Research On End-To-End Delay Of TTE-based Networked Control System

The Networked Control System has integrated the calculation process with the physical process.Because of the advantages of easy expansion,reliability,flexibility,and less wiring,NCS has become a research hotspot in the academic and industrial cir-cles.The accurate timing and error-free communication requirements of the networked control system cause time-triggered Ethernet and other deterministic protocols to dom-inant the field of NCS.However,due to the introduction of the TTEthernet network,many new problems such as network delay,transmission jitter,and packet loss occur in the system.The main achievement of this dissertation is to analyze the characteristics of net-work delay in networked control system,to design the end-to-end delay analysis algo-rithm as accurate as possible and buffer dimensioning strategy,and to study the method of analyzing and modeling the network delay by using simulation tools.The following outlines the research results:1.The research of the concept,structure and characteristic of NCS,as well as the trends of the application of TTEthernet and other deterministic protocols in this field.The main problems that occur when the time-triggered Ethernet protocol is applied in the system are given and a survey of NCS research work is analyzed.And some useful research aspects are summarized and established.2.The composition of the end-to-end delay in the NCS.By analyzing the composi-tion of the network delay in the system,the concept of end-to-end delay is defined,and the reasons for the fonnation of the end-to-end delay are analyzed in detail.3.The FWA(Flow-grained Worst-case end-to-end delay Analysis)end-to-end de-lay calculation method is proposed.This method takes the flow as granularity and calculates the delay of the flow transmitted from the source node to the desti-nation node,considering the interaction of the time-triggered flows and the rate-constrained flows from the same and different input links.Finally,the compar-ison experiments show that the FWA analysis method can significantly improve the accuracy of the calculation,and the time complexity is low.4.The FBD(Forward Buffer Dimensioning)buffer dimensioning scheme for the switch nodes(switches)in the network is proposed.First,the scenario when the buffer occupancy gets the worst case is analyzed.In order to calculate the occu-pancy of the node buffer when the worst case occur,the method for calculating the number of frames at the maximum arrival rate and the service algorithm to minimize the transmission frame rate are studied separately.And through exper-iments,the effectiveness of the strategy was verified.5.The extension of TrueTime and the simulation of the TTEthernet-based NCS.A sample TTEthernet configuration is modeled and simulated using the TrueTime library and extended models.Finally,the simulation results are compared and analyzed with the results of the mathematical analysis algorithm.