Research And Implementation Of Automatic Steering Method Of Track Laying Machine Based On GNSS

The 14 th Five-Year Plan mentions that railroads are the largest transportation mode in the current transportation system,and railroad construction is an important part of the strategic layout of transportation,and requires the goal of achieving intelligent railroads in 2025 and applying Beidou satellite navigation technology to railroad construction.The accuracy of railroad track laying is crucial to the safe operation of trains,and with the increasing number of railroad construction projects,the original manual track laying needs to be upgraded to automated track laying.In order to enable better application of satellite navigation technology on top of automatic steering of track laying machines,the accuracy and stability of speed measurement and positioning of satellite receivers need to be improved.This paper firstly introduces several basic observation quantities and differential relative positioning principles in satellite positioning,and then modifies the satellite receiver velocimetry and positioning model by using the geometric feature information of railroad foundation and track median,and conducts a comparative analysis with other methods.Finally,a track laying machine automatic steering system is developed based on this,and field tests and results analysis are conducted.The main research includes the following points:1.The Doppler relative velocimetry method with constraint is proposed,which first establishes the inter-station Doppler differential model to eliminate part of the common error,and then adds the skyward velocity constraint according to the characteristics of railroad track elevation changes minutely,which improves the accuracy and stability when velocimetry.2.The additional centerline information-assisted localization method is proposed,using the existing orbital centerline coordinate data,fitting and combining to establish the linear constraint equations,and then integrating them into the Kalman filter model of the mobile station to participate in the localization solution.When the satellite signal is partially occluded,the ambiguity fixation success rate is improved by 14.1%compared with the positioning results without median information assistance.3.A set of automatic steering system for track laying machine is developed,including two parts: the receiver of the reference station and the receiver of the mobile station.The base station converts the original observation data into differential data after obtaining it,and then transmits it to the mobile station wirelessly.After receiving the differential data,the mobile station decodes it and outputs the speed information and centerline offset to the PLC controller through the serial port,which in turn controls the hydraulic steering system and throttle size of the track laying machine.Finally,the field test and result analysis were carried out,and the system can meet the construction requirements of railroad track laying.