Performance analysis of fuzzy controller with delay

Fuzzy controller is wildly used in complex systems control as a kind of nonlinear controller based on human experience. The system often performances differently because of unexpected disturbance such as communication delay between the controller and the plant. This paper analyzes the performance of the fuzzy controller with delay by using the describing function method. Paper proposed the describing function for both Mamdani and Tagaki-Sugeno (T-S) type of fuzzy controller. The system stability and performance is analyzed by extend Nyquist plot generated by the describing function. Some examples are also given.