Abstract

Cyber-physical systems (CPS) are the backbone of critical infrastructures such as power grids, transportation networks, and water treatment facilities. While CPS offer numerous benefits, they face significant cyber-security challenges due to their large cyber surface, which allows adversaries to launch cyber-attacks. These attacks can be stealthy, making systems unstable while remaining undetected. Key challenges in CPS security include cyber-attack detection and isolation, resilient control design against adversaries, and privacy preservation. Due to bandwidth limitation
challenges, designing CPS with event-triggered communication—where components transmit information only when necessary—can reduce network congestion and optimize communication bandwidth. This thesis addresses several cyber-security challenges in CPS with event-triggered communication. The first part focuses on cyber-attack detection and isolation. Detection mechanisms are developed to identify attacks such as covert attacks and zero dynamics attacks. By leveraging event-triggered communication, we propose mechanisms capable of detecting highly resourced attacks even when adversaries have full knowledge of the detection system. The methodology also includes isolation mechanisms to isolate under-attacked communication channels.
The second part studies resilient control design in event-triggered CPS. A resilient control protocol is developed against covert attacks using auxiliary systems and observers, ensuring the system state remains Uniformly Ultimately Bounded (UUB). For zero dynamics attacks, a bank of auxiliary systems estimates the attack signal, which is then incorporated into a resilient control protocol, ensuring UUB under this stealthy cyber-attack
as well.
The third part investigates a Multi-Agent System (MAS) framework, where we address event-triggered resilient consensus control under False Data Injection (FDI) attacks among heterogeneous agents. By using a node decomposition methodology, the proposed control protocol ensures both resilience to cyber-attacks and preservation of agents’ privacy.
Overall, this thesis considers both Cybersecurity challenges and bandwidth imitations by designing robust detection, isolation, and resilient control protocols against various cyber-attacks while maintaining efficient network operation through considering event-triggered communication.