Design of Self-Tuning Fuzzy Logic Controller

During the past several years fuzzy control has emerged as one of the most active and fruitful areas of research in the field of control engineering especially, in the realm of industrial processes. Fuzzy control, based on fuzzy logic is a logical system which incorporates human thinking rather than traditional analytical methods. Therefore, this paper aims to explore the utility of this control strategy by developing a simple self-tuning scheme for a Fuzzy Logic Controller (FLC). Here, the input gains viz. GE (proportional error gain) and GDE (derivative error gain), are adjusted on-line by fuzzy rules according to the current trend of the controlled process. The rule base for tuning the input gains is defined on error (E) and rate of change of error (DE) of the controlled variable. This self-tuning scheme is implemented on a pressure process, and it’s performance is compared with a PID controller and a conventional FLC in terms of time domain measures such as rise time, % overshoot, settling time and % steady state error. The self-tuning scheme shows improved performance in terms of zero percentage overshoot. Copyright © 2015 IFSA Publishing, S. L.