OBSERVER DESIGN IN RECEDING-HORIZON PREDICTIVE CONTROL

This paper considers the robust implementation of a class of predictiv e control methods represented by GPC. Such controllers are in two-degr ees-of-freedom form where there are dynamics in both the forward and t he feedback paths. The 'tuning knobs' of predictive controllers determ ine the characteristic polynomial P-c, and for a given P-c the observe r or prefiltering polynomial T in the feedback path determines the rob ustness of the closed loop. Previous intuitive guidelines on the selec tion of T are shown to be limited in their effectiveness. For an open- loop stable plant, a simple criterion is provided which allows the fee dback dynamics to be specified so as to enhance robustness. The T poly nomial is then chosen to satisfy this criterion. In addition, robust d esign through T is related to an H-infinity-optimal control scheme usi ng the so-called Q-parametrization. Despite its simplicity, the new pr oposed approach to the design of T is seen to result in robustness com parable with that obtained from the H-infinity method.