摘要:

A paper by Bode has shown the limitations of using a feedback structure in terms of an integral constraint on the sensitivity function for open-loop stable continuous-time systems. The paper by Mohtadi examines and derives equivalent results for discrete-time feedback systems. These integral constraints also provide some guidelines regarding the philosophy of feedback design specifically for sampled-data systems. For example, it is shown that, for all sampled-data control systems, there is a maximum sampling frequency, beyond which little improvement in performance is gained.

DOI:10.1049/ip-d.1990.0006

出版商:IEE    

年代:1990

数据来源: IET

摘要:

Outlier-contaminated normal errors in regression problems are modelled by exponential power distributions and the resulting maximum likelihood estimators are shown to involveLpminimisations (1 <p≤ 2). It is shown thatL1 +estimation is minimax outlier-robust and minimax covariance-robust over the neighbourhood of exponential power distributions. Efficiency loss is negligible. Recursive gradient-typeLpestimators are derived and shown to be convergent and consistent. The major limitation on outlier robustness is seen to be the requirement for convergence of the recursive minimisation. The algorithm is validated with an application in adaptive control.

DOI:10.1049/ip-d.1990.0007

出版商:IEE    

年代:1990

数据来源: IET

摘要:

A method is proposed for calculating the input map of a stable linear dynamic system directly from its impulse response matrix. Several canonic forms are proposed for these maps, and their properties are developed. These canonic forms are used to provide methods for determining a system realisation and its corresponding Gramians. This approach is applied to the calculation of a balanced realisation.

DOI:10.1049/ip-d.1990.0008

出版商:IEE    

年代:1990

数据来源: IET

摘要:

The paper presents a systematic study using piecewise-constant orthogonal functions for the analysis of impulsive responses of singular systems.

DOI:10.1049/ip-d.1990.0009

出版商:IEE    

年代:1990

数据来源: IET

摘要:

The transfer-function identification method described in the paper is based on the use of the modulating function technique with measured crosscorrelation and autocorrelation functions. Errors introduced by the use of low-order models and variance of measured correlation functions are investigated.

DOI:10.1049/ip-d.1990.0010

出版商:IEE    

年代:1990

数据来源: IET

摘要:

An algorithm is proposed for characteristic polynomial assignment via state feedback for a wide class of two-dimensional discrete systems. For this class of systems, the required feedback vector is given analytically.

DOI:10.1049/ip-d.1990.0011

出版商:IEE    

年代:1990

数据来源: IET

摘要:

Band-limiting filters can be employed to monitor the propagation of signals, originating as external inputs of known structure, through dynamic systems. By generating and comparing band-limited signals at different points in a control system, faults in system behaviour may be detected. Earlier work has described the use of this technique for fault detection in complete closed-loop systems, and, in the paper, a similar approach is applied to monitoring hardware or software faults in a control computer.

DOI:10.1049/ip-d.1990.0012

出版商:IEE    

年代:1990

数据来源: IET

摘要:

A frequency-domain approach to the absolute stability analysis of multivariable time-invariant discrete-time linear quadratic regulators is developed in the paper. An imbedding form of a fundamental equality relating the return-difference and the open-loop transfer matrices is the key for the application of the Popov criterion in the analysis. This imbedding form also establishes a necessary condition for a closed-loop matrixtransfer function to have been obtained through an LQ design.

DOI:10.1049/ip-d.1990.0013

出版商:IEE    

年代:1990

数据来源: IET

摘要:

An improved method of robust adaptive control is developed in the discrete-time form using the Euler operator and is applied to the positioning control of an electrohydraulic servosystem. The number of parametersto be identified is reduced by using the knowledge of plant model structure and carrying out the design procedure for model reference control, treating the plant parameters as unknown coefficients. It was found from the experiments that the proposed method reduces the computation time significantly, compared with the method used in an earlier work, while maintaining the same control performance.

DOI:10.1049/ip-d.1990.0014

出版商:IEE    

年代:1990

数据来源: IET