摘要:

The authors discuss the application of expert systems programming techniques to the design of lead-lag compensators for a linear, single-input/single-output, continuous-time plant. A design method based on first adjusting the high-frequency response with lead and constant-gain compensators followed by adjusting the low-frequency response with lag compensators has been developed. This design heuristic is presented and its ability to achieve specifications for a range of different plants is discussed. The heuristic has been implemented using the production rule knowledge representation; examples of production rules are given and their use is discussed. Inference-engine capabilities and extensions to a conventional analysis and design package, required to implement this automatic control system design method, are also outlined.

DOI:10.1049/ip-d.1987.0023

出版商:IEE    

年代:1987

数据来源: IET

摘要:

The paper presents a model reference adaptive control (MRAC) design which maintains stability around the equilibrium of the tracking error in the presence of unmodelled dynamics. Only a slighta prioriknowledge in terms of lower and upper bounds for the absolute values of the parameters and orders of the unmodelled dynamics is required. The key to achieving signal boundedness is to use an additional parameter in the adaptive controller which involves the use of thea prioriknowledge concerning the unmodelled dynamics.

DOI:10.1049/ip-d.1987.0024

出版商:IEE    

年代:1987

数据来源: IET

摘要:

The use of finite weighting sequence models to describe the behaviour of dynamic systems is particularly helpful when attempting to characterise the frequency-response uncertainty introduced by the model identification process. However, existing model selection criteria are not well suited for the identification of an appropriate level of truncation, nor do they attempt to identify the errors introduced by the specified truncation. The paper develops a new model-order selection criterion that will establish a statistically optimal truncation level and, simultaneously, quantify the frequency-response bias introduced by this truncation. In addition, modifications of the criterion are proposed to refine the frequency-response bias information at selected frequencies. The resulting bias information is then combined with earlier results, to establish a complete and quantitative description of frequency-response uncertainty.

DOI:10.1049/ip-d.1987.0025

出版商:IEE    

年代:1987

数据来源: IET

摘要:

An estimation technique for inferring infrequently measured process outputs, using other more rapidly sampled secondary outputs, is proposed. The estimator has a general structure and its parameters can be estimated online. In contrast to other estimation techniques in the literature, the proposed adaptive method requires minimal design effort and does not result in static estimation error. The problem of secondary output selection is therefore alleviated. Moreover, the estimator can track slow variations in both process and disturbance characteristics. Control schemes using the estimated values of the output are shown to yield considerably better performance than corresponding schemes which employ infrequently sampled values of the primary output.

DOI:10.1049/ip-d.1987.0026

出版商:IEE    

年代:1987

数据来源: IET

摘要:

The operational matrix of differentiation is used for the parameter identificaton of a class of time-varying linear systems using polynomial series. The main advantage of this approach is that it does not require the introduction of the initial conditions of the system, as it becomes necessary with the use of the operational matrix of integration. In this way the resulting algorithm is considerably simpler. The operational matrix of a polynomial series transformation is also used and may transform a given orthogonal polynomial series into another. This matrix simplifies considerably the computation of the product and coefficient matrices required for the identification of time-varying systems. Several characteristic examples are considered for the illustration of the effectiveness of the method.

DOI:10.1049/ip-d.1987.0027

出版商:IEE    

年代:1987

数据来源: IET

摘要:

Long-range predictive control appears to be a better foundation for self-tuning compared withk-step ahead or model-reference approaches. Various methods have been proposed in the literature based on weighting-sequence models, and the paper unifies their development. By assuming a noise structure which involves Brownian motion, natural integrating action is achieved as opposed to thead hocapproaches previously used. Simulation studies using truncated models show that large numbers of parameters are necessary using weighting sequences, although a parallel method using a CARIMA model is entirely satisfactory. When used with nonminimum-phase plant, the dynamic matrix control method works best.

DOI:10.1049/ip-d.1987.0028

出版商:IEE    

年代:1987

数据来源: IET

摘要:

The paper summarises a recent investigation to find out what contribution could be made to pH regulation by modern algorithms for online estimation and/or adaptive control. Topics discussed include a mathematical model to account for nonlinearity; full-scale trials using selftuning controllers; a specially developed nonlinear estimator; use of resulting estimates to drive a suboptimal ‘cautious’ control law; and a specialpurpose CAD package. It is concluded that pH regulation is amenable to good engineering practice, and that whether or not this should include modern algorithms is a problem-specific question which can be answered using the CAD package.

DOI:10.1049/ip-d.1987.0029

出版商:IEE    

年代:1987

数据来源: IET

摘要:

An improved algorithm is derived for obtaining and maintaining the correct optimal steady-stateoperation of an industrial process, inspite of deficiencies in the mathematical model employed within the optimisation procedure. An augmented Lagrangian technique is employed to extend a previous method which iterates between successive solutions of parameter estimation and modified system optimisation. Optimality and convergence conditions are given, and the paper includes a detailed proof of convergence based on Zangwill's approach. The practical utility of the algorithm is demonstrated on a pilot-scale chemical vaporiser plant, where its performance is compared with previous methods.

DOI:10.1049/ip-d.1987.0030

出版商:IEE    

年代:1987

数据来源: IET