Study Of 3D Detection System Of Automobile Contour

With the construction and improvement of road network,automobile transportation plays a more and more important role in the logistics industry.However,some vehicle owners illegally modify vehicles with the purpose to overload,which has seriously threatened public security.Therefore,regular detection of the dimension parameters of vehicle contour can eliminate illegal modification to some extent.Traditional methods,such as the tape measurement,belong to manual measurement,which are time-consuming and laborious,and may cause large errors due to improper operation.They cannot meet the requirements of automation,high precision and high efficiency.This paper,based on the 2D laser scanner,proposes a 3D contour detection system,which uses three laser scanners to collect the contour information.Two scanners are installed on both sides of the measurement area to obtain the side section data and the last one is installed in front of the vehicle to obtain its length data.This paper also puts forward the curve fitting method for discrete points based on the data of the vehicle head,in order to solve the problem that some feature points are difficult to be determined during the vehicle length calculation.To solve the noise problem caused by accidentally scanning the discrete points in data processing,this paper presents the improved stochastic filtering algorithm based on the change trend of the vehicle shapes to repair the problem data on the scanning line.To avoid the scanning deviation in practice,this paper comes up with a hardware calibration method based on the three-dimensional coordinate system,by which the scanning plane of the three scanners form a “T” structure and the collected data can be spliced into the coordinate system.In addition,a 3D contour drawing method based on frame matching is proposed as well.The results of repeated tests of different vehicle models show that the system can measure the outer contour dimension and draw the 3D contour at the speed of less than 5km / h.The system measuring error of the vehicle outer contour dimension detection is less than ±1% or ± 20 mm,which meets the requirement of “Items and Methods of Motor Vehicles Safety Technology Inspection”(GB21861-2014).These findings are of great significance to realize the automated detection technology of vehicle outer contour dimension and prevent overload from the source.