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 s tate inequality constraints are present. It consists of adding to a pr imal compensated system a nonlinear device called reference governor ( RG) whose action is based on the current state, set-point, and prescri bed constraints. The aim of the RG device is that of modifying, when n ecessary, the reference in such a way that the constraints are enforce d and the primal compensated system maintains its linear behavior. The RG action is computed on-line by solving, at each sampling time, a co nstrained quadratic programming problem that usually requires low comp utational 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 admi ssibility condition on the initial state is satisfied. (C) 1998 Elsevi er Science B.V. All rights reserved.