Sliding-mode observer for uncertain systems. I Linear systems case

A sliding mode observer for linear uncertain systems is proposed. The advantage of the proposed observer is that it works under much less conservative conditions than Wallcot et al.'s observer (1987). In addition, we address the issue of estimating a function of the state as well as unknown inputs or structural uncertainties. Further, the idea is extended to a general class of nonlinear uncertain systems. Numerical examples are used to illustrate the validity of the proposed observer design strategy.