Robust bounded control for nonlinear uncertain systems with inequality constraints

Abstract

A novel bounded control for nonlinear uncertain systems with inequality constraints is considered. First, a state transformation is applied to satisfy the inequality constraints of the controlled outputs. Therefore, the controlled outputs are within the desired bounds. Next, a diffeomorphism is introduced for the control inputs. Based on that, the control inputs are transformed to be bounded functions. The maximum and minimum of the control inputs can be artificially set by choosing a proper bounding function. This control scheme is able to guarantee uniform boundedness and uniform ultimate boundedness. The simulation shows that the control cost of the novel bounded control and the error of the controlled system are smaller than LQR control, regardless of the uncertainty.