Stability Analysis of a Fuzzy Control System
Thananchai Leephakpreeda, Celal Batur · 1997
Fuzzy controllers are now widely used as intelligent controllers in industrial applications. Intelligent control is understood in the sense that these controllers mimic an experienced human operator. To enhance the robustness ofthe fuzzy controller, the stability ofthe fuzzy bontrol system needs to be analyzed. In the stability analysis, the fuzzy controller is replaced with an appropriate describing function which represents the nominal model of the fuzzy controller. The Nyquist stability crit.:ria is then performed to determine thc stability of the fvzzy control system. Additionally, this analysis can predict the existence of the limit oscillation. The simulation results have shown that the presented methodology can be used to analyze the stability of a fuzry feedback control system and predict the limit cycle. A class of a fuzzy control system is illustrated in Figure L Generally, a set of fuzzy control rules implemented by the fuzzy controller can be