Resilient Control for Cyber-Physical Systems Against Denial-of-Service Cyber Attacks Using Kharitonov's Theorem

Cyber-physical systems (CPS) and networked control systems (NCS) integrate control systems with modern information technologies. Alongside the benefits of these control systems, there has been a growing concern regarding the security of critical infrastructures that use these technologies. Communication channels in a CPS are susceptible to various cyber-attacks, such as Denial-of-Service (DoS) attacks, which lead to severe time delays, missed data, control performance degradation, and instability. In this article, a conservative model has been considered for the system when a DoS attack occurs, which makes it possible to design a robust PI controller based on Kharitonov's theorem for mitigating the effects of DoS attacks. Then, to illustrate the effectiveness of the proposed robust PI controller for reducing DoS attack effects, another PI controller tuned by the Ziegler-Nichols method has been designed, and the performance of these two PI controllers compared by practical implementation on a CPS (liquid-level networked control system). The results show that the robust PI controller based on Kharitonov's theorem performs better than the PI controller tuned by the Ziegler-Nichols method to mitigate the influences of DoS attacks on the behavior of the CPS.