Attack isolation and location for a complex network cyber-physical system via zonotope theory

Abstract

This paper investigates the attack isolation (AI) and attack location (AL) problems for a cyber-physical system (CPS) based on the combination of the H-infinity observer and the zonotope theory, where the real control plant in the physical layer is a nonlinear complex network system. Firstly, for actuator AI and AL purposes, two robust H-infinity observers are designed and the stabilities of them are analyzed based on linear matrix inequalities (LMIs). Secondly, the zonotope theory is used to the error dynamic system of the H-infinite observer such that it can calculate iteratively the interval state estimation if the CPS has no attacks. Third, two residuals are constructed and their interval estimates are also given, and furthermore, based on the residual interval estimates, both actuator AI and AL schemes are developed. Besides, sensor AI and AL issues are discussed by modifying the actuator AI and AL schemes. Finally, the effectiveness of the proposed methods is illustrated through a simulation example.