Observer-based anti-windup design of flexible satellite attitude system

The paper addresses the design of anti-windup control for flexible satellite attitude system with actuator saturation. First, a linear observer-based controller is designed to stabilize the satellite attitude system and realizes flexible vibration suppression without considering saturation. According to the difference between the controller output and the saturated actuator output, an anti-windup method which utilizes the dynamics of the observer is proposed for dropping off the saturated effect. It is shown that the resulting closed-loop system of flexible satellite obtained from the controller plus the anti-windup gains can be described as a linear system with the dead-zone nonlinearity. Finally the generalized inequality sector conditions are used to obtain stability conditions based on quadratic Lyapunov function. The simulation results show that the scheme is feasible.