Research On Security Control Of Cyber Physical System Under Hybrid Cyber Attacks

The rapid development and application of Cyber Physical System(CPS)has promoted the development process of informatization,digitization and intelligence in various fields of human production and life.Due to the openness and vulnerability of wireless communication,information perception and data interaction between CPS levels are vulnerable to malicious cyber attacks such as Denial of Service(DoS)attack,False Data Injection(FDI)attack and Replay attack.In order to maximize attack damage and avoid attack detection,attackers usually adopt hybrid cyber attacks mode composed of multiple single attack modes.Compared with a single cyber attack mode,hybrid cyber attacks are diversified in the form of attack,in which attack behavior is highly coupled in time and space scale.This thesis investigates the security control of CPS under hybrid cyber attacks.The main contents are as follows:(1)The predictive compensation control problem based on output feedback is studied for CPS under hybrid cyber attacks consisting of DoS attack and replay attack.Considering the mode characteristics and energy limitation of hybrid cyber attacks,the switching model with nested subsystem structure of CPS is established.By using Lyapunov stability theory and linear matrix inequality(LMI)technique,sufficient conditions of exponential stability are given,and the output-feedback based predictive compensation control strategy is proposed for the stabilization control of CPS.Finally,simulation example is provided to verify the correctness and effectiveness of the proposed method.(2)The dynamic output feedback control strategy with switching subsystem is investigated for CPS with hybrid cyber attacks consisting of DoS attack and FDI attack.Considering mode characteristics of hybrid cyber attacks,the switching model of CPS with subsystem structure is established and the quantitative relationship between hybrid cyber attacks probability and system switching mode is given by using average dwell time method.Sufficient conditions for exponential stability of CPS are derived by utilizing Lyapunov stability theory and linear matrix inequality(LMI)technique,and the dynamic output feedback controller is proposed to stabilize CPS.Finally,the effectiveness of the proposed method is verified by the simulation example.(3)The sliding mode security control strategy with adaptive event triggering communication mechanism is investigated for CPS under hybrid cyber attacks consists of DoS attack and FDI attack.In order to reduce the burden of communication and improve the system performance,an adaptive event triggering mechanism with adjustable trigger threshold is designed.Considering the mode characteristics of different cyber attacks and limited attack energy,a sliding mode function containing attack probability is designed to deal with attack modes composed of different types of attacks.By using Lyapunov stability theory and linear matrix inequality technique,sufficient conditions are derived for the mean-square stability of CPS and the reachability of sliding mode surface,and the sliding mode security control strategy is proposed to realize the stabilization control of CPS.Finally,a simulation example is given to verify the effectiveness of the proposed control strategy.The existing research work and contributions are systematically summarized,and the future research focus is prospected.