摘要:

The problem of optimal robust tracking in two-parameter adaptive control systems under non-linear time-varying unmodelled dynamics is examined. A new robust stability criterion is derived for analysing the robustness of adaptive control systems with non-linear time-varying model errors. Based on the concept of excess robustness and the theory of the minimum H∞norm, a simple and feasible design algorithm is presented to synthesize a two-parameter adaptive controller which ensures that adaptive control systems can achieve the object of optimal robust tracking in the presence of non-linear time-varying unmodelled dynamics. Simulation results that demonstrate features of the two-parameter adaptive controller with optimal robust tracking in the light of the design algorithm are included.

ISSN:0020-7721    

DOI:10.1080/00207729008910452

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Some critical computations in pole-placement design and in that of many model reference adaptive systems are described. These numerical problems are associated with the resolution of the diophantine equation. They occur when the assumption of no common poles and zeros is violated. Regularization techniques which cope with ill-conditioning are presented. The resulting algorithm combines a standard indirect pole-placement adaptive control algorithm and a dimension-free regularization procedure of the design equations, thus avoiding the pole-zero cancellation problem and yet retaining the other properties of the algorithm. The application of this control scheme in a pulsed liquid-liquid extraction column is described. The control objective is to optimize the column behaviour. Extraction columns are subject to changes in feed compositions, feed flow-rates, physical properties of the solvent (the extractor) and the solute (liquid mixture) and various disturbances. The column exhibits highly non-linear and time-varying dynamics. The conductivity measured at a specific place in the column and the pulse frequency have been selected as control variables. Experimental results demonstrate the usefulness and the robustness of this regularized pole-placement adaptive control algorithm.

ISSN:0020-7721    

DOI:10.1080/00207729008910453

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Optimization methods for reliability systems on diversified criteria for varied types of models are being increasingly developed. Venugopal et at. (1986–1989) have initiated notable lines of work in this direction for a large class of reliability models considering some comprehensive types of cost functions. This paper adds to this work in terms of considering the complex models, namely the series–parallel reliability system. A methodology is developed with the help of an algorithm to obtain cost-space optimal systems in a class of series parallel models based on practical cost considerations. The operational use of the theoretical work is brought out through some empirical results. A qualitative analysis is also provided as a useful companion study.

ISSN:0020-7721    

DOI:10.1080/00207729008910454

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Several simultaneous eigenvalue bounds for the solution of the differential and difference Lyapunov equations are presented. It is shown that, in certain cases, each bound is obtained as a solution of a simple scalar differential or difference equation. In the limiting case where the solution to the differential or the difference Lyapunov equation becomes stationary, some of the results reduce to several existing bounds for the algebraic equations.

ISSN:0020-7721    

DOI:10.1080/00207729008910455

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A systematic method based on the pole placement approach is proposed to design non-square multivariable internal model control systems. The control law is a kind of the classical IMC controller for square MIMO systems, but process model factorization and inversion are combined into the derivation of the approach. The control law can be extended to handle any minimum or non-minimum phase n input and m output systems. The absolute value of the implemented tuning parameters is restricted to (0,1) to guarantee internal stability of the control system. If all the parameters are set equal to one, the resulting closed-loop responses follow the conservative behaviour in simplified model predictive control. Alternatively, if the parameters are shrunk to zero, the proposed control law becomes multivariable deadbeat control.

ISSN:0020-7721    

DOI:10.1080/00207729008910456

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

In this paper we develop a general approximation framework for use in optimal control problems governed by non-linear differential equations by means of a block pulse operator. In the approximation framework, the convergence in the mean square of the block pulse series (BPS) solutions to the optimal control problem is proved, and first-order convergence in the U2-metric is established. We also prove that the BPS solutions of state variables converge uniformly to the exact solution of the optimal state. Computational examples are presented to illustrate the utility of this method.

ISSN:0020-7721    

DOI:10.1080/00207729008910457

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The analysis of parallel systems with two dissimilar units is examined. Each unit has two modes—‘normal’ or ‘total failure’. Whenever an operative unit fails, an administrative delay occurs in locating the repairman and making him available at the system location. A system is observed at suitable regenerative epochs in order to obtain various economic related reliability characteristics. The explicit results are obtained in few particular cases.

ISSN:0020-7721    

DOI:10.1080/00207729008910458

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Recently an algorithm was developed by Lefas et at. (1988), for estimating the absolute altitude of civil aircraft using measurements from two sets of distance measuring equipment (DME). An interesting conclusion was that if the aeroplane deviates from the airlane marked by the two DMEs, secondary surveillance radar (SSR) measurements are also necessary, and this fact causes the degradation of the filter's performance. The present paper investigates the use of three DMEs for the estimation of the aircraft's absolute altitude, in which case no SSR is needed. The DME measurements are processed on-board using a first-order Kalman filter and an accuracy of 30 ft is achieved with normal DMEs and a sampling interval of 01 s.

ISSN:0020-7721    

DOI:10.1080/00207729008910459

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Two algorithms for solving the piecewise linear least–squares approximation problem of plane curves are presented. The first is for the case when theL2residual (error) norm in any segment is not to exceed a pre–assigned value. The second algorithm is for the case when the number of segments is given and a (balanced)L2residual norm solution is required. The given curve is first digitized and either algorithm is then applied to the discrete points. For each segment, we obtain the upper triangular matrixRin theQRfactorization of the (augmented) coefficient matrix of the resulting system of linear equations. The least–squares solutions are calculated in terms of theR(andQ) matrices. The algorithms then work in an iterative manner by updating the least–squares solutions for the segments via up dating theRmatrices. The calculation requires as little computational effort as possible. Numerical results and comments are given. This, in a way, is a tutorial paper.

ISSN:0020-7721    

DOI:10.1080/00207729008910460

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The paper suggests an unconventional concept, ‘partial conservativity’. Oscillator models (three-phase oscillators of a certain type are chosen here to demonstrate the concept) which exemplify the property of partial conservativity are discussed. These models are also suggested for developing practical systems where an interfering bias level is avoided.

ISSN:0020-7721    

DOI:10.1080/00207729008910461

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor