Research On Dynamic-priority And Feedback Based Transmission Scheduling In CPS

Cyber-Physical System(CPS)is a new kind of intelligent complex system integrating computation,communication and control technology.CPS has deeply integrated of the information and the physical resources,and many problems brought by the joining of network.The characteristic of high complexity,large amount of information transmission and instability of network of the system will have serious influence on the control performance of the system,so the strategy of the network transmission scheduling will affect the overall performance of the system directly.Firstly,this thesis reviews the related theories and the research status of CPS,compares it with the traditional application systems,and discusses the classification of network in CPS and several key factors affecting the network performance.Based on which,the problem to be solved in this thesis is raised——how to improve the utilization rate of network and ensure the control performance of system when the network resource is limited and the transmission performance is unstable.Secondly,the application of traditional open-loop scheduling strategy in CPS is studied and the advantages and disadvantages of the traditional static and dynamic scheduling algorithm when they are applied in CPS by simulation experiments are analyzed.Based on which,an integrated feedback transmission scheduling strategy is proposed.This strategy can adjust the priority of the control loop and the sampling period respectively according to the dynamic change of available resources of system.For the priority adjustment,the dynamic priority allocation algorithm based on multi-characteristic parameters is applied.The priority of the tasks in this algorithm is determined by the control performance and the tasks deadline,these two characteristic parameters.While for the sampling period adjustment which is based on currently available network resources,sampling period is dynamically adjusted according to the demand of the current control performance.So the overall control performance of system can be ensured when the network resources are limited.Finally,simulation analysis is made for strategies proposed above by using the toolboxes of Matlab/Simulink and Truetime.A CPS simulation model comprising of several control loops is established and the superiority of the proposed method is validated by comparing the strategy proposed in this thesis with traditional algorithm.