Investigation Of Rail Axle-Counting Systems Based On Matched Fiber Bragg Gratings

Track traffic photoelectric axle-counting systems based on matched Fiber Bragg Gratings are mainly used for train positioning. From the principle of conventional fiber Bragg grating (FBG) sensors and according to the proposed strain sensing method using two matched FBGs and theoretical analysis of track strain distribution under load we detect the stress of Paste the grating area on the rails, after the measurement data processing and analysis the inspection and free range of the train are completed. The axle-counting equipment using in railway signaling system are objective to improve traffic safety technology and the efficiency of rail transport.Track traffic photoelectric axle-counting systems based on matched Fiber Bragg Gratings is investigated from the two aspects of theoretical analysis and experimental verification in this paper. Firstly, the principle of conventional fiber Bragg grating sensors are introduced, according to theoretical analysis of track strain distribution under load we design a track sensor that can detect the local axial strain. At the same time, the principle of Track traffic photoelectric axle-counting systems based on matched Fiber Bragg Gratings. Then, matched grating demodulation for an intensity demodulation we give the system the hardware design of the overall framework. In order to facilitate system maintenance and upgrading of equipment, this axle-counting system is designed for three parts:motherboard card module,module from the board and template module, on each board has a LPC1768 ARM microprocessor chip. Simultaneously, system circuits have increased circuit protection in each module features, the motherboard card and slave card communicate through I2C bus, the host receives information from the slave cards, then passes to the host computer. Finally, a lower computer programs are written with Keil uVision3 development tool. Modular software design methods are adopted and this design is conducive to software code debugging,maintenance and upgrades.The available results are as follows:After the train load simulation, track traffic photoelectric axle-counting systems based on matched Fiber Bragg Gratings receive rails strain information laying a Fiber Bragg Grating sensor. The data results of motherboard card processing on the Lower computer are passed to the host computer (PC) by Ethernet. After drawing, the periodic strain curves of track strain distribution under load are gained, this curve and the detector on the Lower computer receiving the light intensity is one to one relationship, the light intensity I is directly reflected in the strength of the tracks of the strain information, the appropriate threshold parameter is selected and the curves are be shaped so that we can obtain whether the train tracks and the number of passing train wheel, the function of train axle-counting is correspondingly achieved. Results under different environmental temperatures and load frequencies indicate that the matched-FBG approach can effectively solve the temperature and strain induced cross sensitivity problem, four-channel data acquisition were normal, therefore it can meet requirements for axle-counting in rail systems. Such design may be a good candidate for constructing WIM systems as well.