Exponential function based decoupled fuzzy sliding mode control of nonlinear systems

In this paper, exponential function based decoupled fuzzy sliding-mode control for highly nonlinear systems is proposed. The decoupled control method provides a simple way to achieve asymptotic stability for a class of fourth-order nonlinear system into two second-order subsystems by a separate control objective expressed in terms of a sliding surface for each subsystems. Using the proposed method the second subsystem is successfully incorporated into the first one via a two-level decoupling strategy. In controller design method, the two terms of sliding mode control the reaching mode and sliding mode are designed by fuzzy logic control and equivalent control method respectively. In the proposed controller design approach, the output membership functions of the fuzzy sliding mode control are defined on the universe of an exponential function gain. The exponential function reduces the reaching time to the switching surface by dynamically adapting the variation of the controlled system, which allows reduction in system susceptible to parameter perturbation and external disturbances during reaching phase. Two simulation results of a cart-pole and ball-beam systems are shown to demonstrate the effectiveness of the proposed method.