A SIMPLE METHOD FOR TUNING CASCADE CONTROL-SYSTEMS

A simple method for tuning controllers in a cascade system is presente d. In this method, all the relations that facilitate the tuning proced ures are well prepared in terms of figures or simple equations. Using these figures and equations, the controller tuning for different confi gurations of cascade systems becomes easy and straightforward when pro cess models are available. On the other hand, when process models are not available, a simple method that uses one single run of step input experiment to develop such models is proposed. Based on these developm ents in the controller tuning and process models, an autotuning system that uses relay feedback is presented. Unlike the existing autotuning systems, this proposed system conducts identification and controller tuning in a decoupled manner. As a result, no excessive trial-and-erro r efforts for modeling, and tuning are required. Simulation results sh ow the potential usage of such a method. It is interested to see that the resulting systems have almost compatible responses to those system s which have been designed optimally in one way or another as reported in the literature. It is not, however, the purpose of this article to emphasize on obtaining superior performance to all other existing met hods, but to emphasize on its effectiveness and simplicity for applica tion.