Design of stable fuzzy-logic-controlled feedback systems

When fuzzy logic is used in feedback control, the consequence is a nonlinear system with feedback and the resulting system could potentially become unstable. The authors propose a method that guarantees the stability of feedback systems with fuzzy controllers. Instead of using a fuzzy expert system as a simple static nonlinear mapping device, the new approach arrives at a fuzzy controller with memory. It is shown that the new feedback architecture will remain stable regardless of the fuzzy controller mapping used. This method can also be used to design stand-alone feedback fuzzy systems or recurrent fuzzy systems that are guaranteed to be stable. The application of this approach to the design of fuzzy controllers is illustrated