A Complete Tuning Procedure and Root Locus Stability Evaluation for Fuzzy Logic Control Systems

A complete tuning procedure of designing a fuzzy logic controller (FLC) and a new stability evaluation using root locus criterion for fuzzy dynamic systems are presented. The importance of FLC in industrial applications arises from the fact that a nonlin-ear mapping between inputs and outputs of the process that leads to a preferred controller performance which can be easily described by fuzzy linguistic variables and fuzzy rules. However, tuning a FLC based on trial-and-error basis is usually a tedious and time-consuming task. Stability issues of FLC systems still remain unknown as well. All of these bring over criticisms and attacks in fuzzy logic technology. In this paper , we developed a complete tuning guideline for FLC parameters (membership functions, scaling factors, rules) to simplify the tuning process. Moreover, we introduced a novel stability evaluation criterion for FLC systems based on root locus technique to design a stable fuzzy control system. Finally, simulation results also show that a fuzzy logic controller demonstrates superior outcomes to a conventional Proportional-Integral-Derivative (PID) controller in term of rise time and peak percent overshoot.