Robust reliable control for a class of uncertain nonlinear state-delayed systems

This paper deals with the problem of robust reliable control design for a class of nonlinear uncertain state-delayed systems. The system under consideration involves state time delay, parameter uncertainties and unknown nonlinear disturbances. The nonlinearities are assumed to satisfy the boundedness condition, and the parameter uncertainties are allowed to be time-varying unstructured. The purpose of this problem is to design the state feedback controller such that, for all admissible uncertainties as well as actuator failures occuring among a prespecified subset of actuators, the plant remains globally exponentially stable, independently of the time delay. An effective, modified algebraic Riccati equation approach is developed to solve the problem addressed. It is shown that designed nonlinear time-delay control systems provide guaranteed robust reliable stability despite possible actuator failures. We present an illustrative example to demonstrate the applicability of the proposed design approach. (C) 1999 Elsevier Science Ltd. All rights reserved.