Secure state estimation for cyber-physical systems under sparse data injection attacks: a switched counteraction approach

Cyber-Physical Systems (CPSs), with the intrinsical vulnerability of the cyber layer, are always suffering from malicious data injection (DI) attacks. In this paper, switched counteraction principle based defense strategies are designed for secure state estimation (SSE) of CPSs under sparse DI attacks. Firstly, the physical layer is modelled by a hybrid mechanism, based on which malicious injections are excluded by implementing adaptively switched counteraction searching. Sufficient conditions are established to ensure the feasibility of SSE design. Next, by set cover approach, a defence strategy is presented to further relax the computation burden caused by combinational brute force search. Two numerical examples are given to illustrate the effectiveness and potential of the proposed design methods.