A tuning algorithm for the PID controller utilizing fuzzy theory

Abstract

In this paper, we proposed a new PID tuning algorithm by the fuzzy set theory to improve the performance of the PID controller. The new tuning algorithm for the PID controller has the initial value of parameter Kp, /spl tau//sub I/, /spl tau//sub D/, by the Ziegler-Nichols formula (1942) that uses the ultimate gain and ultimate period from a relay tuning experiment. We will get the error and the error rate of plant output corresponding to the initial value of parameter and find the new proportion gain (Kp) and the integral time (/spl tau//sub I/) from fuzzy tuner by the error and error rate of plant output as a membership function of fuzzy theory. This fuzzy auto tuning algorithm for PID controller considerably reduced the overshoot and rise time as compared to any other PID controller tuning algorithms. And in real parametric uncertainty systems, it constitutes an appreciable improvement of performance. The significant properties of this algorithm is shown by simulation.