Robust Controller Design Based on Sliding Mode Observer in The Presence of Uncertainties and Actuator Saturation

This paper studies the design of a robust output feedback controller subject to actuator saturation. For this purpose, a robust high-gain sliding mode observer is used to estimate the state variables. Moreover, the combination of Composite Nonlinear Feedback (CNF) and Integral Sliding Mode (ISM) controllers are used for robust output tracking. This controller consists of two parts, the CNF part which is taken into account to modify the transient responses and the ISM part which is implemented to reject the disturbances. The two important issues in this paper are: considering the actuator saturation and designing the robust observer-based control law. Moreover, a theorem is given and proved that guarantees even if the actuator saturation takes place, the closed-loop system is stable and the output asymptotically tracks the step reference input. Finally, in order to show the performance of the proposed controller, it is applied to the yaw control of a helicopter and the simulation results verify the theoretical results.