Global output feedback practical tracking for time-delay systems with uncertain polynomial growth rate

摘要

In this paper, the problem of global practical output tracking is investigated by output feedback for a class of uncertain nonlinear time-delay systems. Compared with the existing results, we allow the nonlinearities to nonlinearly grow in unmeasured free-delay and time-delay states with the uncertain time-delay output polynomial growth rate. Based on the ideas of universal adaptive control and dead zone, we develop an adaptive high-gain observer with a novel monotone non-decreasing dynamic law. By the Lyapunov-Krasovskii theorem, a memoryless controller is constructed to achieve global practical output tracking for uncertain nonlinear systems with multiple time delays. Finally, two examples are given to illustrate the usefulness of our results. (C) 2015 Published by Elsevier Ltd. on behalf of The Franklin Institute