A Lidar-based Measuring Instrument For Vehicle Profile Size

Overload and overlimit transportation is the first killer of the road,which is easy to cause traffic accidents and seriously endangers people’s life and property safety.In order to strengthen law enforcement monitoring capacity and ensure traffic safety,this paper mainly research and development a lidar-based measuring instrument for vehicle profile size.This equipment is mainly used in the test station of vehicles to measure the profile size of vehicles.On the one hand,due to the need to measure the vehicle at low speed,there may be slight deflection,tilt and other situations in the process,and there are various interferences in the environment,so there is a large error in the measurement value calculated simply with the original data.Therefore,it is necessary to denoise the original data and study specific methods to get accurate results.on the other hand,some kinds of vehicles need special methods to measure.In addition,after the installation of the measuring instrument,the lidar related parameters need to be calibrated to ensure the accuracy of the original data.In view of the above problems and requirements,the key technologies in the lidar-based measurement instrument for vehicle profile size are studied.The main work and achievements are as follows:(1)The calibration method of lidar system is studied.Firstly,an automatic calibration method of lidar based on scanning altimetry is proposed to calibrate the installation height and center angle of each lidar.Then,a calibration method of lidar system based on cubes is proposed,which can correct the scanning plane of lidar by continuously scanning the cubes.Finally,the influence of system calibration on measurement accuracy is demonstrated.(2)The measurement method of vehicle profile size is studied.Firstly,filter the original data,then select a specific calculation method according to the types of vehicles.Finally,considering the deflection of the vehicle driving direction will bring errors tothe measurement,a k-frame calculation method has been proposed to eliminate the errors of measurement caused by the deviation angle between the vehicle and the central axis when the vehicle is moving forward,and at the same time to overcome the synchronization requirements of left and right lidar and remove some noise data.(3)The method of drawing vehicle profile and 3D model is proposed,and the 3D point cloud data set of large vehicle is constructed.Considering the large size of the inspected vehicle,it is difficult to find out the out of limit part of the vehicle in time and rectify it only by the measurement results,a 3D model rendering method based on 3D point cloud and Open GL is proposed,and the collected 3D point cloud data of different vehicles are classified and sorted out,and a 3D point cloud data set is proposed.