In this note we consider the problem of robust stabilization of the class of uncertain discretetime systems with constant and bounded delay in the state. Such a stabilization is proposed considering performance issues such as H∞-guaranteed cost and the regional pole location of the closed loop system. We revisit this problem with an approach based on LyapunovKrasovskii function, avoiding the classical one which is directly based on the system augmentation. For this proposal, we found an auxiliary system with multiple delays in the state such that if it is Schur-stable then the original state delayed system has a specified regional pole location. All system matrices are supposed to belong to a polytopic set with known vertices. Some numerical examples are given to illustrate the proposal.
I. IntroductionThe characterization of the performance of a system is a quite important issue in both theoretical and practical aspects of control systems. Two quite useful kinds of performance characterization are i) the so called Dstability [1] analysis where a sub-set of the complex plane is certified as containing all poles of the system, and ii) the H ∞ guaranteed cost between an exogenous input and the controlled output. Perhaps the main advantage of the characterization via D-stability analysis remains on the connections of this approach with the classical control theory [2], which provides the user with some useful engineering insights. In the second case, the H ∞ guaranteed cost has been successfully used in a wide range of applications and theoretical developments, as can be easily verified in the literature of control systems. The conjoint use of these two performance characterization approaches may be of interest to improve, for example, the transient performance and also to assure a minimal level of rejection of exogenous signals in controller design cases [3], [4].