Global Output Feedback Stabilization of Nonlinear Systems with a Time-Varying Power and Unknown Output Function

This paper studies the problem of global output feedback stabilization for a class of nonlinear systems with a time-varying power and unknown output function. For nonlinear systems with a time-varying power and unknown continuous output function, by constructing a new nonlinear reduced-order observer together with adding a power integrator method, a new function to determine the maximal open sector Ω of output function is given. As long as output function belongs to any closed sector included in Ω, it is shown that the equilibrium point of the closed-loop system can be guaranteed globally uniformly asymptotically stable by an output feedback controller.