摘要:

Given a polynomialƒ(.s, k, q) which depends on the complex variable.s, a vector of design parameters kE Rmand a vector of uncertain parameters q e Q, we consider the following problem: Under what conditions does there exist a making Hurwitz-invariant? That is for all q e Qƒ(s, k*. q) has all its zeros in the strict left half-plane. In this paper, we develop sufficient conditions for ihe existence of k* and provide a ‘recipe’ for the construction of k* (whenever it exists). The conditions developed are seen to have an interesting control-theoretic interpretation.

ISSN:0020-7179    

DOI:10.1080/00207178908953414

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The estimation of the parameters of a transfer function model is considered. Relationships between the total least squares (TLS) and instrumental variable (IV) approaches are outlined. Both methods are able to compute strongly consistent parameter estimates. TLS can be considered as a variation on the IV method where the IV are functions of the time instant and the estimated model parameters. TLS computes strongly consistent estimates of the true model parameters if the outputs and possibly the inputs are independently disturbed by discrete, stationary white noise with zero mean and equal variance. The IV need not be generated. Hence TLS is much simpler to use but more restrictive (IV allows arbitrary noise models) and computationally not so attractive. Next, simulation results are presented comparing the short sample accuracy properties of both methods. When the outputs and possibly the inputs are disturbed by stationary zero mean while noise, TLS outperforms the ordinary IV methods. The accuracy becomes comparable by extending the IV sufficiently. The superiority of TLS is particularly clear in cases where the zeros of the polynomial operating on the outputs are close to the unit circle or where both the inputs and outputs are noisy.

ISSN:0020-7179    

DOI:10.1080/00207178908953415

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The current interest in robust control has called into question the applicability of the quantitative feedback theory (QFT) robust design method introduced by Horowitz. A number of issues have been raised regarding inherent restrictions of both the design method and the uncertain plant set. Using a multivariable root-locus technique extended to uncertain systems, this paper shows that the QFT assumptions are indeed not restrictive and are in fact equivalent to other well-known conditions for robust stabilizability. Because QFT is one of the very few methods to specifically address the quantitative robust performance issue, these results should lead to better methods of developing new QFT-design software, as well as improved robust control methods to satisfy a priori quantitative performance bounds.

ISSN:0020-7179    

DOI:10.1080/00207178908953416

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A simple criterion to detect the conditional stability of MI MO systems with integral control is described, It is shown that a closed-loop system with a loop-transfer matrix H(s)/s is made unstable by undesirable feedback-gain reduction if any of the principal minors of [si - H(0)] have zeros in the left half-plane.

ISSN:0020-7179    

DOI:10.1080/00207178908953417

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The existence and the synthesis of a stabilizing compensator for the diagonal decoupling of a linear multivariable system is examined. A new sufficient condition is established which is generically satisfied by any proper plant P and guarantees the existence of a stabilizing compensator that will give rise to a closed-loop transfer function matrix which is non-singular and diagonal.

ISSN:0020-7179    

DOI:10.1080/00207178908953418

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Using V as the time-delay operator, a linear invariant time-delay system is expressed by a quadruple (A(δ)), B(δ) C(V) D(V)) with the matrices over a polynomial ring in V. This paper studies the decoupling and coefficient assignment of such a system. For a class of time-delay systems non-controllable over the polynomial ring in V but controllable over the field of rational functions in V, we present sufficient conditions under which the system characteristic polynomial may be determined arbitrarily by feasible control laws. Two examples are investigated to illustrate the theory.

ISSN:0020-7179    

DOI:10.1080/00207178908953419

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The nearly decoupled design of time-invariant multivariable control systems is discussed. Part 1 deals with single-loop control systems design while Part 2 deals with multi-loop control systems design. In particular, Part 1 initially considers the case where the given plant has an equal number of inputs and outputs before exploring the case when a plant has more inputs than outputs. As a direct generalization of the classical approach, the proposed approach offers the designer the ability to choose the structure and specification of the compensator so that a trade-off between the cost and the performance of candidate designs can be made. Furthermore, it is shown that, when the plant has more inputs than outputs, the extra inputs can be used to reduce the required control effort without sacrificing the achieved performance. An optimization-based approach is then proposed to make the best use of the extra inputs.

ISSN:0020-7179    

DOI:10.1080/00207178908953420

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The design technique proposed in Part 1 is successfully developed to deal with multiloop control systems design. The inner loop is used to extend the frequency range of sensitivity reduction. In the case of a ‘square’ plant this inevitably leads to an excessive noise-response bandwidth. However, it is discovered that the noise response within the inner loop can be reduced considerably by the use of extra output measurements. Again, the standard model-matching problem plays a vital role in the design of a control system with a ‘tall’ plant.

ISSN:0020-7179    

DOI:10.1080/00207178908953421

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

An H∞ filter is presented for a class of multivariable systems. The Hm filtering problem is embedded in an L2estimation problem which is then decoupled by diagonalisation of the polynomial matrix estimation criterion. The filter is obtained in closed form.

ISSN:0020-7179    

DOI:10.1080/00207178908953422

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A robust model reference adaptive control scheme for bilinear plants with bounded disturbances is developed. Global stability of the closed-loop adaptive system is guaranteed by using a switching-σ modified adaptive law. In the absence of disturbances, the tracking error is shown to go to zero asymptotically with time.

ISSN:0020-7179    

DOI:10.1080/00207178908953423

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor