Semiglobal output feedback control for uncertain nontriangular nonlinear systems with sector-bounded unknown measurement

The problem of semiglobal stabilization for nontriangular nonlinear systems with unknown control coefficients and uncertain output function is investigated in this paper. By virtue of homogeneous domination technique, a novel nonrecursive design approach is presented to construct the semiglobal controller. To that end, a new output-driven reduce-order observer is developed to estimate the unmeasurable states. Moreover, it has been shown that we can determine the maximal sector bound of output function, in which an output feedback controller can be designed to render the closed-loop system semiglobally stable. The effectiveness of controller is demonstrated by a ship simulation.