Secure estimation and attack detection in cyber-physical systems with switching attack

Cyber attacks on cyber-physical systems bring new challenges to existing methods of fault detection and fault tolerant estimation. In this paper, an approach is proposed for the secure state estimation in cyber-physical systems with switching attacks. The attack signal causes a switch in the system behaviour. We consider only two system modes, nominal mode and attacked mode. As the switching sequence is unknown, information coming from IT cybersecurity layer is used to guide the switching signal of the observer mode. The residual signal provided by the switched observer also influences the switching signal of the observer. The stability of the resulting estimation error dynamics is proven. An example is given to illustrate the advantage of the proposed approach over two other switching observer schemes.