Observer-Based Event-Triggered Sliding Mode Security Control for Nonlinear Cyber-Physical Systems Under DoS Attacks

In this paper, we investigate the observer-based integral sliding mode security control problem for a class of time-delay nonlinear discrete-time disturbed cyber-physical systems (CPSs) subject to dual-channel aperiodic asynchronous denial-of-service (DoS) attacks. An adaptive event-triggered protocol (AETP) is proposed to save network resources, whose triggering threshold is dynamically adjusted. The DoS attacks are described by the occurrence frequency and the durations, and a corresponding neural network (NN)-based switched observer is employed to estimate the unmeasurable state of the original system. By means of this model, a novel switched system is constructed under the designed equivalent integral sliding mode controller. Sufficient conditions are given to ensure the input-to-state practically stability of the closed-loop system while achieving the desired security level. Furthermore, the explicit expressions for the gain matrices of the controller and the observer are derived with the help of solving linear matrix inequalities. In order to strengthen the robustness and suppress chattering of the system, a robust integral sliding mode control (RISMC) algorithm is developed under the reaching condition. Finally, a water supply distribution system is employed to verify the advantages of the developed control approach.
Note to Practitioners
—With the advancement of long-distance communication technologies, the open network environment poses an increasingly serious security threat to the operation of CPSs. In the context of communication scheduling, cyber attacks will lead to severe data sparsity problems, which inevitably deteriorate system performance. In addition, geographically dispersed CPSs tend to face more complex disturbances and nonlinearities than traditional systems. Therefore, developing resource-aware control algorithms and analysis techniques to comprehensively improve the security and robustness of CPSs are still a challenging problem. This article focuses on the observer-based event-triggered security and robust control of CPSs subject to dual-channel DoS attacks. For the sake of the burden of communication bandwidth, a novel AETP is developed to schedule data exchange so as that save network resources. In view of the threat of aperiodic DoS attacks and external disturbances to CPSs, an observer-based RISMC scheme is proposed. Subsequently, simulation results show that the proposed method can achieve the desired security performance with sufficient robustness.