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 Omega of output function is given. As long as output function belongs to any closed sector included in Omega, it is shown that the equilibrium point of the closed-loop system can be guaranteed globally uniformly asymptotically stable by an output feedback controller.