摘要:

An investigation is made of the stability for the discrete control of drives using a frequency induction motor as an actuator. The approach proposed is based on the choice of a particular model of the discretized system which is non-linear in the state and linear in the control. Because the model parameters depend only on the value of the slip angular frequency, the stabilizing control law is obtained by considering the non-linear time-invariant system as a linear time-varying one. As a consequence, the feedback control is a linear function of the state variables with coefficients depending on the actual values of the time-varying system parameters. The difficulty for computing these coefficients in line is overcome by proposing a suitable choice of constant feedback coefficients, which, for the case of the induction motor, give very efficient and satisfactory results.

ISSN:0020-7721    

DOI:10.1080/00207729008910495

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A control system design is presented for large angle rotational manoeuvres of a spacecraft-beam-tip body (an antenna or a reflector) configuration. Although this approach is applicable to three-axis manoeuvres, for simplicity only single-axis control is treated here. It is assumed that an unknown but bounded disturbance torque acts on the spacecraft. A sliding mode attitude control law is derived for slewing of the space vehicle. This slewing control law requires only the attitude error and its derivative for feedback. It does not need any information on the elastic motion of the system. For the damping of the elastic motion, a stabilizer is seperately designed based on the asymptotically decoupled system describing the elastic deflections in two orthogonal planes. Simulation results are presented to show that precise large rotational manoeuvres can be performed using an attitude controller and elastic mode stabilizer in spite of the uncertainty in the system.

ISSN:0020-7721    

DOI:10.1080/00207729008910496

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The problem of employing linguistic variables to rank alternatives across a set of criteria is investigated, with emphasis placed on modelling the decision-maker's reasoning process. Given a set of alternatives, decision-makers often do not make conclusions immediately, instead evaluating them in the light of a given set of criteria and then synthesizing the knowledge obtained from the evaluation. Both evaluation and synthesis are usually expressed linguistically rather than numerically. A fuzzy mathematical model is employed to represent this sort of linguistic evaluation and synthesis. An example is presented to illustrate the basic idea and technique. This example is also used to compare the proposed technique with another existing technique. The model can be employed in expert systems for making inferences on multi-criteria problems.

ISSN:0020-7721    

DOI:10.1080/00207729008910497

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The solution of a linear two-point boundary value problem with time-varying coefficients is obtained by Fourier series approximation. Properties of Fourier series are first briefly discussed and the operational matrix of integration is presented. A transformation matrix relating the back vector to the current time vector together with the operational matrix are utilized to reduce the system to a set of linear algebraic equations and thereby obtain the approximate solution. Illustrative examples are included to demonstrate the validity and applicability of the technique.

ISSN:0020-7721    

DOI:10.1080/00207729008910498

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

This paper presents one of the very important applications of the multimodel con-trot technique. This type of control enables us to extend the use of linear control theory to applications in non-linear complex processes. The process under control is modelled by several linear models around different points and modes of operation. During the application, the right model is selected among the available set of models and is used to generate suitable control signals which enable the process to track certain desired trajectories. This controller is built by the use of a microcomputer interfaced with a non-linear thermal process where the inside temperature and humidity are the controlled variables. The results of a real-time application to this process are given.

ISSN:0020-7721    

DOI:10.1080/00207729008910499

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The approximation of a Hankel matrix by finite rank Hankel matrices is considered. A constructive procedure is proposed for the approximate realization of a linear analytic system by means of bilinear systems.

ISSN:0020-7721    

DOI:10.1080/00207729008910500

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Lyapunov-type equations for matrix root-clustering in a transformable subregion of the complex plane have been developed. The matrix equations are given in terms of functions of Kronecker products or bialternate products. Illustrative examples are included.

ISSN:0020-7721    

DOI:10.1080/00207729008910501

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A new approach with three novel operations is proposed to deal with analysis of linear and bilinear time-varying systems and optimal control of linear time-varying systems via the Taylor series. The use of the three operations: polynomial mapping, general multiplication and integral transformer can greatly simplify the algorithm derivations and computations. Recursive algorithms are obtained and several illustrative examples are given.

ISSN:0020-7721    

DOI:10.1080/00207729008910502

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Sufficient conditions are obtained for the asymptotic stability of the trivial solution of

ISSN:0020-7721    

DOI:10.1080/00207729008910503

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

In this paper we develop a parameter estimation procedure for a stochastic process when that process is non-stationary. Although the estimation procedure itself is very general, we derive the model for the particular case of a Poisson process with parameter µ(t) subject to exponential decay. We then illustrate the application of this particular model to a fundamental problem in the management of inventories subject to obsolescence, i.e. how to identify excess inventories in sufficient time to ensure that stocks are cleared before the end of the season.

ISSN:0020-7721    

DOI:10.1080/00207729008910504

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor