Interval Observer Design for Nonlinear Interconnected Systems via Ellipsoid Approach

In this paper, an interval observer is designed for discrete time-varying nonlinear interconnected systems in which the estimated state set is described by using an ellipsoid. The state estimation accuracy is improved by expressing the higher-order infinitesimal terms of nonlinear Taylor expansion with ellipsoids instead of disregarding them. In order to reduce the communication burden, the weighted try-once-discard (WTOD) protocol is used to schedule the transmission order of the subsystem components. Furthermore, the interval observer gain matrices are calculated by solving linear matrix inequalities. At the end of this paper, a numerical simulation is given to prove the effectiveness of the proposed interval observer.