A dynamic defuzzification method for interval Type-2 Fuzzy Logic Controllers

In Type-2 Fuzzy Logic Systems (T2FLS), the output of a type-2 fuzzy inference engine needs to be type-reduced in order to obtain crisp output in defuzzification process. The type reduced set is an interval type-1 set determined by the left and right end points. In conventional defuzzification method, the defuzzified crisp output is obtained by averaging these left and right end points of the type reduced set. With this defuzzification method, the capability of the T2FLS cannot be utilized effectively. Type-2 Fuzzy Logic Controllers (T2FLCs) is very effective in various control applications. In this study, a new defuzzification method which uses a linear combination of the left and right end points of the type reduced set is proposed for T2FLCs. This linear combination is formed using the current system error and change of error. In this manner, it has been possible to enhance the performance of the T2FLC. To demonstrate the effectiveness of the proposed defuzzification method, various simulations are presented.