This paper is concerned with the relationship between the gap metric and the time-varying gap metric for linear time-varying systems in the feedback configuration. It is shown that these two kinds of gaps are identica...
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This paper is concerned with the relationship between the gap metric and the time-varying gap metric for linear time-varying systems in the feedback configuration. It is shown that these two kinds of gaps are identical to each other when we measure the distance between corresponding graphs of a plant and a controller in a feedback system. This result supplies a simple way for computing the supremum appearing in the definition of the time-varying gap. Furthermore, the developed criteria are also applied to compute the optimal minimal angles of stabilizable linear time-varying systems.
In this paper, it is shown that the least squares algorithm with covariance reset, which is originally developed for the purpose of constant parameter identification, can be effectively applied to the observer design ...
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In this paper, it is shown that the least squares algorithm with covariance reset, which is originally developed for the purpose of constant parameter identification, can be effectively applied to the observer design for a general lineartime-varging system. The new observer successfully avoids many of the disadvantages of other time-varying observers, such as slow convergence rate, heavy computation load, high amplification of measurement noise, and the inapplicability to systems with time-varying observability indexes or discontinuous parameter variations.
In this paper the standard problem of H(infinity) control theory for finite-dimensional lineartime-varying continuous-time plants is considered. The problem is: given a real number-gamma > 0, find (if one exists) ...
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In this paper the standard problem of H(infinity) control theory for finite-dimensional lineartime-varying continuous-time plants is considered. The problem is: given a real number-gamma > 0, find (if one exists) an internally stabilizing controller such that the closed-loop operator norm is less than gamma. Under rather weak assumptions on the plant model, it is shown that a solution to this problem exists if and only if a pair of matrix Riccati differential equations admits positive semidefinite stabilizing solutions. State-space formulae for one solution to the problem are also given.
This paper studies the robustness properties of a basic adaptive control algorithm with respect to plant parameter variation as well as modeling errors and bounded disturbances. The algorithm consists of a projected g...
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This paper studies the robustness properties of a basic adaptive control algorithm with respect to plant parameter variation as well as modeling errors and bounded disturbances. The algorithm consists of a projected gradient estimator and a pole assignment controller, A unified method of proof is presented for robust stability of both discrete and continuous-time adaptively controlled time-varyingsystems, The robust performance of an adaptive pole assignment controller is also discussed.
For most of lineartime-varying (LTV) systems, it is difficult to design time-varying controllers in analytic way. Accordingly, by approximating LTV systems as uncertain lineartime-invariant, control design approache...
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For most of lineartime-varying (LTV) systems, it is difficult to design time-varying controllers in analytic way. Accordingly, by approximating LTV systems as uncertain lineartime-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 lineartime-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.
The technical note deals with existence conditions of a functional observer for linear time-varying systems in the case where the order of the observer is equal to the number of observed variables. Constructive proced...
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The technical note deals with existence conditions of a functional observer for linear time-varying systems in the case where the order of the observer is equal to the number of observed variables. Constructive procedures for the design of such a linear functional observer are deduced from the existence conditions. As a specific feature, the proposed procedures do not require the solution of a differential Sylvester equation. Some examples illustrate the presented results.
Recent results on the adaptive control of linear time-varying systems have considered mostly the case in which the range or rate of parameter variations is small. In this paper, a new state feed-back model reference a...
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Recent results on the adaptive control of linear time-varying systems have considered mostly the case in which the range or rate of parameter variations is small. In this paper, a new state feed-back model reference adaptive control is developed for systems with bounded arbitrary parameter variations. The important feature of the proposed adaptive control is an uncertainty estimation algorithm, which guarantees almost zero tracking error. Note that the conventional parameter estimation algorithm in the adaptive control guarantees only bounded tracking error. Copyright (C) 2000 John Wiley & Sons, Ltd.
Pole-zero cancellation is a well-known and important concept in lineartime-invariant systems. In contrast, transfer functions as well as poles and zeros are not defined for linear time-varying systems. In this paper,...
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ISBN:
(纸本)9784907764609
Pole-zero cancellation is a well-known and important concept in lineartime-invariant systems. In contrast, transfer functions as well as poles and zeros are not defined for linear time-varying systems. In this paper, we make an attempt to generalize the concept of pole-zero cancellation to linear time-varying systems. We firstly introduce the new concept of extended transfer function for linear time-varying systems in the time domain instead of the frequency domain. We then propose the computational procedure of pole-zero cancellation to linear time-varying systems. We finally discuss the meaning of the proposed computational procedure regardless of the lack of poles and zeros in linear time-varying systems. The proposed concept and computational procedure are illustrated by a numerical example.
New techniques are presented for the model reduction of lineartime-varying and linear periodically-varyingsystems, including the formulation and proof of guaranteed upper bounds for the error. The commonly used meth...
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ISBN:
(纸本)0780345304
New techniques are presented for the model reduction of lineartime-varying and linear periodically-varyingsystems, including the formulation and proof of guaranteed upper bounds for the error. The commonly used method of balanced truncation for lineartime-invariant systems is generalized to the time-varying case with explicit error bounds that are derived based on generalizations of the 'twice-the-sum-of-the-tail' formula. The development of these reduction results for time-varyingsystems relies on a new operator framework for analysis of linear time-varying systems, presented in [4], in combination with the model reduction methods for uncertain systems developed in [3].
The paper deals with the uniform finite-time stability (UFTS) of continuous lineartime-varying (LTV) systems. Firstly, a necessary and sufficient condition for the UFTS of continuous LTV systems is devised with the i...
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ISBN:
(纸本)9789881563958
The paper deals with the uniform finite-time stability (UFTS) of continuous lineartime-varying (LTV) systems. Firstly, a necessary and sufficient condition for the UFTS of continuous LTV systems is devised with the idea of computing the envelope of all the trajectories of the considered system. Then, a corollary is obtained under the perspective of numerical computation. Further, based on the obtained corollary, a novel numerical algorithm is designed by utilizing the Lipschitz continuity of certain functions. With the proposed algorithm, only limited numerical computation is needed when analyzing the UFTS of continuous LTV systems. Compared with the existing Lyapunov-like function method, one needn't constructing Lyapunov-like functions. Moreover, the obtained corollary just requires being checked at a limited number of time points. Finally, two numerical examples are provided to illustrate the effectiveness and superiority of the proposed results.
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