Research On Train Ethernet Network Communication Real Time Based On TRDP Protocol

Railway is the main mode of inter-city traffic.High-speed EMU is the first choice for national travel because of its convenient,fast and comfortable characteristics.In recent years,China's high-speed rail industry has developed rapidly.The Fuxing train,which has completely independent intellectual property rights,represents that China's EMU manufacturing technology has reached the world's leading level.With the development of train equipment manufacturing technology and network technology,traditional TCN network can not meet the needs of diversified network services.Since 2012,IEC has promulgated new standards of train communication network based on ethernet.However,due to the shortcomings of reliability and real-time performance of ethernet,it may affect the real-time control performance of trains and threaten traffic safety.Therefore,it is necessary to study the real-time performance of the train ethernet communication network and to improve the real-time performance of the network.This paper is to carry out in-depth research on these two points.Firstly,through the in-depth understanding of train communication network framework and network communication mechanism based on TRDP,this paper theoretically analyses and studies the causes and effects of network-induced delay.In order to obtain accurate delay data,a communication monitoring software based on TRDP protocol stack is developed on computer as a tool to measure delay.The validity and correctness of the software are verified by testing.Then,by building a train Ethernet test platform,simulating the control signal and network load according to the actual working conditions of the train,the delay of network data frame is measured by using computer equipped with communication monitoring software and accompanying equipment.Then the system delay data under different task cycles and network load rates are tested.Based on the obtained delay data,the delay characteristics of train ethernet under different conditions are studied,and the method to reduce the system delay is obtained.When analyzing the data,it is found that in the experimental group with high network load,the delay of message data is large.To solve this problem,the queuing delay caused by data passing through network devices is studied.An optimal priority scheduling method based on default priority scheduling is proposed.The network calculus method is used to calculate the upper bound of end-to-end delay under default priority scheduling,first come first served scheduling and optimal priority scheduling.The calculation results show the superiority of the optimal priority scheduling method.Finally,the validity of the optimized priority scheduling method to improve the real-time performance of train system is verified by experiments.