Global stabilization by output feedback for a class of nonlinear systems with uncertain control coefficients and unmeasured states dependent growth

This paper considers the problem of global stabilization by output feedback for a class of nonlinear systems with uncertain control coefficients and with unmeasured states dependent growth. Mainly due to the uncertain control coefficients,the prob-lem has remained unsolved and its major difficulty stems from the inapplicability of the commonly used high-gain like observer. By introducing an appropriate state transformation and a thoroughly novel observer based on high-gain K-filters,the backstepping design approach is successfully proposed to the output-feedback con-troller for this class of systems. It is shown that the global asymptotic stability of the closed-loop system can be guaranteed by the appropriate choice of the control pa-rameters.