摘要:

In this paper we examine the stability properties of linear multivariable feedback systems in the presence of structured additive perturbations characterized by dependencies occurring in the perturbation matrix. Such dependencies may take the form of dependent phases between elements of element-by-element bounded perturbations and/or repeated blocks in block-structured perturbations. By using non-diagonal and possibly complex transformation matrices, it is shown how stability conditions that are both necessary and sufficient may be obtained for this class of perturbation.

ISSN:0020-7179    

DOI:10.1080/00207178608933563

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Classical ‘sliding mode control’, as investigated mostly in Soviet literature, features excellent robustness properties in relation to parametric uncertainty, but presents several important drawbacks that severely limit its practical applicability. These drawbacks, including large control authority and control chattering, were remedied by Slotine and Sastry (1983) and Slotine (1984) by replacing control switching at a fixed sliding surface by a smooth control interpolation in a boundary layer neighbouring a time-varying sliding surface. This avoids the excitation of high-frequency unmodelled dynamics, and leads to an explicit trade-off between model uncertainty and controller tracking performance. The present paper examines how to further improve performance by effectively coupling on-line parameter estimation to sliding controller design. The boundary layer concept leads to a compact measure of the quality of parameter estimation, and provides a consistent rule on when to stop adaptation. The approach is demonstrated by simulations.

ISSN:0020-7179    

DOI:10.1080/00207178608933564

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The result of exact model matching for delay systems developed by the author is extended to the adaptive control of delay systems. Likewise, using results from the adaptive control of systems without delay, the principle of constructing adaptive systems for delay plants is also very simple and clear.

ISSN:0020-7179    

DOI:10.1080/00207178608933565

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

In this paper, we propose a new type of inverse called the filtered inverse. This inverse reconstructs the approximate value of the input to the original system without differentiators. The definition and the existence condition of the filtered inverse are given first. Then the stability and minimal realization of the inverse are discussed. Also, the stability of conventional inverses without differentiators are examined to show the necessity for filtered inverses. Furthermore, the application of such an inverse to servo system synthesis is discussed.

ISSN:0020-7179    

DOI:10.1080/00207178608933566

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A computationally efficient method, which uses finite orthogonal expansions to approximate state and control variables, is developed to obtain suboptimal control for time-varying systems with multiple state and control delays and with quadratic cost. Shifted Legendre polynomials form the basis of expansions as a consequence of their useful properties. The Galerkin method is used to reduce the problem to one of minimizing a quadratic form with linear algebraic constraints. The solution of a coupled two-point boundary-value problem with both delayed and advanced terms, which is always required in applying the Pontryagin's maximum principle to the optimization of delay systems, is thus avoided.

ISSN:0020-7179    

DOI:10.1080/00207178608933567

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Motivated by a control system example, a new methodology is proposed for tackling optimal design of engineering systems. This methodology emphasizes designer's intuition and man-machine interaction. It includes a classification of specifications into various types and a scaling of specification space and parameter spaces based on the designer's knowledge of the particular application. An algorithm is proposed for solving the resulting constrained ‘minimax’ optimization problem and its convergence is proved. Finally, an application-oriented user front-end is presented. The methodology discussed in this paper has been implemented in the DELIGHT system and has been successfully used in various types of applications.

ISSN:0020-7179    

DOI:10.1080/00207178608933568

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The concepts of controllability and stabilizability subspaces are extended to infinite-dimensional linear systems. Under certain assumptions one obtains a nice generalization of the finite-dimensional theory, and, by dualizing, similar results are obtained for the concepts of complementary observability and complementary detectability subspaces. These concepts are used to solve the infinite-dimensional version of the disturbance-decoupling problem, the disturbance-decoupled estimation problem and the disturbance-decoupling problem with measurement feedback, all requiring various stability requirements. The solution is in terms of geometric concepts such as (A, B)- and (C,A)- invariant subspaces and controllability and complementary observability subspaces.

ISSN:0020-7179    

DOI:10.1080/00207178608933569

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

This paper highlights some difficulties with the use of ARMA models with leading unit coefficient matrix in system identification. It is shown that the McMillan degree of such models is not in any easy way related to the row degrees of the polynomial factors of the ARMA model. A rank test is given for the McMillan degree of such models and it is shown that this degree will generically be a multiple of the dimension of the observation vector.

ISSN:0020-7179    

DOI:10.1080/00207178608933570

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The differential matrix Riccati equation for the multi-input-multi-output linear quadratic optimal regulator problem is considered. Two methods are presented, successive and parallel, that decompose this equation into a set of Riccati equations that correspond to optimal regulator problems of possibly reduced dimensions. The additivity of the solutions to the equations obtained by the successive sequential decomposition method (SDM) and the additivity of the inverses of the solutions to the equations obtained by the parallel SDM are established. Some duality relations between the successive and the parallel methods are presented via the use of the adjoint Riccati equation. The theory developed is extended to the algebraic matrix Riccati equation as a limiting case. The application of the SDMs in the infinite-time linear quadratic regulator problem is investigated. Special attention is paid to the partially ‘cheap’ problem where the cost of some of the regulator controls or of their combinations tends asymptotically to zero. Explicit expressions for the asymptotic optimal cost are derived and the behaviour of the asymptotic optimal root loci is investigated.

ISSN:0020-7179    

DOI:10.1080/00207178608933571

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A set of generalized orthogonal polynomials (GOPs) that can represent all types of orthogonal polynomial and non-orthogonal Taylor series are first introduced to solve dynamic state equations with two-point-boundary conditions. The basic idea is that any orthogonal polynomial function can be expressed as a power series, and vice versa. The operational matrix for the integration of the generalized orthogonal polynomials is thus derived. Using the special characteristics of these generalized orthogonal polynomials, the state equation of the two-point-boundary-value problem is thus reduced to that of an initial-value problem. This effective approach can be applied to solve the optimal control of a lumped or distributed parameter system. The computational algorithm, in conjunction with the recursive formula, is much simpler and easier than that for conventional individual orthogonal polynomials.

ISSN:0020-7179    

DOI:10.1080/00207178608933572

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor