摘要:

The approximation of a distributed system by a lumped system using both exact analysis and qualitative reasoning is studied in some detail for the losslessLCtransmission line, and with much less detail for anRCline, a towed cable, and a deep-sea mining hauling pipe. We delimit, at least partly, the region of validity of the approximation, especially in analysing controllability questions. We also suggest why a form of nonuniform lumping may be more appropriate for the towed cable and the deep-sea mining hauling pipe.

DOI:10.1049/ip-d.1985.0017

出版商:IEE    

年代:1985

数据来源: IET

摘要:

Formulas which replace multiplication and division of polynomials by equivalent matrix operations are derived. The expressions not only simplify the computational process but can also be used in those fields where formal manipulations with polynomials are needed. Some applications in computer arithmetic are also mentioned.

DOI:10.1049/ip-d.1985.0018

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The CARMA model generally assumed in self-tuning control frequently leads to an offset between the measurement and the desired value when regulating a plant subjected to constant load disturbances about a nonzero set point. The normalad hocinsertion of an integrator solves the problem but can introduce others (such as convergence difficulties). The solution explored in this paper is to use a CARIMA plant model in which the noise term is nonstationary, and it is shown that good adaptive behaviour is then possible both with generalised minimum-variance and pole-placement self-tuning controllers. The approach produces integral control terms in a natural way, and, for simplified plant models, leads directly to a general PID algorithm.

DOI:10.1049/ip-d.1985.0019

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The problem of state-space model reduction and, in particular, the identification of essential states is considered. The method of a state/output energy index is reviewed and shown, in some cases, to yield insufficient information to determine the essential states. The modal indices of Litz are reassessed, exposing their explicit link with controllability. A new method of essential-state selection is proposed. First the dominant modes are identified, and then these are used to indicate which states contain a significant contribution from these dominant modes. The algorithm can be used to select the essential states in either the state vector or the output. The method is demonstrated on a model having the structure of a rolling mill stand model.

DOI:10.1049/ip-d.1985.0020

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The problem of numerically solving delay-differential equations is considered. The method proposed uses a Runge-Kutta method extended so that it is applicable to our delay case.

DOI:10.1049/ip-d.1985.0021

出版商:IEE    

年代:1985

数据来源: IET

摘要:

A heuristic method is proposed to overcome the divergence problems of the minimum variance state and parameter estimator. The algorithm uses adaptive, exponential fading. Rapid fading occurs when data give a poor fit with the model, and slow fading occurs when the data give a good fit. Subject to an observability condition, the estimator is shown to yieldN-step exponential convergence. The usefulness of the algorithm is demonstrated through one extended Kalman filter application. The algorithm has also been applied to industrial processes for state estimation and adaptive control.

DOI:10.1049/ip-d.1985.0022

出版商:IEE    

年代:1985

数据来源: IET