Using Fuzzy Logic in Control Applications: Beyond Fuzzy PID Control - IEEE Control Systems Magazine

substantial portion of the literature on fuzzy control deals with the use of fuzzy rules to implement nonlinear proportional-integral-derivative (PID) type control. As a result, many control engineers are led to believe that using fuzzy rules to implement nonlinear PID control is the prime use of fuzzy logic for control. However, when we examine commercial products in which fuzzy control is said to be incorporated, we rarely see fuzzy logic being used to implement nonlinear PID (proportional-integral-derivative) control; fuzzy logic is used mostly to handle high-level control functions that traditional control methods do not address. This article discusses different ways that fuzzy logic can be used in high-level control functions. Specifically, we examine the use of fuzzy logic for supervisory control, for selecting discrete control actions, for identifying the operating environment, and for evaluating controller performance. The purpose of this article is to stimulate the use of fuzzy logic to provide new control functions that are outs ide the domain of t rad i t iona l control-where fuzzy control is likely to provide the greatest payoff.