摘要:

This paper is a continuation of the research efforts reported recently in Yeung and Chen (1989) and Yeung and Chen (1991). This present work presents an extension of the sliding-mode control design method to multi-link flexible manipulators. There are two main steps in the design procedure, linearization and stabilization. In the linearization step, the sliding-mode technique is used to replace the rigid part of the dynamic equations by a set of linear equations which are determined by the switching surfaces. In the stabilization step, conventional PD/PID compensations are adopted to stabilize the linearized time-invariant system in the following three cases: (1) first-link ramp-tracking of the manipulator on a horizontal plane, (2) first-link parabola-tracking of the manipulator on a horizontal plane, and (3) first link regulation of the manipulator in a vertical plane. The developed sliding-mode controller is simple and requires no inertia matrix inversion, no modal estimation and no payload forecast. Simulation studies have been conducted to demonstrate the robustness of the controller against both input disturbances and payload variations.

ISSN:0020-7179    

DOI:10.1080/00207179108934159

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

This paper presents a practical design for hybrid adaptive control which does not need any numerical integration and is not destabilized by computational delays for parameter estimation. The controller consists of two simultaneously executing parts, that is, a control part and an estimation part. The estimation part searches the maximum estimation error over a successive time interval repeatedly. Based on this maximum error, the estimators for the unknown parameters of the plant are adjusted without any numerical integration. After the adjustment, the adjusted estimators are transported to the control part and are used to control the input generation over an interval, which differs from the interval for estimation since computational time is necessary for estimator adjustment. We show analytically and numerically that the computational burden of the proposed system is less than the usual hybrid adaptive system and that the proposed adaptive control system is globally stable in spite of including a time delay for the estimator adjustment in the control system.

ISSN:0020-7179    

DOI:10.1080/00207179108934160

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A robust long-range adaptive controller incorporating soft input constraints is considered. For the regulation case, the convergence of the algorithm is illustrated by means of simulations on ARMAX plants with unmodelled dynamics. An example of application is presented for the control of neuromuscular blockade induced by short-acting relaxants in patients under surgery.

ISSN:0020-7179    

DOI:10.1080/00207179108934161

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The phenomena of bounded and unbounded impulse transmission behaviours are investigated in this paper. It is discovered that these transmission behaviours have a strong connection with the unbounded asymptotic root loci and the locations of the infinite zeros. A unified conceptual framework is then established to interpret the physical significance of the unbounded asymptotic root loci and the locations of the infinite zeros of a linear time-invariant multivariable system.

ISSN:0020-7179    

DOI:10.1080/00207179108934162

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The least mean squares (LMS) algorithm is analysed as a control system rather than the conventional statistical approach. This approach greatly simplifies the understanding of the problem and presents a more convenient way of performing stability and convergence analysis. It is shown that the gain required for stability, i.e. the step size, derived using control theory is exactly the same as the result obtained by Widrowet al. (1979). It is also shown that the above gain value does not have to be constant but can vary at each iteration by the use of a sliding rectangular window whose length is equal to the number of parameters of the model. Furthermore, the gain of the system can be increased by the addition of integrators. The classical control approach was used to stablize the system, i.e. by considerations of phase advance, span ratios and system bandwidth.

ISSN:0020-7179    

DOI:10.1080/00207179108934163

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The gain margin for a multivariable system is defined by examining the positive definite hermitian (p.d.h.) portion of the polar decomposition of a non-singular perturbation, A, in the feedback path. Thedualresult defining the phase margin for a multivariable system has been derived by Bar-on and Jonckheere (1990) by examining the unitary portion of the polar decomposition for non-singular perturbations. This paper focuses on the multivariable gain margin, The main result is an extension of the classical SISO concept of gain margin to MIMO systems. The definition for gain margin presented encompasses both gain reduction and gain amplification tolerance because the measurement is relative to the identity matrix as opposed to zero. Closed loop stability is guaranteed for all p.d.h. matrices in the feedback path whose gain, relative to the identity matrix, is less than the gain margin of the system. Calculation of the gain margin requires solving a constrained optimization problem which is almost a completedualof the constrained optimization problem solved when calculating the phase margin (see Bar-on and Jonckheere 1990).

ISSN:0020-7179    

DOI:10.1080/00207179108934164

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

This paper is concerned with the linear partial differential equation describing the motion of the Timoshenko beam with viscous internal dampings and with a certain type of boundary inputs. The equation is formulated as an evolution equation of the form dz( t)/dt = — Az( i) in a Hilbert space, and then it is proved for the linear operator — A to generate an analytic semigroup. Moreover, the stability of the boundary control system is examined. It is shown that in some cases the present type of boundary inputs degrades the degree of stability of the system. This is a remarkable contrast to the results of previous research which states that the same type of boundary inputs are effctive in stabilizing the Timoshenko beam without any structural damping.

ISSN:0020-7179    

DOI:10.1080/00207179108934165

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A fundamental role in the equalizing approach ℋ∞to optimal control is assumed by solutions which together with a related spectral density satisfy the so-called equalizer principle, a sufficient condition for minimality of the largest singular value. The paper gives a characterization of the equalizer principle, which in the one-block case leads to a close connection between the spectral density and the maximizing vectors of the Sarason-type operator associated with the problem. This extends via dimension reducing techniques the equalizing approach to a super-optimization procedure for the one-block problem.

ISSN:0020-7179    

DOI:10.1080/00207179108934166

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A new method of determining the optimal control for non-linear systems is described. It employs a novel course correction mechanism to optimize the state with respect to the initial condition and then uses dynamic programming to optimize the control with respect to the final condition. A non-linear closed-form relationship of the cost function was developed so that the multi-grid approach of dynamic programming is avoided. Unlike other solution methods for optimal control problems, it does not need an estimate of the nominal solution to start the algorithm. One backward pass generates the optimal state trajectory, which is then tracked during the execution of the manoeuver. Compared to the multipasses necessary for other methods, this new method provides a significant improvement in computation time.

ISSN:0020-7179    

DOI:10.1080/00207179108934167

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

This paper presents a method for finding the boundaries of gain margins and phase margins of multivariable control systems with adjustable parameters. The considered systems are first decomposed into the augmented open-loop transfer functions modified by adding an analytical gain-phase margin tester, then the characteristic equations are formulated, and finally the stability equations are used to find the boundaries of constant gain margins and phase margins. The main advantage of the proposed method is to obtain complete information about the effects of adjustable parameters on gain margins and phase margins; thus it is a useful tool for analysis and design of robust control systems,

ISSN:0020-7179    

DOI:10.1080/00207179108934168

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor