유식;양해원
    • 제어로봇시스템학회:학술대회논문집
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    • 1988.10a
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    • pp.264-267
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    • 1988
  • One of the major reasons of Adaptive Control is to control time varying systems. In this paper new adaptive algorithms are suggested for a class of linear time varying systems that satisfy certain assumptions. These algorithms consist of three modules, modeling, parameter estimation and control. The key feature of this paper is that power series of time varying parameters are used for estimation.

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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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Robust $H^{\infty}$ control for parameter uncertain time-varying systems with time-varying delays in state and control input (파라미터 불확실성 시변 시간지연 시스템에 대한 견실 $H^{\infty}$ 제어)

  • 김기태;김종해;박홍배
    • 제어로봇시스템학회:학술대회논문집
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    • 1997.10a
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    • pp.113-116
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    • 1997
  • In this paper, we present a robust $H^{\infty}$ controller design method for parameter uncertain time-varying systems with disturbance and that have time-varying delays in both state and control. It is found that the problem shares the same formulation with the $H^{\infty}$ control problem for systems without uncertainty. Through a certain differential Riccati inequality approach, a class of stabilizing continuous controller is proposed. For parameter uncertainties, disturbance and time varying delays, proposed controllers the plant and guarantee an $H^{\infty}$ norm bound constraint on disturbance attenuation for all admissible uncertainties. Finally a numerical example is given to demonstrate the validity of the results.ts.

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Delay-Dependent Robust Stabilization and Non-Fragile Control of Uncertain Discrete-Time Singular Systems with State and Input Time-Varying Delays (상태와 입력에 시변 시간지연을 가지는 불확실 이산시간 특이시스템의 지연종속 강인 안정화 및 비약성 제어)

  • Kim, Jong-Hae
    • Journal of Institute of Control, Robotics and Systems
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    • v.15 no.2
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    • pp.121-127
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    • 2009
  • This paper deals with the design problem of robust stabilization and non-fragile controller for discrete-time singular systems with parameter uncertainties and time-varying delays in state and input by delay-dependent Linear Matrix Inequality (LMI) approach. A new delay-dependent bounded real lemma for singular systems with time-varying delays is derived. Robust stabilization and robust non-fragile state feedback control laws are proposed, which guarantees that the resultant closed-loop system is regular, causal and stable in spite of time-varying delays, parameter uncertainties, and controller gain variations. A numerical example is given to show the validity of the design method.