A predictive reference governor for constrained control systems

A method based on conceptual tools of predictive control is described for solving tracking problems wherein pointwise-in-time input and/or state inequality constraints are present. It consists of adding to a primal compensated system a nonlinear device called reference governor (RG) whose action is based on the current state, set-point, and prescribed constraints. The aim of the RG device is that of modifying, when necessary, the reference in such a way that the constraints are enforced and the primal compensated system maintains its linear behavior. The RG action is computed on-line by solving, at each sampling time, a constrained quadratic programming problem that usually requires low computational times also for systems of relatively high order. The overall system is proved to fulfill the constraints, be asymptotically stable, and exhibit an offset-free tracking behaviour, provided that an admissibility condition on the initial state is satisfied