摘要:

The stabilization of a class of sampled-data systems by slow sampling is studied. A relationship is obtained between the minimum sampling period and an estimated domain of attraction of the system.

ISSN:0020-7179    

DOI:10.1080/00207179008934062

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

An energy-based, continuous-valued measure of interaction between the input and output channels of a linear constant system is formulated and used as the basis for a theory of near disturbance localization for discrete-time systems. The generalized disturbance localization problem is formulated as the minimization problem of finding the feedback gain matrixFfor which this interaction measure is minimized. The solutions obtained are shown to correspond where appropriate with those predicted by the geometric state-space approach. Connections are made, too, to results on system invertibility and on ‘cheap’ linear-quadratic control problems.

ISSN:0020-7179    

DOI:10.1080/00207179008934063

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

We present a general lemma to investigate the uniform b⊙undedness of the solutions of a class of discrete-time dynamic systems. In practical terms, this lemma allows a demonstration of the bounded-input-bounded-output (BIBO) robust stability of all the available discrete-time adaptive (linear) control systems.

ISSN:0020-7179    

DOI:10.1080/00207179008934064

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

For a class of non-linear dynamic systems, a quadratic regulator problem is considered in which the cost functional contains a small parameter multiplied to the control term. In the analysis of the problem, an appropriate transformation of the state variables and an eigenvector technique are utilized, which were devised originally for analysing complex linear cheap control problems and for solving a Lyapunov-type system of linear equations, respectively. In so doing, the class of nonlinear systems is characterized and extended in a mathematically simple way, for which the optimal cost becomes zero as the small parameter goes to zero.

ISSN:0020-7179    

DOI:10.1080/00207179008934065

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A simple adaptive control algorithm is presented which is applicable to multi-variable systems with a general time-delay structure. The proposed algorithm has the advantage that it only requiresa prioriknowledge of integer-valued parameters (i.e. time delays and order parameters). It is shown that, with probability one, the algorithm will ensure the system inputs and outputs are sample mean-square bounded and the conditional mean-square generalized output tracking error achieves its global minimum possible value for linear feedback control. Some simulation results are presented to demonstrate the performance of the algorithm.

ISSN:0020-7179    

DOI:10.1080/00207179008934066

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The gain perturbation tolerance property ofH∞-optimal state feedback (HISF) systems is considered. The following two problems are discussed: (1) for what gain perturbations would the perturbed closed-loop system remain stable? (2) for what gain perturbations would the perturbed closed-loop transfer function satisfy the specifiedH∞norm performance? In each case we establish general sufficient conditions in the frequency domain. In particular, under a certain orthogonality condition, the HISF systems are shown to possess an infinite gain increase tolerance for stability. The result obtained also provides insight into the gain reduction tolerance problem. Furthermore, we show that, under certain conditions, the specifiedH∞-norm performance of the HISF systems is preserved even with an infinite gain increase. Concerning closed-loop performance robustness against gain perturbations, we see remarkable differences between the case where controlled outputs include a direct transmission of controls and the case where they do not.

ISSN:0020-7179    

DOI:10.1080/00207179008934067

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A complete parametrization of all stabilizing IMC controllers for open-loop unstable plants is presented. Within this general setting the class of all steady-state offset free IMC controllers for asymptotically constant inputs is given.

ISSN:0020-7179    

DOI:10.1080/00207179008934068

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A sampled-data control scheme is developed for an unstable time-delayed process, in order to circumvent the limitation on stabilizability (de Paor 1985, de Paor and O'Malley 1989, de Paor and Egan 1989) imposed by the parameter ϵ = λL, where λ > 0 is the unstable pole location in thes-domain andLis process latency. A Luen-berger observer is used for initial assignment of eigenvalues, with disturbance-rejecting PI or PID control then added. The adverse effect of ϵ on disturbance rejection is highlighted. This parameter is seen as a genuine index of difficulty in control, whichever approach is adopted. The effect of derivative action on stability is considered via root locus; no compelling case for its incorporation is established.

ISSN:0020-7179    

DOI:10.1080/00207179008934069

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Sufficient conditions of stability are described for a multiloop system if the controllers are designed from simplified models. A graphical test criterion for each loop which will guarantee the stability of the system is given for a simplified non-interacting model. A simple example illustrates these results.

ISSN:0020-7179    

DOI:10.1080/00207179008934070

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

We study the multivariable loop-shaping problem when the plant is ill-conditioned and feedback properties at both plant input and output are of interest. Directionality and coupling are described, using the singular value decomposition and principal angles between high- and low-gain subspaces. Our first results are new first-order approximations to feedback properties at one loop-breaking point in terms of the open loop transfer function at that point. Secondly, we study the relation between feedback properties at different loop-breaking points in the event that the plant is ill-conditioned. The nominal relation is studied first. Then robustness is studied, using a first-order approximation to feedback properties at one point with respect to uncertainty at the other. This analysis yields conditions that must be satisfied by feedback properties at one point to prevent poor feedback properties at the other. Finally, these two sets of results are combined to show how feedback properties at both points may be manipulated by shaping the open loop transfer function at one point.

ISSN:0020-7179    

DOI:10.1080/00207179008934071

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor