摘要:

A dynamic feedback controller will be proposed to treat the trajectory tracking control problem of robotic manipulators with flexible joints that use only position measurements on the link and motor sides. Previously published results for the tracking control problem without velocity measurements address only the rigid robot design. Moreover, these results are based on a full-order observer whose dimension is equal to the dimension of the robotic systems. In contrast, our solution can be applied to treat the robotic systems with flexible joints. It does not require any restriction on the joint stiffness. The proposed controller is based on a reduced-order observer which is constructed only to estimate the velocity signal and whose dimension is half of the dimension of flexible-joint robotic systems. We shall show that the resulting closed-loop error system is locally exponentially stable with an arbitrarily large region of attraction. The convergence rate can be arbitrarily pre-assigned and the attraction region not only can be pre-assigned but also can be explicitly constructed. Moreover, as the unknown uncertainties are concerned, the robustness of the closed-loop system is also discussed. Finally, simulation results are included to demonstrate the tracking performance.

ISSN:0020-7179    

DOI:10.1080/00207179608921644

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

In this paper, we consider the optimal simultaneous stabilization problem for a collection of linear time-invariant descriptor systems. The objective function for the collection of systems is defined to be the sum of all quadratic objective functions associated with individual systems. The problem is to choose an output feedback gain such that the objective function is minimized. Firstly, the set of all the output feedback gains for which the objective function is finite is characterized and proven to be a compact set. Secondly, an iterative algorithm based on the gradient flow idea is derived for solving this problem and some properties on the gradient flow are obtained to guarantee the success of this method. Thirdly, an initial value for the gradient flow equation is found by solving a standard unconstrained optimization problem. Finally, two numerical examples are solved for illustration.

ISSN:0020-7179    

DOI:10.1080/00207179608921645

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

This work studies various types of input-output representation for analytic input-output operators. It is shown that if an operator satisfies an integro-differential input-output equation or an integral input-output equation, then it is locally realizable by analytic state space systems. This generalizes the results previously obtained for differential input-output equations to integral and integro-differential equations.

ISSN:0020-7179    

DOI:10.1080/00207179608921646

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Systems, such as those subject to abrupt changes (including failure) or those with uncertain dynamic model (or more than one possible model), can be naturally modelled as jump linear (JL) systems. Because of their applications in fields such as tracking, fault-tolerant control, manufacturing process and robots, JL systems have drawn extensive attention. The optimal control and stabilization problem for JL systems, when the mode (system model) is not assumed to be directly and perfectly observed, a realistic assumption in many applications, is nonlinear and prohibitive both analytically and computationally because of the dual effect. The main contribution of this work is the sufficient condition for stabilization for a class of adaptive controllers when the mode is not directly observed. We first present the optimal controller under an assumption of a certain type of mode availability. Using this optimal feedback gain, we derive a condition that ensures the stabilizing property for a class of adaptive controllerswithoutdirect knowledge of the mode. Two specific adaptive controllers (maximuma posterioriand averaging) are examined in detail and their stabilizing property is proved. An algorithm to compute the optimal feedback gain and its convergence are presented. Examples show that the performance of the adaptive controllers without mode observations derived here is very close to that of the optimal controller with known modes.

ISSN:0020-7179    

DOI:10.1080/00207179608921647

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Modern techniques for dynamic control of chaotic systems are introduced. The problem of controlling chaos is addressed in the same conceptual framework as proposed by Ott, Grebogi and Yorke. However, the novelty here is the introduction of LQ and ℋ∞techniques to address the problem. These techniques have been tested on representative systems, specifically the Logistic Map.

ISSN:0020-7179    

DOI:10.1080/00207179608921648

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

In this paper, the process of controller design for nonlinear systems, using linear synthesis techniques, is examined. Specifically, proportional and integral control of nonlinear systems is investigated. The crucial role of integral action in linearization-based controller design for nonlinear systems is highlighted.

ISSN:0020-7179    

DOI:10.1080/00207179608921649

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

We develop a ‘multiple-surface’ sliding control for a class of single-input single-output nonlinear systems whose uncertainties do not satisfy the standard matching condition. A coordinate dependence condition on the uncertainty bound is assumed. A ‘computed normal form’ is defined to handle such uncertainties instead of the normal form used in conventional input-output linearization. A control algorithm which can be applied to global tracking problems has been developed and evaluated for a benchmark example.

ISSN:0020-7179    

DOI:10.1080/00207179608921650

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The objective of this paper is to use a Lyapunov function to study the stability of a loop system containing a single nonlinearity in an infinite sector angle. We obtain necessary and sufficient conditions for the existence of a Lyapunov function with ‘ a quadratic form plus an integral term’, which is a generalization of the Popov frequency criterion and Curran's papers. A numerical example illustrates the advantage of the obtained criteria.

ISSN:0020-7179    

DOI:10.1080/00207179608921651

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

In this paper the Clarke-Gawthrop type of self-tuning controller is modified and shown to be robust stable with respect to unmodelled plant uncertainties and bounded disturbances. A self-tuning controller is proposed here consisting of two steps: the first, an optimal control law, is derived by means of minimizing a quadratic cost function of the Clarke-Gawthrop type; the second, the optimal control law, is modified by introducing an estimate of the modelling error as a feedback. For the parameter estimation, a modified least-squares scheme with a relative dead zone is employed. The robustness results are derived by neither requiring too much a priori knowledge of the plant parameters, nor using any assumptions about the adaptive signals.

ISSN:0020-7179    

DOI:10.1080/00207179608921652

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The paper considers the problem ofH2optimal approximation of a high-order system by a low-order system with delay. An algorithm to solve this problem is presented. It consists of optimization with respect to the delay only where the rational part of the model and the quadratic cost are given by a solution of an equivalent order reduction problem without delay. It is shown by means of an example that introduction of delay into the model leads, in certain cases, to considerable improvement in the approximation. The results are extended to multiple-input multiple-output systems and also to frequency-weighted order reduction.

ISSN:0020-7179    

DOI:10.1080/00207179608921653

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor