Observer-Based Fault-Tolerant and Resilient Control Under Physical Faults and Integrity Cyberattacks

In this article, we investigate fault-tolerant and resilient control approaches for cyber-physical systems within a unified control and detection framework. Particularly, a novel strategy is presented to simultaneously detect and accommodate anomalies in cyber-physical systems subject to multiplicative physical faults and additive integrity cyberattacks. An observer-based cyber-secure system configuration is first analyzed by means of the coprime factorization technique, wherein multiplicative faults are characterized by coprime factor uncertainties. It is revealed that fault- and cyberattack-induced variations possess distinct attributes with respect to the closed-loop dynamics. This observation motivates a collaborative detection scheme to distinguish both types of anomalies. Specifically, a performance-based fault detector is implemented on the plant side, delivering fault detection results to the monitoring and control (MC) side, where an observer-based attack detector operates collaboratively. Subsequently, the local and remote controllers are reconfigured to enhance the fault tolerance and attack resilience against faults and cyberattacks. To provide more independent design freedoms, the residual signal derived from the controller dynamics is incorporated into the Youla parameterization-based stabilizing controller. Finally, the proposed scheme is verified on a leader-follower robot system.