Design of fuzzy controllers based on frequency and transient characteristics

The authors propose design methods for fuzzy phase-lead compensators based on frequency and transient characteristics in fuzzy control systems. The main feature of these fuzzy phase-lead compensators is that they have parameters for effectively compensating phase characteristics in control systems. Two theorems based on the concept of frequency and transient characteristics are derived. One is a theorem for judging whether a fuzzy phase-lead compensator should be used or not. The other is a theorem for realizing phase-lead compensation. A method for designing a fuzzy phase-lead compensator for linear controlled objects is constructed using these theorems. The method is extended to unknown or nonlinear controlled objects. Simulation results show the validity of these design methods