A PID-type fuzzy controller and its parameters tuning method

A kind of simple and practical fuzzy PID controller was constructed, and its mathematics expression was given. This fuzzy controller was composed of a linear item and a nonlinear modified item, the nonlinear item depended on all parameters of the fuzzy controller and modified ideally and dynamically the linear item. Based on the gain margin and phase margin principle, a pair of gain margin and phase margin was given as the closed-loop performance specification, the tuning formulas of the fuzzy controller were proposed and its parameters tuning problem was resolved. Finally, the simulation results prove that the fuzzy controller and its tuning method are feasible.