Design Of Sliding Mode Control For Cyber-Physical Systems Under Network Environments

In recent years,due to the technological progress of computer and communication equipment in power consumption,mobility and efficiency,the cyber-physical systems arise at the historic moment and rapid development.Meanwhile,the strong coupling between the information network and the physical world also brings new challenges to the industry,among which the most prominent problem is the cyber security and limited channel bandwidth.As a result of the open communication platform,cyber-attacks frequently invade the cyber-physical systems,such that systems cannot run normally.Besides,in cyber-physical systems,message data and control signals are transmitted over the network to the remote end,which may lead to channel congestion and cannot be satisfied with the real-time demands of the system.For the sake of solving these problems,this thesis combines sliding mode control and event-triggered control methods to design the security control strategy of cyber-physical systems under network environments.The main work is as follows:(1)Two kinds of sliding mode control design methods are proposed to solve the security control problem of cyber-physical systems under the false data injection attacks.Firstly,the threshold information of anomaly detection mechanism is used to obtain the upper bound information of attacks,and a robust sliding mode control method is constructed by using the obtained upper bound information of the attacks.Secondly,an adaptive technique is used to estimate the upper bound information of the attacks mode,and then an adaptive sliding mode control method is designed by the combination of the estimated information.In addition,the security and stability of the dynamical system under two kinds of control methods are proved by stability theory.Finally,the simulation examples validate that the designed robust and adaptive sliding mode control methods can ensure the stability of cyber-physical systems and have good robust performance under the false data injection attacks.(2)On the basis of work(1),to solve the problems of system security control and limited channel bandwidth under the condition that the upper bound of false data injection attacks is known,a robust event-triggered sliding mode control method is proposed.Firstly,by the combination of the event-triggering mechanism and the obtained attacks upper bound information,a robust security event-triggered sliding mode control method is designed.Secondly,the stability theory proves the effectiveness of the proposed method,and the positive minimum lower bound of the event-triggered interval is given to prove that the event triggered control scheme does not exist Zeno phenomenon.Finally,the simulation examples validate that the proposed algorithm can save communication resources and ensure the safe and stable operation of the system.(3)On the basis of work(2),we further consider the problems of system security control and limited communication resource under the condition that the upper bound of false data injection attacks is unknown,an adaptive event-triggered sliding mode control method is proposed.Firstly,for the unknown upper bound of the false data injection attacks,the adaptive technique is used to estimate the upper bound of the attacks mode information,and the adaptive event triggered sliding mode control method is designed by combining with event-triggered mechanism.Secondly,the stability theory is used to prove the feasibility of the proposed method.Finally,the simulation examples validate that the adaptive event-triggered sliding mode controller can ensure the stable operation of the system and improve the utilization of information resource.