Fuzzy direct adaptive control of linearizable systems

In this paper, a fuzzy direct adaptive control scheme is proposed for the nonlinear systems which are input-output linearizable. This class of nonlinear system is represented by a continuous-time fuzzy dynamic model. Based on this fuzzy dynamic model, the continuous-time adaptive control design of the nonlinear system can be transformed into a series of linear adaptive control design. The main idea of this fuzzy adaptive controller is that the parameters of each fuzzy controller are directly tuned to make the output of the system to track the reference trajectory. An on-line update law for the fuzzy controller parameters has been developed based on the tracking error. The computer simulation and real-time application in flow rate process control demonstrate the validity and improved performance of the proposed method over the traditional Model Reference Adaptive Control (MRAC) scheme.