摘要:

It has become common practice, in recent years, that the model-based computed torque method is adopted for the tracking control of robotic manipulators. However, high precision tracking is possible only in the case of perfect or almost-perfect modelling. In this paper, a novel scheme is proposed to enhance the existing model-based method. It is based on the combination of the classical serial pre-compensation of the computed torque method and a model-based parallel post-compensation approach. The resulting system has a simple structure with good robustness. Several problems associated with the practical implementation of the developed method are addressed. Numerical examples and comparative studies demonstrate that the presented approach can outperform the conventional method.

ISSN:0020-7179    

DOI:10.1080/00207179208934365

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The complexity of a large scale system makes the computations of reduced order models based on balancing impractical. However, typically there is a weak coupling between the subsystems of a large scale system. This is used here to derive approximate balanced-truncation reduced order models for large scale systems with reliable and tractable computations.

ISSN:0020-7179    

DOI:10.1080/00207179208934366

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Parallel algorithms play a crucial role in utilizing parallel computers to overcome the difficulties of computation intensive problems. This paper presents a new parallel algorithm for solving optimal control of discrete-time interconnected systems. The idea is to use Lagrange multipliers to relax the coupling among subsystems. The decomposed subproblems are solved in parallel by using the differential dynamic programming (DDP) method. The Lagrange multipliers are selected as coordinating variables and updated at the high level to ensure global optimality. A method for estimating the computational complexity of the decomposition/coordination approach is presented, and the relationship between speed-up and major system parameters is established. It is shown that significant speed-ups are difficult to achieve by using conventional optimization techniques at high level. A large number of high level iterations may offset the reduction in computation for dealing with smaller decomposed subproblems in parallel. The parallel variable metric (PVM) method is found to be a promising high level algorithm for loosely coupled systems. Numerical results show that comparing with one level DDP, the PVM/DDP algorithm obtains significant speed-ups under a simulated parallel processing environment. Moreover global variational feedback controls which are invaluable for on-line control systems are obtained.

ISSN:0020-7179    

DOI:10.1080/00207179208934367

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

In this paper we consider the model reference adaptive control problem of single-input single-output linear, time-varying plants. We assume that the plant parameters are uniformly bounded and piecewise Lipschitz continuous. Inside the intervals of continuity, we assume that the plant satisfies certain controllability, observability, relative degree and zero dynamics assumptions but the speed of parameter variations is not restricted to be small. Under these general conditions we design a control law of the model reference type which guarantees the boundedness of the closed-loop plant and small tracking error in the mean-square sense, provided that the number of discontinuities of the plant parameters is small, on average. Furthermore, in the case of partially unknown plant parameters, we show that the adaptive controller obtained by combining this control law with a suitable estimation algorithm, guarantees closed-loop boundedness and small tracking error in the mean-square sense, provided that, in addition, the functional dependence on time of the controller parameters is known up to a slowly time-varying component.

ISSN:0020-7179    

DOI:10.1080/00207179208934368

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A new applications-oriented approach—individual channel design (ICD)—to multivariable feedback control for 2-input 2-output systems was presented and justified in a series of papers (O'Reilly and Leithead 1991, Leithead and O'Reilly 1991 a, b, 1992 a). This paper is the first part of a two-part investigation into the extension of the ICD framework, and the performance issues thereof, to generalm-inputm-output systems. The main results of this first part are fourfold. First, the ICD framework for generalm-inputm-output systems is justified for all multivariable system structures (RHP poles and zeros). In particular, it is shown that ICD on the originalm-inputm-output cross-coupled multivariable system is valid irrespective of the degree of cross-coupling. Second, the influence of (individual transfer function, channel, transmission) right half-plane zeros on controller design and closed-loop channel performance is elucidated. Third, the existence of fixed stabilizing controllers for uncertainm-inputm-output systems is established. Fourth, it is shown how a separation of channel design tasks may be effected through invoking customer bandwidth specifications on different channels.

ISSN:0020-7179    

DOI:10.1080/00207179208934369

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This paper presents a simple and non-iterative procedure for the computation of the exact value of the infimum in the singularH∞-optimization problem, and is an extension of our earlier work. The problem formulation is general and does not place any restriction on the direct feedthrough terms between the control input and the controlled output variables, and between the disturbance input and the measurement output variables. Our method is applicable to a class of singularH∞-optimization problems for which the transfer functions from the control input to the controlled output and from the disturbance input to the measurement output have no invariant zeros on the jω axis and also satisfy certain geometric conditions. The computation of the infimum in our method involves solving two well-defined Riccati and two Lyapunov equations.

ISSN:0020-7179    

DOI:10.1080/00207179208934370

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

In this paper, a discontinuous control law is proposed that achieves simultaneous tracking for a group of decoupled linear single-input single-output systems. Application of the proposed control law to two robotic manipulators ( two-fingered robotic hand) is presented.

ISSN:0020-7179    

DOI:10.1080/00207179208934371

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The largest robust stability radiusγ(P0)of a systemP0is defined as the radius of the largest ballBmaxin the gap metric centred atP0which can be stabilized by one single controller. Any controller stabilizingBmaxis called an optimally robust controller ofP0. A controller, regarded as a system, should have its own largest robust stability radius also. In this note it is first shown that the largest robust stability radius of any optimally robust controller ofP0is larger than or equal to γ(Po)- The main result of this paper is the estimate of the variations (in the L∞-norm) of the closed-loop transfer matrix caused by the perturbations of the system or of the optimally robust controller. Finally, the schemes of designing finite-dimensional controllers are presented via the largest robust stability radius. These schemes guarantee that the designed finite-dimensional controllers will stabilize the original infinite-dimensional systems. Moreover, the closed-loop transfer matrices can be estimated.

ISSN:0020-7179    

DOI:10.1080/00207179208934372

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A new bias-compensating least squares (LS) method is presented for the parameter estimation of linear single-input single-output (SISO) continuous-time systems. A discrete-time model obtained by using the linear integral filter is augmented by introducing a pre-filter on the input and then the parameters of the augmented model are estimated by the conventional LS method. The distinct characteristic roots of the pre-filter are used to estimate the bias in the LS estimate. The pre-filter should be chosen so that its frequency bandwidth is wider than those of the system and the input signals. Since the new method requires minimal information on the noise characteristics, it is easily applicable to the case of coloured noise.

ISSN:0020-7179    

DOI:10.1080/00207179208934373

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

We propose a new approach to robust control of nonlinear systems. The approach is indirect in the sense that we will translate a robust control problem into an optimal control problem and apply optimal control methods to solve the robust control problem. We show that the method can be applied to nonlinear systems that satisfy the matching condition.

ISSN:0020-7179    

DOI:10.1080/00207179208934374

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor