Analysis and design of fuzzy controllers in frequency domain

This paper describes analysis and design of fuzzy phase-lead compensators in frequency domain. The main feature of fuzzy phase-lead compensators is to have parameters for effectively compensating phase characteristics in control systems. We show an important theorem, which realizes a phase-lead compensation, by introducing concept of frequency characteristics. Two design procedures of fuzzy phase-lead compensators are presented: cases of linear plant and unknown nonlinear plant. We apply one of the design procedures to tank level control which is a non linear system with dead time. Simulation results show validity of the design method