Discrete Kharitonov's theorem and robust control

Starting from the discrete analogue of weak Kharitonov's theorem for monic polynomials, the authors obtain a sufficient stability condition in terms of a polytope by the use of a Schur invariant transformation on the polynomials coefficient space. This approach enables one also to construct a stable n-dimensional simplex with all vertices on the stability boundary. A straightforward robust controller design procedure is proposed for uncertain interval plants and is illustrated with an example.