Global stabilization of uncertain nonlinear time-delay systems by output feedback

In this paper, constructive control techniques have been proposed for controlling strict feedback (lower triangular form) nonlinear systems with a time-varying time delay in the state. The uncertain nonlinearities are assumed to be bounded by polynomial functions of the outputs multiplied by unmeasured states or delayed states. Based on the using of a linear dynamic high gain observer in combination with a linear dynamic high gain controller, the delay-independent output feedback controller making the closed-loop system globally asymptotically stable (GAS) is explicitly constructed.