Fractional Order Fuzzy PID Controller for a Rotary Servo System

Abstract

This paper proposes a fractional order fuzzy PID controller(FOFPID) for a rotary servo system. The controller part consists of the summation of fractional integral of error and output of fuzzy logic controller which has two inputs, that are error and fractional derivative of error. The fractional order differentiation and error in the fuzzy logic controller (FLC) are kept as input scaling factors and are streamlined with fuzzy inference system (FIS) to limit integral error indices along with the control signal as the goal work. The performance of the controller for closed loop state is compared with typical PID and fractional order PID controller(FOPID). The performance of the designed controller is measured by evaluating different parameters like peak overshoot, settling time and rise time. Stability of the designed controller is evaluated by integral absolute error and integral time absolute error. Step response to each case shows the improved performance of FOFPID controller over typical PID controller and FOPID controller.