Functional interval observer for discrete-time switched system under stealthy attacks

This paper deals with functional interval observer design for discrete-time switched systems under stealthy deception attacks. First, the boundaries of the attack are obtained by designing interval observers. Then a two-step method to design the functional observers by zonotope is presented. For the first step, an $H$∞ functional observer is presented and as the second step, the zonotope method is applied to obtain the boundaries of states. An illustrative example provided in the last section demonstrates the effectiveness of the proposed method.