Nonlinear control system design for unstable plants with input saturation using robust right coprime factorization

Operator-based robust right coprime factorization approach is an interesting approach. It provides an effective framework for nonlinear unstable system. In practice, the input constraint always exists, which induces that the real control input is different from the controller output, thus the input constraint may destabilize the system. As for linear system with input saturation, such as with anti-windup, some methods have been proposed. However, control system design for nonlinear plants with input saturation has seldom been studied due to the difficulties in dealing with nonlinearity. In this paper, a new control system design for nonlinear unstable plants with input saturation is proposed. Based on the robust right coprime factorization, an operator based switch controller is designed, which avoids the unstable region. Moreover, based on the proposed design scheme, the output tracking performance is also realized, and the effectiveness of the proposed method is verified by simulation.