Design of Fuzzy PD+I Controller Based on PID Controller

Oh, Sea-June; Yoo, Heui-Han; Lee, Yun-Hyung; So, Myung-Ok

Journal of Navigation and Port Research 2010;34(2):117-122.
Published online March 30, 2010.

Design of Fuzzy PD+I Controller Based on PID Controller

Sea-June Oh, Heui-Han Yoo, Yun-Hyung Lee, Myung-Ok So

Abstract

Since fuzzy controllers are nonlinear, it is more difficult to set the controller gains and to analyse the stability compared to conventional PID controllers. This paper proposes a fuzzy PD+I controller for tracking control which uses a linear fuzzy inference(product-sum-gravity) method based on a conventional linear PID controller. In this scheme the fuzzy PD+I controller works similar to the control performance as the linear PD plus I(PD+I) controller. Thus it is possible to analyse and design an fuzzy PD+I controller for given systems based on a linear fuzzy PD controller. The scaling factors tuning scheme, another topic of fuzzy controller design procedure, is also introduced in order to fine performance of the fuzzy PD+I controller. The scaling factors are adjusted by a real-coded genetic algorithm(RCGA) in off-line. The simulation results show the effectiveness of the proposed fuzzy PD+I controller for tracking control problems by comparing with the conventional PID controllers.

Key Words: fuzzy PD+I controller;scaling factors;tracking control;product-sum-gravity method;RCGA