Observer-Based Control of Uncertain Systems with Nonlinear Uncertainties

Global asymptotic stabilization of nominally linear uncertain systems is considered where uncertain elements in the plant are modelled as cone bounded nonlinearities. At first, a linear time-invariant state feedback law ensuring global aymptotic closed-loop stability is obtained. The algorithm which calculates such a feedback law is simple and straightforward. It does not involve repeated solutions of a parameter dependent algebraic Riccati or any such nonlinear equations. Any state feedback law thus developed can then be implemented via an observer specially designed to preserve the global asymptotic stability of the closed-loop system.