An Output Feedback Variable Structure Control Based on The LTR Observer

Most previous studies on variable structure control of uncertain systems relied on state feedback. This paper considers an output feedback variable structure control for
MIMO systems subject to large matched uncertainties. The proposed control utilizes an LTR observer for state estimation in the face of large matched uncertainties. The
LTR observer is shown to reject almost completely the uncertainty’s adversary effect by achieving an arbitrarily small gain from the uncertainty to the state estimation error.One then utilizes the LTR observer to synthesize an observer-based state feedback variable structure control, achieving practical stability in the sense that the system state is asymptotically driven into a residual set containing the origin, with the size of the residual set approaching zero as a design parameter in the observer Riccati equation approaches infinity.