Robust adaptive control of uncertain discrete-time state-delay systems

This paper focuses on the controller resilience and performance deterioration issues due to inaccuracies in controller implementation. It addresses the problem of resilient adaptive control problem for a class of discrete-time state-delay systems and normbounded uncertainties against controller gain variations. Adaptive control schemes are constructed for the case of known gain perturbation bounds and then extended to accommodate unknown norm-bounded perturbations. Necessary and sufficient conditions for delay-independent asymptotic stability are established. An expanded state-space system called the 'Compact Form' is established to derive delay-dependent criteria for stability and adaptive stabilization schemes. All the developed results are conveniently expressed in linear matrix inequalities format. A detailed simulation result is presented to demonstrate the developed theory. (c) 2007 Elsevier Ltd. All rights reserved.