Fuzzy CAD for variable structure PI(D) controller

A novel robust PI (proportional and integral) controller including differential action is devised. The algorithm is derived on the basis of variable structure system theories. The controller stability is examined by using the Lyapunov stability theory. A simple fuzzy expert system which is a real-time CAD (computer-aided design) system is introduced. Initial controller parameters are interactively determined by using the fuzzy CAD. The proposed CAD is much simpler due to the introduction of the robust variable structure PI(D) controller rather than a conventional CAD for a PID (proportional-integral-derivative) controller, since it is not required to make much effort in parameter identifications