Research On Demodulation Method Of Sensing Signal Of Fiber Bragg Grating Array For Positioning And Speed Measurement Of Maglev Train

With the rapid development of maglev train technology in China,higher requirements are put forward for the accurate acquisition of key information such as train speed and position.At present,the maglev train mainly uses the traditional electrical monitoring method for positioning and speed measurement.This method depends on the stable external environment and is vulnerable to electromagnetic interference,so the measurement accuracy is limited.Optical fiber sensing positioning and speed measurement technology has the advantages of good stability and anti electromagnetic interference,and can realize long-distance and distributed monitoring through networking multiplexing.However,the application of existing optical fiber sensing technology in rail transit positioning and speed measurement is mostly in medium and low speed scenarios.In order to realize the positioning and speed measurement of the train in the state of high-speed movement,this paper proposes a signal demodulation method of the maglev train positioning and speed measurement system based on Bragg fiber grating(FBG)sensor array.The main research work of this paper is as follows:(1)Aiming at the technical problem that it is difficult to achieve accurate positioning and speed measurement when the maglev train is running at high speed,based on the fiber Bragg grating array positioning and speed measurement sensing scheme of maglev train,a high-precision positioning and speed measurement demodulation method for Maglev Train under high-speed operation is proposed,the mechanism of positioning and speed measurement through magnetic induction is studied,and the demodulation system is built.(2)Based on the positioning and speed measurement mechanism of maglev train and the construction of demodulation system,the corresponding signal demodulation methods are studied.The grating position and wavelength information demodulation is realized through the adaptive S-G(Savitzky Golay)filtering algorithm and the grating fast addressing algorithm proposed for the nonlinear scanning of frequency scanning light source in high-speed system.Considering the time and accuracy,a better improved centroid detection peak finding algorithm is proposed.The solution method of speed position information is designed,and the feasibility of positioning and speed measurement under the condition of high speed is analyzed(3)Based on the research on the demodulation method of maglev train positioning and speed measurement signal,according to the functional requirements of positioning and speed measurement,the demodulation implementation of high-speed speed speed measurement and positioning system is designed,the system framework of B / S(Browser / Server)architecture is studied,the functions of specific modules such as data acquisition,data processing,data storage and front-end display are realized,and the method of improving data processing efficiency through ring queue combined with multi-threaded parallel mode is studied,A remote monitoring system for maglev train speed measurement and positioning is constructed,which integrates the functions of real-time position state display and data processing.(4)The wavelength demodulation performance and stability of the system are tested and analyzed.The rotating motor magnetic field alternating experiment is used to verify the speed measurement and positioning principle,and a high-precision linear displacement experimental platform is built to test the speed measurement,positioning and demodulation performance of the monitoring system under the condition of uniform train movement.The experimental results show that the overall positioning accuracy of the system reaches 2cm and the speed measurement error is within ± 1%.