City Research Online

Abstract

Accurate models of complex systems are, of necessity of a higher order. It is often convenient to use a simpler model when investigating characteristics Of such a system. For this purpose a method of model reduction is required. Much work has been carried out in recent years on model reduction techniques. A comprehensive survey of these has been carried out and is presented here.

The reviewed works do not deal with first order plus time delay models which can in certain cases be used for controller design. For this purpose the simple model must be less stable than the system itself. Many models do not fulfil this requirement. An investigation into the adequacy of first order plus time delay models obtained using the Pade technique has been carried out and its findings are given in section 3.

Finally an examination is carried out into the performance of closed loop systems using controllers obtained from first order plus time delay models. It is shown that adequate Pade models can be used to give suitable controllers and that if no adequate Pade model exists then an alternative method can be used to give acceptable results.

Publication Type:	Thesis (Doctoral)
Subjects:	Q Science Q Science > QA Mathematics > QA75 Electronic computers. Computer science
Departments:	School of Science & Technology School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

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