Constrained control for linear time-varying systems in the presence of disturbances

The aim of this paper is twofold. In the first part, we revisit the robust invariance for ellipsoidal sets with respect to discrete-time linear time-varying and uncertain systems with bounded additive disturbances. In this context we provide an extension of the invariance condition of the previously published results in the literature. In the second part a novel robust interpolation based control method involving several local unconstrained robust optimal controls is proposed. Among them, one controller plays the role of a performance candidate, while the remaining controllers are used in the interpolation scheme for enlarging the domain of attraction. By using an appropriate objective function, recursive feasibility and a robustly asymptotically stable closed loop behavior are guaranteed.