摘要:

A survey of the literature in which Liapunov's second method is used in determining the control Jaw is presented, with emphasis placed on the model-tracking adaptive control problem. Forty references are listed. Following a brief tutorial exposition of the adaptive control problem, the techniques for treating reduction of order, disturbance and time-varying parameters, multivariate systems, identification, and adaptive observers are discussed. The method is critically evaluated, particularly with respect to possibilities for application.

ISSN:0020-7179    

DOI:10.1080/00207177308932569

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

A geometrical technique is developed by which different methods of sampling the state of a one-dimensional distributed system may be related. Using this approach, transformations are derived relating scanned sampling to continuous time, discrete spatial sampling and to space distributed time sampling. Utilization of the technique is demonstrated in the derivation of stability relations for the case of a statically unstable string that is to be made stable by a scanned detector and controller. Of possible practical significance is the observation that scanned sampling can provide many of the characteristics of a spatially distributed sensor or controller, especially if the scan period is short. A limitation, which arises from the imposition of causality on real systems, is observed in the example.

ISSN:0020-7179    

DOI:10.1080/00207177308932570

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

The effect of inherent finite delay which is not an integral multiple of the sampling period on the character of limit cycles in a second-order feedback control system with a relay type non-linearity is analysed. It is found that the addition of transportation log alters the character of the modes sustained by the system. All the modes that can be sustained for each fractional value of the delay which lies between zero and one and two and three sampling periods are determined by the discrete describing function method. In this connection the critical regions developed by the authors for periods ranging from 9Tto 20Thave been found to be very useful. The different sots of initial conditions which give rise to the various modes are also established via the state transition technique. It is observed that an increase in the transportation lag usually results in an increase in the amplitude as well as the period of oscillation. Square-wave dither is found to produce a large steady-state error for a step input. The larger the value of the delay, the larger the amplitude of dither signal required to quench the limit cycle. Furthermore, it is noticed that when the dither signal is unable to quench the limit cycle, it sometimes alters either the period or the amplitude of oscillation.

ISSN:0020-7179    

DOI:10.1080/00207177308932571

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

The well-known concept of frequency response is extended to that of a discrete-time type and the identification method is proposed which uses a sinusoidal test signal of discrete-time type. The proposed method is easily implemented by a digital computer. The identification is performed sequentially in time. It is only required to estimate the corresponding response to a composite signal ofn-distinct frequencies and so the identification time is much reduced.

ISSN:0020-7179    

DOI:10.1080/00207177308932572

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

The paper discusses a versatile family of Monte Carlo methods for the sequential optimization of stochastic systems. The method selects a sequence of successive one-dimensional search directions, defines a (stochastic) search in each of the directions, where the data used for both the one-dimensional search and the direction determination are merely noise-corrupted observations on the system. The method is more general than stochastic approximation, it converges to a stationary point even in the presence of multiple minima, and it uses rather natural logics. A convergence theorem is proved.

ISSN:0020-7179    

DOI:10.1080/00207177308932573

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Two lesser-known classical elimination techniques are applied in matrix form to the linear system stability problem of determining when the roots of a realnth degree polynomial all have negative real parts. In particular, for calculation of the critical Hurwitz determinant Δn−1a new tabular scheme is obtained which is superior to the Routh array for parametric stability problems. An extension leads to new half-order expressions for the other ΔtAnother reduction of Δ−1in terms of minors of order about ¼n is also given.

ISSN:0020-7179    

DOI:10.1080/00207177308932574

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Given a linear time-invariant controllable and observable multivariable system ẋ=Aˆ+Bˆu, y=Cˆswithminputs andpoutputs, it is possible to assign max (m,p) poles of the system (Davison 1970, Davison and Chatterjee 1971) arbitrarily close to desired locations using constant gain output feedback. This paper provides a new proof of Davison's theorem on pole-placement and leads to a design procedure which has certain advantages over Davison's method. In some cases, more than max (m, p) poles can be assigned arbitrarily. Assuming the system is output stabilizable, a least square design technique is outlined to approximate the desired pole locations when it is not possible to place all the poles.

ISSN:0020-7179    

DOI:10.1080/00207177308932575

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Difficulty is often encountered in stability analysis in the construction of Liapunov functions for systems. Also Liapunov' theorems often only ensure stability when asymptotic stability is required when [Vdot](X) is semi-definite. The theorem presented enables asymptotic stability information to be obtained when [Vdot](X) is semi-definite in regions of state space where other theorems only ensure stability.

ISSN:0020-7179    

DOI:10.1080/00207177308932576

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

This paper considers a non-conservative pendulum-type non-linear oscillator which emulates some behavioural features of systems displaying adaptive response, or biological rhythms, under the influence of an environmental excitation (‘ Zeitgeber ’) of electromagnetic origin, for instance. Of special interest are : (a) The entraining or locking-in process of the oscillation under a sudden change Δω of the Zeitgeber frequency ; (b) the time interval within which locking-in is achieved, and (c) the evolution of the oscillation under constant excitation of varying amplitude

ISSN:0020-7179    

DOI:10.1080/00207177308932577

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Non-linearities affect process identification and linear testing techniques should not be used unless it has been shown that the process is substantially linear within the range of the test signals. A technique is presented which allows extensions of linear identification procedures to be used to identify open-loop processes which contain single-valued non-linearities. It is shown how the effects of the non-linearities may be removed from the output signal, thus allowing identification of the linear dynamics from deterministic signal tests and by random signal cross-correlation techniques. The technique also admits of the determination of that part of the output signal attributable to each power of non-linearity which, in the case of random signal testing, allows the multidimensional impulse responses of the system to be determined independent of the power level of the test signal. It is also shown that, by suitable choice of parameters, the error in the result owing to noise can be made to be no greater than that in the equivalent linear technique.

ISSN:0020-7179    

DOI:10.1080/00207177308932578

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor