摘要:

In parameter identification of robot manipulators, measurement noise from acceleration and velocity, together with unmodelled dynamics, are the main sources of errors in the least-squares estimation and can also considerably increase the time necessary for parameter convergence. Instead of using Instrumental Variables or filtered estimates of the acceleration, we discuss the application of a repetitive controller in order to minimize estimation bias caused by measurement noise. We prove that the controller converges to a neighbourhood of the desired trajectory, taking into account measurement and actuator noise. Thus, desired values of acceleration and velocity can be used in the regression vector as estimates of their real values. The method is applied in the parameter estimation of a direct-drive arm, experimental issues are discussed and the validity of the results are experimentally verified.

ISSN:0020-7179    

DOI:10.1080/00207179608921841

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A model reference control (MRC) method is presented for linear, time-invariant systems with unknown dynamics. The class of systems investigated can be described bywhere ΔA, ΔBandd(t) are unknown dynamics and unexpected disturbances, respectively. The design method is described in the discrete time form using the Euler operator, which approaches the Laplace operator as the sampling interval,T, approaches zero. The control is constructed, based on the estimation of system perturbations using time delay control (TDC), under the following two assumptions: (1) the dynamics stemming from the perturbations are considerably slower than the discretization frequency, 1/T; and (2) the control has access to all the plant states. The controller is tested through simulation and experiment. The theoretical and experimental results indicate that the proposed method has potential applications for controlling servo-mechanisms subjected to unknown and unexpected disturbances.

ISSN:0020-7179    

DOI:10.1080/00207179608921842

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

An algorithm for solving nonlinear discrete time optimal control problems with model-reality differences is presented. The technique uses Dynamic Integrated System Optimization and Parameter Estimation (DISOPE), which achieves the correct optimal solution in spite of deficiencies in the mathematical model employed in the optimization procedure. A version of the algorithm with a linear-quadratic model-based problem, implemented in the C+ + programming language, is developed and applied to illustrative simulation examples. An analysis of the optimality and convergence properties of the algorithm is also presented.

ISSN:0020-7179    

DOI:10.1080/00207179608921843

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

We propose a robust model reference tracking control design for non-holonomic mechanical systems under parametric perturbation and external disturbance. A design procedure with three-stage control is developed to solve the robust tracking problem for perturbative non-holonomic mechanical control systems. In the first stage, by a proper choice of transformation matrix, the perturbative non-holonomic mechanical system is transformed into a reduced form of non-holonomic mechanical system for the convenience of control design. In the second stage, based on the concept of ‘input/output decoupling’ in nonlinear control theory, a decoupled system with parameter perturbation and external disturbance is established via a nonlinear dynamic state feedback control. In the third stage,H ∞ criteria to specify desired model reference tracking performance in the face of parametric perturbation and external disturbance are proposed for the decoupled system.H ∞ controllers that achieve theseH ∞ tracking performance are also explicitly constructed. Finally, two typical non-holonomic examples—a knife edge and a vertical wheel moving on a given plane—are given with computer simulation to illustrate the significant advantages of the proposed method.

ISSN:0020-7179    

DOI:10.1080/00207179608921844

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Integral controllable systems can be stabilized by all sufficiently low-gain integral controllers. The concept of integral controllability is extended to two generalized stability regions and to proportional controllability and PI controllability with respect to those regions. Furthermore, closed eigenvalue formulae are derived for the maximal low integral gain and the maximal low proportional gain for generalized stability. Related eigenvalue formulae are then used in combination to find all low-gain PI controllers that place the closed-loop eigenvalues in the desired region.

ISSN:0020-7179    

DOI:10.1080/00207179608921845

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

In this paper, we outline the extension of the MOESP family of subspace model identification schemes to the Hammerstein-type of nonlinear system. Two types of identification problem are considered. The first type assumes the (polynomial) structure of the static nonlinearity to be given and the task is to identify both the linear system dynamics and the unknown proportional constants in the para-metrization of the static nonlinearity. The second type addresses the identification of both the linear dynamic part and the static nonlinearity, where only limited a priori information regarding the structure of the nonlinearity is available. The improved robustness properties of the algorithms developed for this second type of Hammerstein identification problem over existing correlation-based schemes is illustrated by a numerical example.

ISSN:0020-7179    

DOI:10.1080/00207179608921846

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

An exposition of the effects of sampling on the controllability characteristics and the Kronecker invariants of the plant and the input matrices of sampled-data systems is presented. In particular, the effect of sampling period on the feedback matrix for time-optimal control of sampled-data systems is investigated in detail, and it is shown that different classes of systems produce different response characteristics as the sampling period becomes large. Also, simple expressions forA(NT) in terms ofA(T), andB(NT) as a function ofA(T) andB(T), are derived. These expressions are computationally attractive and therefore facilitate the study of the effect of sampling period on system behaviour. By applying these expressions, the effects of sampling period on the feedback matrices for time-optimal control of three classes of systems whose open-loop plants are asymptotically stable, marginally stable, and unstable, are illustrated by numerical examples.

ISSN:0020-7179    

DOI:10.1080/00207179608921847

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The purpose of this paper is to outline a polynomial approach to modelling and analysing multi-rate control systems. A certain class of system, in which the data input to a digital controller are sampled at a faster rate than the data output, is chosen to illustrate the technique. A set of difference equations defining the propagation of variables during the repetitive time interval engenders a system description whereby the corresponding operations are defined as polynomial functions of the backward-shift operatorq−1. This representation circumvents difficulties associated with theZN-transform approach, engendering simple methods of assessing closed-loop stability and assigning poles. Finally, attention is focused upon system performance in the presence of deterministic and stochastic input signals. An example is employed throughout the paper to illustrate developments in the theory.

ISSN:0020-7179    

DOI:10.1080/00207179608921848

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

This paper demonstrates a fuzzy sliding mode control (FSMC) scheme for a static reactive power compensator (static VAR compensator or SVC) to improve the damping of a synchronous generator. A robust sliding regime is derived to guarantee the stability of the proposed FSMC under parameter uncertainties. Two types of FSMC, the fuzzy switching gain compensation and the fuzzy control signal compensation, are recommended to regulate the reactive power of the SVC. A synchronous generator system with the proposed FSMC-SVC has been studied and its dynamic responses are simulated. The results show that the suggested FSMC scheme possesses the advantages of fuzzy control and sliding mode control, e.g. insensitivity to parameter variations and load disturbances. Note that the dynamic performance of the synchronous machine system can be improved dramatically over a wide range of operating conditions. Furthermore, for simplification of practical implementation, the reducing switches (or local feedback) control is adopted.

ISSN:0020-7179    

DOI:10.1080/00207179608921849

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor