MODEL VALIDATION IN ITERATIVE IDENTIFICATION AND CONTROLLER-DESIGN

The paper deals with the validation of model purposivity in iterative identification and controller design. It is known that when closed loo p requirements are too high, the model resulting from the iterative pr ocedure might conflict with the prior knowledge about the process. How ever, in some cases violated plausibility of the identified models doe s not necessarily imply its violated purposivity. Therefore, it is a m atter of practical relevance to have a confident indication of whether the given model will result in a stable closed loop design or not. If not, the iterative identification and controller design should be sto pped, i.e. more appropriate model structures should be chosen. In the paper a stochastic robustness measure is proposed which relies on the estimated model error obtainable by the stochastic embedding technique . In the simulated example we consider three models resulting from ite rative procedure that have different qualities regarding plausibility acid purposivity. It is shown that the stochastic robustness measure p rovides a reliable estimate of the designed loop stability. (C) 1998 I MACS/Elsevier Science B.V.