| Network control system(NCS)integrates control system theory,modern communication technology and computer technology,which is one of the national key strategic development targets.However,in recent years,due to the frequent occurrence of network security events,how to improve system security is the key issue of NCS research.Among the various attacks,Denial of Service(DoS)attacks are easy to be implemented on a large scale and have a great impact on NCS.Therefore,this thesis conducts an analysis and research on the predictive control problem of NCS under DoS attack.The main contents of this thesis are as follows:For the disturbed NCS under two-channel asychronous DoS attacks,an eventtriggered predictive control method is developed.Taking the influence of the dualchannel asynchronous DoS attacks into consideration,a predictive control sequences is generated by the predictive controller at every successful transmission instant.When the system suffers DoS attacks,the predictive control sequence can be used to compensate for the lost control signal.Combined with NCS system model,predictive control method and event triggering mechanism,the predictive control closed-loop system is constructed.A sufficient condition for the system to be uniformly ultimately bounded is derived and the controller gain design method are obtained.At last,a numerical simulation illustrates the effectiveness of the developed method.For the NCS whose states cannot be directly measured,a dual event-triggered predictive control scheme is designed in the presence of dual-channel asychronous DoS attacks.Considering that the state of the system is unmeasurable,the Luenberger observer is used to estimate the actual states of the system.Combining observer and predictive controller and dual event-triggering mechanism,a closed-loop system of event-triggered predictive control based on observer is established.Based on Lyapunov stability theory,the sufficient conditions for maintaining the asymptotic stability of the system are obtained and the joint design method of controller gain,observer gain and event-triggered matrix are derived.At last,the numerical simulation of spacecraft system illustrates the effectiveness of the proposed method.Finally,based on the semi-physical experimental platform of the Quanser couple-tank liquid level control system,this paper illustrates the effectiveness of the proposed method by designing experiments.The results show that the event-triggered predictive control method in this thesis can effectively compensate for the packet losses caused by two-channel asynchronous DoS attacks,and reduce network resource while ensuring system performance,and has better anti-disturbance ability. |
