Research On High-Speed Railway Track Geometry Irregularity Precise Measuring Based On GNSS/INS Integration System

High speed railway is regarded as the main artery of national economic development.In the past decade,China’s high-speed railway network has made great progress.The mileage of high-speed railway is in the first place of in the world,and the gap between China and other countries is widening.High-speed railway can not only bring short-term economic benefits such as ticketing,but also create long-term social value by accelerating population mobility,and thus promote regional and national economic growth.However,the railway track will gradually deviate from the design value in the use process,resulting in the change of track shape.Under a high travel speed,even small deformation will produce a huge wheel-rail destructive force.In order to ensure the safety of train operation and the comfort of passengers’ ride,the highspeed railway track needs to be carefully measured and adjusted regularly,so that the precision limit between 30 m chord length and 300 m chord length is kept within 2mm and 10 mm respectively.The detection time for track irregularity of existing lines is very limited,usually from 0:00 to 5:00 in the morning.The increase of high-speed railway mileage and speed increase the workload of track detection.At present,the main equipment for track detection is the static detector with total station as the core equipment,whose accuracy is up to standard but the detection speed is too slow,so it is urgent to develop new detection equipment.The combination of Global Navigation Satellite System(GNSS)and Inertial Navigation System(INS)integrates the advantages of each sensor and makes up for their disadvantages.With high-precision,continuous and reliable mobile measurement,GNSS/INS integrated system has the potential to achieve accurate and rapid track detection.Based on this background,this paper has carried out the research of high-speed railway track irregularity precision measurement method based on GNSS/INS integrated system.The main research work is as follows,1)A set of calculation model of high-speed railway track irregularity index suitable for GNSS/INS integrated navigation system is derived,and a calculation method of track deviation of different line types is given.For the case that the track design document is not available,the scheme of obtaining the optimal design curve based on attitude information is adopted.2)In view of the loud noise of the traditional track detection algorithm which directly uses the GNSS/INS position,an improved approach named Attitude Variometric Algorithm(AVA)of the railway track irregularity detection is proposed.Through the derivation of the lateral error formula,the difference between the two algorithms is theoretically compared.3)From the perspective of trajectory domain rather than angle domain,this paper discusses the nature and form of the influence of installation angle on track irregularity detection,and then uses rotation correction to eliminate the system deviation caused by installation angle.The rotation angle is determined by the Total least square(TSL)fitting of similar transformation.4)Using semi simulation data,the accuracy maintenance ability of AVA algorithm during the period of GNSS signal outage is explored,and the performance of AVA algorithm under the condition of GNSS unlock is compared and analyzed.5)The influence factors of GNSS / INS track detection accuracy are investigated,and the corresponding improving strategy is studied.In view of the insufficient accuracy of the conventional Allan variance method in the application of high-precision track detection,the optimization method of inertial navigation process noise based on the repeatability of track deviation is proposed,considering the rigid structure characteristics of high-speed rail.Moreover,the carrier motion constraint model is studied,and the actual accuracy and availability of the vehicle motion constraint information are analyzed.The conclusion is drawn that the effect of dynamic constraint is limited under favorable GNSS condition.The constraint effect under the case of GNSS outage is evaluated by testing the vehicle motion constraint data of different frequencies.Meanwhile,the influence of the introduction of total station on GNSS/INS track inspection is explored,the constraint mode of total station on GNSS/INS is analyzed,and the scheme of deviation constraint of total station is determined.6)The field test of the track is carried out,and the experiments are carried out in Guilin,Guangxi and Inner Mongolia respectively,collecting experimental data of the two groups between which the quality of the track is different.When the track quality is good,the repeatability of shortwave irregularity y is within 0.2mm and 2.5mm respectively in both of the horizontal and vertical directions,while longwave irregularity index is no more than 2.5mm.For shortwave irregularity,the RMS values of the difference of AVA and reference value are 0.3mm and 0.4mm in both of the directions,while for longwave irregularity,the values yield 1.8mm and 2.0mm.In the case of the inferior quality of the track,the RMS values of the external compliance of AVA for shortwave irregularity are 0.18 mm and 0.28 mm in both of the directions,while for longwave irregularity,the values yield 3.4mm and 5.2mm.After applying the total station deviation constraint with 200 m interval,the RMS values of the horizontal and vertical directions for longwave irregularity are 1.4mm and 1.8mm,respectively,which is improved by 75% and 65%.