Scaling Factor Adaptation of Fuzzy Controllers

In this paper, the designed schemes for two fuzzy controllers, Mamdani fuzzy controller and Takagi-Sugeno fuzzy controller, through the scaling factor adaptation are proposed. The proposed adaptation laws for the output scaling factor, which respectively result from the direct adaptive approach, are used to appropriately determine the control signal of the fuzzy controllers. The great advantage of the proposed method is that the parameters of fuzzy controllers, including its rules, membership functions, do not need to be changed under control, specially only one adapted parameter is used. Usually, it is not easy to characterize the linguistic control rules and its membership function distribution without expert’s knowledge in those situations when the input variables of fuzzy controller are large. In this study, we first organize the Mamdani fuzzy controller and the Takagi-Sugeno fuzzy controller without any specific experience information about the controlled system. Two adaptation laws are then respectively used to adapt the controller’s output scaling factors such that the resulted control input leading to a good system performance can be achieved. Finally, we apply the proposed fuzzy controllers to controlling a nonlinear system to verify its effectiveness.