Research On Control Methods For Nonlinear Systems With Unknown Output Functions

This paper considers the design and analysis of stabilizing controller for nonlinear systems with uncertain output function. The main contributions include:Chapter 1 solves the problem of output feedback stabilization for nonlinear systems with unknown output function and control coefficients. Since output function is Lipschitz continuous but not necessary derivable, the maximal sector region of output function is given. As long as output function belongs to the sector, an output feedback controller can be designed to render the closed-loop system globally asymptotically stable. The effectiveness of controller is demonstrated by two examples.Chapter 2 considers semi-global output feedback control for more general nonlinear systems with unknown time-delay and output function. By introducing a new observer and using the backstepping design method and the Razumikhin stability theorem, an output feedback controller is constructed to achieve semi-global stability.Chapter 3 gives summary and outlook of the thesis.