Reliable Control Policy of Cyber-Physical Systems Against a Class of Frequency-Constrained Sensor and Actuator Attacks

This paper is concerned with reliable control problems of cyber-physical systems against a class of frequency-constrained sensor and actuator attacks. We consider a continuous-time linear physical system equipped with an observer-based abnormal detector, and it is assumed that control signals and partial sensor outputs transmitted via network layers are vulnerable to cyber attacks. With the use of detection mechanisms of the abnormal monitor, an upper bound of the worst stealthy attacks is obtained, which is composed of the information of the detector's threshold, the attack's structure, and frequency characteristic. By exploiting the bound information, a novel attack compensator, which can stabilize the system with a nearly desired system performance, is proposed for a situation where an attack may occur without triggering an alarm. Finally, the effectiveness of the proposed control policy is verified by a numerical example.