Research And Application Of High-Precision Train Positioning Method Based On Beidou/Inertial Navigation System/Odometer

China already has largest high-speed rail network in the world.As of the end of2020,the high-speed rail mileage has reached 39,000 kilometers,and the total railway mileage has reached 146,000 kilometers.The huge railway network puts forward strict requirements for train positioning.The reliability of train positioning is related to the safety of people’s lives and property.Traditional train positioning methods have high cost or poor accuracy.It is urgent to explore and study new train positioning methods.The train positioning method based on GNSS is the current hot spot,but the train cannot use satellite positioning in the signal obscured area,and additional equipment is needed to achieve seamless positioning in a complex environment.With the gradual improvement of the Beidou Navigation Satellite System(BDS),this paper studies the railway environment vehicle positioning method based on the comprehensive use of BDS,inertial navigation,odometer,in order to achieve continuous high-precision,stable and reliable train positioning.This article establishes the overall idea of "positioning + orbit determination",that is,in areas with good satellite signals,use BDS-3 PPP-B2 b signals to perform Precise Point Positioning(PPP)to achieve high-precision positioning;In the signal obscured area such as train stations,dead reckoning with odometer is used to realize the positioning of trains in complex environments;comprehensive use of map matching,IMU instantaneous status information,etc.to obtain train lane change information to achieve accurate and reliable train orbit determination.The mathematical model and observation equation of PPP are studied,the source of satellite positioning error is analyzed,and the signal structure of BDS-3 PPP-B2 b is studied,and the high-precision positioning of trains based on BDS-3 PPP-B2 b signal is realized.Through accuracy comparison,a mathematical model with GPS L1 and L2 frequency signals,and BDS B1I+B3I as the observation signals is established.Experiments show that,in the railway environment,the BDS-3 PPP-B2 b can achieve decimeter-level positioning.The positioning principle and error source of the odometer are studied,the distance information processing of the satellite signal obscured area is analyzed through data statistics,and a positioning method based on the BDS and odometer fusion with the aid of high-precision orbit maps is proposed.Through the error compensation analysis of the odometer,the error of the odometer in the dead reckoning in the station is weakened,and the continuous positioning of the satellite signal obscured area positioning is finally realized.The characteristics of railway turnouts and lane change states are studied,and the instantaneous state mutation information of the angular velocity of the IMU equipment fixedly connected to the train is analyzed when the train passes through the turnout.Accordingly,based on the principle of the IMU and the characteristics of the strapdown inertial navigation system,a filter solution method for train lane change based on the instantaneous information of the inertial measurement unit(IMU)is proposed,and the lane change judgment based on the difference of the mean angular velocity is designed.The method accurately extracts the train lane change information,and the experiment verifies the high reliability and accuracy of the method.