Design of reference governor for a class of nonlinear systems with input constraints

This paper presents a design method of the reference governor for a class of nonlinear systems with input constraints. When the input has a constraint, the input saturation might happen and thus, the controller cannot work correctly. Furthermore, the output might diverge in the case of an open loop unstable system. To overcome this problem, a novel approach to the design of a reference governor is proposed. A nonlinear system diffeomorphic to a normal form is considered and additionally, a bounded disturbance in the control input is considered. In the proposed method, the behaviors of the states and input are predicted and the reference is modified so that the predicted input never exceeds the saturation limits and the modified one is closest to the given command among the values which are achievable without the input saturation. The convergence of the newly generated reference trajectory is proved and some simulation results are included to verify the performance of the proposed method.