Design of a GA-based fuzzy PID controller for non-minimum phase systems

In this paper, a fuzzy PID controller, is investigated on the basis of genetic algorithms (GAs) to eliminate the undershoot of a nonminimum-phase (NMP) system and to improve the transient response at the same time. The proposed controller employs a two-stage control structure, where the fuzzy PI controller is reasonably used to cancel out the effect of unstable zeros and the fuzzy PD controller is introduced for the reason of reducing the overshoot. The fuzzy control rules for both controllers are evolved and determined by the GAs. It is demonstrated by computer simulations in which satisfactory performance can be achieved even if the system is under perturbed conditions.