Research On Security Control And Filtering Problem Of Networked System Under Multi-Source Cyber Attacks

With the rapid development of information technology and control theory,networked control systems with the advantages of low cost,high reliability,and convenient maintenance have been integrated into all aspects of production and life,and have occupied an important position.However,the introduction of communication networks breaks the original closed nature of control systems.The vulnerability and openness of communication networks have made networked control systems face the threat of malicious cyber attacks.Therefore,how to implement security control of networked control systems under cyber attacks has attracted more and more researchers’attention.Currently,the research on the security control and filtering issues of networked systems under multi-source cyber attacks is still in its initial stage,especially considering how to reasonably allocate network communication resources under multi-source cyber attacks.Improving the control performance of networked systems while ensuring system security control still need to further research.Therefore,this thesis focuses on the issues of security control and filtering algorithm design for networked control systems under multi-source cyber attacks.The main research covers three areas:1)The design of robust H_∞filtering algorithms is investigated for networked control systems with random denial of service attacks and replay attacks.The static quantization mechanism is adopted to alleviate the pressure of bandwidth constraint in communication networks and improve computational accuracy of the system,and two mutually independent Bernoulli variables are introduced to describe the occurrence of denial-of-service attacks and replay attacks.Subsequently,the model of networked control system with multiple constraints such as cyber attacks and external disturbances is established.By using Lyapunov stability theory and stochastic analysis methods,sufficient condition for mean-square exponential stability of the filtering error system is derived,and the robust H_∞filter with static quantization mechanism is designed.Finally,the practicality of proposed filtering algorithm is verified by an uninterruptible power supply system and a cloud-aided quarter-vehicle suspension system.2)The problem of event-triggered H_∞dynamic output feedback control is investigated for networked control systems with random denial of service attacks and replay attacks.In order to reduce the network communication burden,the dynamic event-triggered communication mechanism is utilized to transmit sensor measurement information.Considering the random characteristics of multi-source cyber attacks,the model of networked system is established,which includes mode characteristics of denial-of-service attacks and replay attacks.Then,by using Lyapunov stability theory and linear matrix inequality techniques,sufficient conditions for mean-square stability of the closed-loop system are given,and an H_∞dynamic output feedback control strategy is proposed under the dynamic event-triggered mechanism.Finally,the effectiveness of presented control strategy is verified by numerical example and an autonomous underwater vehicle system.3)The guaranteed cost control problem is investigated for networked control systems with periodic denial of service attacks and false data injection attacks based on dynamic event-triggered mechanism.The packet dropout caused by periodic denial-of-service attacks and the inherent packet dropout in communication networks are modeled as Bernoulli random distribution processes,and the false data injection attack is considered as a special type of external disturbance.In such a framework,the closed-loop networked system model is presented through state-feedback control strategy.Then,by using Lyapunov stability theory and matrix decomposition theory,sufficient conditions for the stability of closed-loop system are derived,and the state feedback control strategy with a given performance level and event-triggered mechanism is designed.Finally,the effectiveness of the designed control scheme is verified by means of an RLC circuit model.Finally,the main research work and contributions of the thesis are summarized,and the future research priorities are prospected.