New H∞ control approaches for interval time-delay systems with disturbances and their applications

In this paper, the H-infinity performance and control problems for linear systems with interval state or input delays and disturbances are investigated. In order to exploit more information on the delay range, the quadruple -integral terms and quadratic forms of triple integrals are introduced into the Lyapunov-Krasovskii functional (LKF). Particularly, an improved integral inequality is developed for estimation of the cross terms in triple -integral type, which displays significant improvement over the Wirtinger inequality. As a result, a less conservative H-infinity performance criterion is derived without requiring many slack variables. Based on the criterion, the H-infinity controller design approaches are obtained. Besides the numerical examples, the applications to the practical systems are also provided to illustrate the effectiveness of the proposed approaches. (C) 2016 ISA. Published by Elsevier Ltd. All rights reserved.