Prescribed Performance Control for a Nonlinear System With Actuator Saturation via Anti-Windup Design

In this paper, within the prescribed performance control framework, we revisit the output tracking problem of a nonlinear system with input saturation, user-specified performance and external disturbances. To handle the intrinsic conflict between actuator saturation and performance requirements, we introduce a novel auxiliary system, which is driven by an artificial saturation nonlinearity, to generate modification signals for relaxing the prescribed performance functions. To further alleviate the adverse effects caused by actuator saturation, we incorporate a new performance-based anti-windup compensator into the control framework. In particular, the auxiliary system is designed to adjust the external performance requirements, and the anti-windup compensator is used for improving the internal saturation handling capability. Moreover, we employ a predetermined weighting coefficient to balance between the auxiliary system and the anti-windup compensator for better control performance. To deal with external disturbances, we construct a series of disturbance observers. With the help of dynamic surface control strategies, we develop a state-feedback control law. Theoretical analysis establishes the boundedness of all signals. Finally, an academic example and a tunnel diode circuit system are provided to demonstrate the effectiveness of our control strategy.