Control of constrained nonlinear systems via reference management

For a broad class of nonlinear continuous-time systems this paper addresses the problem of satisfying input and/or state hard constraints. The approach consists of adding a reference governor to a primal compensated nonlinear system. This is a predictive discrete-time device which, taking into account the current value of the state, filters the desired reference trajectory in such a way that a nonlinear primal compensated control system can operate in a stable way with satisfactory tracking performance and no constraint violation. The resulting hybrid system is proved to fulfil the constraints, as well as stability and tracking requirements, and the related computational burden turns out to be moderate and executable with current computing hardware.