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.