Event-triggered UIO-based security control for discrete-time systems under deception attacks

Abstract

Deception attacks are regarded as the most typical cyber attacks, which may damage system performance or even cause system paralysis. Deception signals are well-designed by the attackers and may occur on any communication channel, which makes deception attacks relatively stealthy and difficult to detect. In this paper, for linear discrete-time systems that are vulnerable to deception attacks randomly occurring on the controller-to-actuator channel, a novel event-triggered unknown input observer (EUIO) is developed to suppress the impact of deception attacks and unknown inputs on the system and save communication resources. Firstly, different from existing results, the deception signal together with the system unknown input (UI) is modeled as a new multiple UI (MUI). Then, an algebraic expression of the MUI and the system state is established by designing an event-triggered interval observer (EIO). Subsequently, using the algebraic relationship, an EUIO is designed to asymptotically estimate the system state and the MUI simultaneously. Furthermore, an EUIO-based compensation controller is designed by incorporating both state estimation and MUI reconstruction (MUIR) to eliminate the influence of MUI on the system. Under the asymptotic convergence property of the estimations of the EUIO and the significant result of MUIR decoupling the control input, the stability of the closed-loop system can be ensured even if the system suffers from deception attacks, external disturbances, actuator faults, etc. Finally, the feasibility, effectiveness, and advantages of both the EUIO and EUIO-based controller are verified by two examples and comparisons.