Type-۳ Fuzzy System for Dynamic System Control

Many dynamic processes are characterized by parametric or structural uncertainties due to internal and externaldisturbances. Existing deterministic models could not handle the uncertainties inherent in these processes. A valuablealternative to control these processes is the use of a type-۳ fuzzy system. Since type-۳ fuzzy systems use threedimensionalmembership functions, they have more capacity to model uncertainties. This paper introduces the designof a type-۳ fuzzy logic system (FLS) for the control of dynamic plants. Utilizing type-۳ fuzzy logic, the architectureof the type-۳ fuzzy control system (T۳FCS) is proposed. The knowledge base of the controller is constructed and itsdesign stages are presented. The inference mechanism of type-۳ FLS is developed using α slices and interval type-۳membership functions. The proposed type-۳ FLS is utilized for controlling nonlinear dynamic plants. The modelingof the proposed T۳FCS is performed and transient response characteristic is derived using different stepwise excitationsignals. A comparison of the designed system with the type-۱ FLS-based system is provided. The obtained simulationresult demonstrates the efficiency of using the proposed type-۳ FLS in the control of dynamic systems characterized byuncertainties.

Keywords:

Fuzzy controller , Type-۳ membership function , type-۳ fuzzy logic , control system