High gain observer based higher order sliding mode control: Application to an induction motor

In this paper, a novel Higher Order Sliding Mode Control (HOSMC) for uncertain nonlinear systems is presented. The proposed controller allows obtaining an exponential stability as well a finite time convergence to the sliding surface and guarantees robustness against uncertainties and external matched disturbances. Furthermore, the synthesis of the control law depends explicitly on the states of the system. But, in practice, most of systems admit one or more unknown states. Such problem represents a serious drawback when implementing the controller in real time. To solve this problem we incorporate a High Gain Observer (HGO) into the controller to estimate the missing states. These techniques of control and observation are applied to an induction motor system. Numerical simulations are developed to show the effectiveness of the resulting controller.