Design Of Intelligent Measurement System Of Vehicle Overall Dimensions

In recent years,with the development of three-dimensional(3D)imaging technology,structured light imaging has become a very important component in the field of 3D reconstruction of the depth of field,which can be widely used in industrial measurement and other fields.Based on structured light imaging,the measurement system of motor vehicle exterior dimension has relatively wide application range,low requirement for matching environment and low hardware cost.In this paper,we design a set of intelligent measuring system for the size of motor vehicle by using the technique of depth-of-field reconstruction and machine vision.The system can meet the requirements of national standard 21861-2014,and can be used in the detection of motor vehicle Measurement of profile dimensions.Its core content includes three aspects: The first is structural light projection based on random speckle principle.The goal of the design is the single point laser scattering for random multiple scattering by diffusion optical sheet,convolution of scattering results by grating,surface projection matrix to the measured object surface.The second is the structure of light decoding and depth of field acquisition.We extract laser point cloud with Laplace operator,and use two-dimensional cross-correlation algorithm to calculate the correlation of current point cloud information and pre-projection information to determine the current point cloud depth;And the correlation degree between the calibration data to determine the current point cloud depth of field.The third is the motor vehicle exterior modeling.Multi modal mixed Gauss background modeling algorithm to achieve the extraction of vehicle foreground signals,using ICP algorithm to realize the iterative registration of point cloud information,using machine vision algorithms including optical flow tracking,cascade classifier,semi supervised learning method to realize the rough matching point cloud information,according to the national standard of motor vehicle accessories and continue to remove the extraction.At the end of this paper,GPGPU acceleration technology and parallel computing are used to optimize the system algorithm and improve the performance greatly.The related integrated circuit design obtained one national invention patent and the related software obtained two national software copyrights.The pilot test results show that the intelligent measurement system of the motor vehicle outer dimension adopts the pass-through measurement method.The whole measuring process is completed in one minute.A variety of motor vehicle contour length and width measurement accuracy of 1% or 10 CM or less.For the same vehicle repeatability measurement error can be stabilized at 0.5%,fully meet the national standard GB21861-2014 measurement requirements.The current research results have been applied to Tianjin Yichang vehicle inspection station,the research group has set up one set of intelligent measurement system of motor vehicle dimensions at 1 outdoor inspection line,passed the Tianjin Institute of Field measurement test,and get the measurement apparatus permits.As of September this year,it has been successfully operating 3 months and obtain the leaders' praise of Tianjin Municipal Traffic Management Bureau.