Development Of Orbital Mobile LiDAR Measurement System Based On 5G Communication

In view of the background of “new infrastructure” construction such as digital twin city,smart city rail and underground realistic 3D,which requires high accuracy of urban rail spatial information data,this paper takes the measurement principle of mobile measurement system as the theoretical basis and researches the mobile Li DAR measurement system applicable to urban underground rail transportation.The existing rail mobile measurement system mostly operates in the mode of hand-push travel,line scan data acquisition mode,and is equipped with expensive posture positioning module,which has the disadvantages of low acquisition efficiency,insufficient data accuracy,high cost and bulky body,etc.This paper develops an economical automatic travel Li DAR measurement system applicable to the remote transmission of spatial data in underpass tunnels,which realizes the high-precision total attraction of underpass tunnels cloud data acquisition at regular intervals and remote real-time transmission.The main research work of this paper is as follows:(1)Summarizes and outlines the current research status of existing orbital mobile Li DAR measurement systems at home and abroad,and describes the background significance of the orbital mobile Li DAR measurement system development and the social benefits it brings.By comparing and analyzing the integration hardware,data acquisition method,data acquisition accuracy and other system indexes of each orbital mobile measurement system,we summarize the optimizable solutions of the existing orbital mobile Li DAR measurement system and clarify the research direction of this paper.(2)An economical rail mobile measurement system based on network communication applicable to subway tunnels is designed and developed.The system consists of a vehicle subsystem composed of an autonomous traveling rail cart and Li DAR,a network communication subsystem based on 5G communication module,and a massive data cloud service subsystem.The whole system uses an embedded computer as the control center to realize the automatic travel of the orbital trolley and the panoramic scanning of Li DAR,and to realize the real-time transmission of Li DAR data based on TCP/IP network transmission protocol.The mobile measurement system is not equipped with inertial guidance as the main cost source of position positioning module,but changes the mobile measurement of Li DAR line scan to panoramic scan,the change of scanning mode reduces the integration cost and improves the data accuracy.The Li DAR in panoramic scanning mode is mounted on a rail car that can be parked at regular intervals to realize the function of regular interval data collection of the measurement system,which changes the tedious process of moving stations in traditional ground LIDAR measurement.(3)A global alignment method based on CPIII control points with multiple iterations is proposed for the point cloud alignment of underpass tunnels.The method takes the CPIII control points of the underpass tunnel as the constraint base for global alignment,and takes the stations between each pair of CPIII control points as a partial whole for multi-view point cloud alignment.After the completion of the local global alignment,the global control of the CPIII control points completes the overall alignment.The research shows that the 5G communication-based orbital mobile Li DAR measurement system designed and developed in this paper can be applied to the whole point cloud acquisition in underpass tunnels,which not only can complete the automatic point cloud data acquisition,but also can realize the autonomous remote data transmission in real time without data loss.The global holistic alignment method based on CPIII control points with multiple iterations can realize multi-view point cloud alignment of narrow underpass tunnels,and its alignment results are an order of magnitude more accurate than the point cloud data from line scan mobile measurements.