In this paper, a design scheme for the fuzzy controller through width adaptation of the universe of discourse is presented. The proposed adaptation law, which results from the direct adaptive approach, is used to appropriately determine the width of the output variable, and the result of the membership functions in the THEN part will vary with the width adaptation. The main advantage of the proposed method is that the structure of the fuzzy controller does not need to be changed while using a common design procedure. We know that it is not easy to characterize the linguistic control rules and its membership function distribution without expert knowledge, especially in those cases when the input variables of the fuzzy controller are increased. In this study, we first organize a fuzzy controller without any specific experience of the controlled system. An adaptive law is then used to tune the width of the universe of discourse in the THEN part to appropriately determine each membership function's distribution. Finally, a nonlinear system simulation example is applied to verify the effectiveness of the proposed fuzzy controller.
