Output feedback stabilization for high-order uncertain feedforward time-delay nonlinear systems

This paper addresses the output feedback stabilization problem for a class of high-order uncertain feedforward time-delay nonlinear systems. Under a weaken assumption that the powers of nonlinear functions are relaxed to an interval, the new control strategy implanting sign functions into homogeneous domination idea and observer construction allows time-varying delays to coexist in system state and control input. With the aid of delicate selections of design parameters, observer gains and Lyapunov-Krasovskii functionals, it is shown that the closed-loop system is globally asymptotically stable.