ROBUST STABILITY OF MULTIVARIABLE INTERVAL CONTROL-SYSTEMS

In this paper, we will give necessary and sufficient conditions for th e Hurwitz stability of MIMO interval systems. As a consequence of this result, we will give a precise bound on the H-infinity norm of unstru ctured perturbations that can be tolerated by MIMO interval systems co nnected in feedback with these perturbations. We will also consider th e robust version of the Popov problem that considers interval MIMO sys tems subject to nonlinear time invariant sector bounded perturbations and, in turn, obtain a robust stability condition of the Popov problem with mixed perturbations.