The Research On Node For Monitoring Strain And Temperature And Humidity Of Continuous Welded Rail

Railway transportation is based on the rail and seamless rail is widely used in the high-speed railways. Continuous welded rail is limited to expand contract in axial direction, so the internal temperature stress comes into being when the temperature changes. When the internal stress of the rail is greater than resistance of the fasteners and rail track bed, the rail will crawl, which will have an effect on the stability of CWR. Therefore, it is very necessary to get the rail temperature, stress and other state information quickly and rapidly for monitoring the stability of the rail.This article designed a kind of long-distance and real-time monitoring node to monitor temperature, humidity and strain of the rail with a combination of sensor technology, embedded technology, wireless communications technology, optimization algorithm and so on. The monitoring node can achieve long-distance and real-time acquisition and wireless transmission of rail’s state information, then the data can be used to analyze the running state of the rail in order to discharge the rail stress. This article focuses on the design of hardware and software of the monitoring node.After analyzing the function of the monitoring node, the paper finished the design of the node hardware. In the principle of low power consumption, small size, high precision and anti-jamming, the node is designed modularly and it is made up of a power supply unit, a communication unit and a sensing unit. The power supply unit which is made up of a protection circuit, a switching regulator circuit and a linear regulator circuit design provides stable and high quality power output. According to the set parameters, the sensing unit can complete the collection and delivery of rail strain, temperature, and humidity data. The communication unit exchanges data with gateway by wireless transmission.The node software was designed on the basis of the node hardware. The node software includes not only the design of the basic functions about data collection and transmission, but also the design of digital filter and data compression.The nodes had been carried out a series of experiments. the temperature and humidity properties experiment was carried out to measure the accuracy of the temperature and humidity that the node collects; the high and low temperature experiments on node’s strain collection show its temperature and time drift characteristic; the electromagnetic interference experiment was conducted in order to test the reliability of data transmission between nodes and gateway. Monitoring nodes were installed in a high speed railway experimental field and tested for a long time, the result of the experiments shows that node are able to collect the real-time information of the rail stably for a long term.