Discrete-Time Fuzzy PID Control

Abstract

In this study, a parallel structure of fuzzy PID control systems is presented. It is associated with a new tuning method which, based on gain margin and phase margin specifications, determines the parameters of the fuzzy PID controller. In comparison with conventional PID controllers, the presented fuzzy PID controller shows higher control gains when system states are away from equilibrium and, at the same time, retains lower profile of control signals. Consequently better control performance is achieved. With the presented formula, the weighting factors of a fuzzy logic controller can be systematically selected according to the plant under control. By virtue of using the simplest structure of fuzzy logic control, the stability of the nonlinear control system is able to be analyzed and a sufficient BIBO stability condition is given. The superior performance of the controller is demonstrated through both numerical and experimental examples.