Stability analysis of variable-structured PI controller by fuzzy logic for servo system

The authors propose a variable structure PI (proportional plus integral) controller whose structure is continuously varied by fuzzy logic such that a proportional controller dominates the integral controller if the absolute value of the error is large and vice versa in order to obtain a high-performance controller (with quick time response and without overshoot). Then it is applied to servo motor speed control. The global and asymptotic stability of the overall control system is proved by using the Lyapunov stability theorem.<
>