Research On Fiber Bragg Grating Sensor For Maglev Train Positioning And Speed Measurement

Location and speed measurement technology is one of the core technologies of high-speed trains and other rail transit vehicles,which plays a vital role in ensuring the safety of train operation during running,and is the key to building a reliable train safety system.At present,maglev train positioning and speed measurement technology mostly use relative positioning and absolute positioning based on the electrical system.Due to the influence of external electromagnetic interference and low transmission rate,the measurement accuracy is limited,which cannot meet the requirements of maglev train positioning and speed measurement.Given this,this paper makes use of the advantages of Fiber Bragg Grating(FBG)sensing technology to deeply study a maglev train positioning and speed sensor based on weak Fiber Bragg Grating.The main content of the paper is summarized as follows:(1)Based on the analysis of the advantages and disadvantages of existing high-speed maglev train location and speed measurement technologies at home and abroad,aiming at the current demand of maglev train location and location,a research idea of high-precision maglev train location and speed measurement fiber grating array sensor based on the alternating magnetic field is proposed.Combined with the sensing and signal demodulation principle of fiber grating,the mechanism of magnetic levitation train positioning and speed sensor based on fiber grating array is studied,and a high precision positioning and speed measurement method based on wave peak and wave valley counting are proposed.(2)Based on the principle of elasticity,the sensitivity mechanism of maglev train positioning and speed measurement is analyzed,and a snake-like elastic sensitive structure is designed to form a magnetic induction FBG sensing unit with a cylindrical induction magnet.Finite element simulation software was used to analyze the effects of resonance frequency and response sensitivity of magnetic induction FBG strain sensor on sensor performance,and the relationship between response frequency and sensitivity of magnetic induction FBG strain sensor and sensor structure was obtained.(3)The mechanism of the vehicle excitation magnet module array on the track positioning speed sensor cable is studied.Through theoretical analysis and simulation,combined with the idea of the Halbach Array,a kind of arrangement mode of vehicle-mounted excitation magnet module Array which is suitable for the positioning and velocity measurement method in this paper is proposed.Simulation software is used to simulate the vehicle-mounted excitation magnet module array,and the simulation results show that this arrangement can effectively enhance the external magnetic field intensity,and can meet the requirements of high-precision train positioning.(4)A maglev train positioning and speed measurement system based on ultra-low reflectivity fiber grating is built by combining the vehicle-mounted excitation magnet module array and track fiber grating sensing cable.The accuracy of the proposed method and the response characteristics and sensitivity of the magnetic induction FBG strain sensor are verified by the field maglev train motion simulation test.Experimental results show that the system can achieve the positioning accuracy of 2cm at low speed,and the average error of measuring speed is controlled by ±1%.