Recent advances in event-triggered security control of networked systems: a survey

Security control of networked control systems (NCSs) under vulnerable communication environments has become an important topic both in theory and in practice. Due to malicious attacks, some control issues like event-triggered control are difficult to be addressed since digital signals may be modified by hackers when transmitted through the communication networks. This paper aims to provide a survey of recent advances in event-triggered security control for NCSs under malicious attacks. First, several typical models on cyber-attacks from the communication layer are elaborated. Second, a number of secure control results reported in the literature are reviewed and in-depth analysis is made on several improved event-triggered strategies resilient to cyber-attacks, including the hybrid-triggered strategy, the adaptive event-triggered strategy, the dynamic event-triggered strategy, the memory-based event-triggered strategy, the switching-like event-triggered strategy, and the stochastic event-triggered strategy. Third, under randomly occurring denial-of-service attacks, an application of part event-triggered secure resilient control to power systems with a load frequency control scheme coordinated electric vehicles is analysed. Finally, several challenging issues on event-triggered control based on cyber-attacks are presented to direct the future research in the field.