Robust Controller Design for a Class of Nonlinear Systems Subject to Actuator Saturation

The problem of output regulation for a class of nonlinear systems is investigated in this paper. Practical aspects of a real practical system like existence of time-varying external disturbances, parametric uncertainties and actuator saturation constraint are considered in the process of controller design. This goal is achieved using the Composite Nonlinear Feedback Control method (CNF) along with the Integral Sliding Mode (ISM) controller. In this paper, this idea is applied for a class of nonlinear systems for the first time. Since, the proposed controller may be saturated; exact mathematical analyses are done to approve its performance in the face of actuator saturation constraint and uncertain terms in the model of system. In this regard, a theorem is given and proved based on Lyapunov approach. It guarantees the robust output regulation even if the actuator saturation takes place. In order to show the applicability and effective performance of the proposed controller, it is applied to a fighter aircraft.