Functional observers design for two interconnected linear systems via LMI

This paper proposes functional observer for each subsystem of two interconnected system. The new approach that we use to express the observation error permits to use results on large scale delay systems to solve the problem. The proposed observers are free of the interconnection terms and the observation error are unbiased. The observer are designed via some gains which are obtained via LMIs (i.e. via a tractable approach) from the Lyapunov stability results. An algorithm is given for the computation of the observers, then a numerical example shows the effectiveness of the approach that can be extended for the H_infinity filtering of linear and nonlinear large scale systems.