Research On Security Control Strategy Of Cyber-physical System Under Denial-of-service Attacks

Cyber-Physical System(CPS)is formed by the deep integration and interaction of com-puting,communication and control technology,which realizes the mapping interaction and collaborative optimization of key elements(such as people,environment,etc.)in physical entity space and information virtual space.CPS can not only efficiently meet the requirements of operation response,but also achieve the purpose of dynamic optimization and fast iteration within the system.Different from the traditional point-to-point control mode,each component relies on sharing,open and heterogeneous communication network to achieve close association and high degree of networking,so it is applied in many fields.However,due to the vulnerability of CPS's high integration,it is vulnerable to cyber attacks.In recent years,security incidents related to CPS have emerged one after another,which has severely affected the social stability and economic development of various countries.Due to the characteristics of easy implementation,high attack frequency and large damage range,denial-of-service(DoS)attack has become the focus of network security research.DoS attacks prevent measurement or control signal updates by occupying network communication resources,leading to system performance degradation or even instability.Therefore,this article conducts the security control of packet loss and delay caused by DoS attack in CPS based on the optimization of communication transmission strategy from the perspective of control theory.The main work contents are as follows:(1)Aiming at the security problem of CPS under energy-constrained DoS attacks,an output feedback predictive control method based on packet loss compensation is proposed.Firstly,it is reasonable to assume that the maximum number of packet losses caused by continuous DoS attacks is bounded,and establish a nested switching closed-loop system under different DoS attack modes.Secondly,the sufficient conditions of exponential stability are derived using the Lyapunov function under any switching rule,and the exponential decay rate is obtained.Then,the predictive control sequence is solved using linear matrix inequalities(LMIs).Finally,an inverted pendulum example simulation is used to verify the effectiveness of the designed control strategy in ensuring the safety performance of CPS.Compared with the existing research results,the proposed static output feedback predictive control(SOFPC)strategy only uses the last successfully received measurement output to compensate for the packet loss caused by the DoS attack,which greatly reduces the dependence on state data.(2)On the basis of predictive control theory,event-triggered mechanism is introduced.That is,to address the problem of limited communication resources in CPS,a predictive control strategy based on the idea of event-triggered is adopted to compensate for the uncertain data packet loss caused by DoS attack.At first,considering the limited energy of attacker,the DoS attack is established as a switching system model with an event-triggered communication mechanism.The Lyapunov stability theory and switching system analysis method are used to obtain system safety conditions.Then,Lyapunov stability theory and switching system analysis method are used to obtain the stability criterion;At the same time,the security control sequence is designed by the data information successfully triggered on the sensor side under the DoS attack.At last,a simulation example illustrates the reliability and effectiveness of the event-triggered predictive control(ETPC)strategy in ensuring system security control and saving communication resources under DoS attacks.(3)Considering the dynamic event-triggered mechanism,the security control method of like switching event-triggered with DoS attack and free DoS attack interval division is studied.Based on the fact that DoS attack has active period and dormant period,the behavior duration is equivalent to the maximum allowable transmission interval under different triggering conditions,that is,the optimal communication transmission strategy is designed with or without DoS attack.The stability and H_?performance of time-delay systems are derived by using Lyapunov-Krasovskii functional.In additon,the design criteria of safety controller are also given.The proposed like switching event-triggered control(LSETC)strategy describes the characteristics of DoS attack duration in bounded time domain,and realizes the collaborative optimization design of communication strategy and security control strategy in uncertain network environment.