Study Of The Motor Vehicle Outline Size’s Measuring System

Motor vehicles have brought us great convenience and economic benefits, but also brought us some trouble, such as traffic congestion, traffic accidents, environmental pollution, etc. The problems caused by traffic accidents are particularly serious. The statistics show that one of the major causes of the traffic accidents is the over-load and over-limit of vehicles, most of which were refitted without permission for their own interests. Therefore, the measurement of vehicles outline size can prevent the over-load and over-limit phenomenon to some extent.At present, the detection of refit and oversize have to rely on the manual measuring method, which has not been able to meet the need of modern automated detection. In this paper, a motor vehicles outline size’s measuring system based on 2D laser range finder is designed. The vehicle outline information is collected by three laser range finder which is fixed on the gantry. The upper-computer software written by C++ language, is developed in Visual Studio 2010 and the user interface is developed by MFC. The communication between upper-computer software and the laser range finder is accomplished by using C/S mode, TCP/IP protocol. The designed system can accomplish the function of data acquisition, processing, result output, data preservation, etc. The designed system has realized the automatic measuring the size and drawing the outline of the vehicle. This paper presents a two-dimensional laser range finder calibration scheme, which can convert and correct the data measured by the laser range finder in the X, Y direction of the established rectangular coordinate, which makes the measured data can be matched more accurately and improve the measurement accuracy of the system.Many experiments of various types of vehicles were carried out to verify the function, accuracy and stability of the system. The results show that the designed system can measure the size and draw the outline of the vehicle when the motor vehicle at a low speed of less than 5km/h. A single measurement can be accomplished in 15 s, the error is plus minus 35 mm and the repeat error is plus minus 10 mm. The measurement system can meet the requirements of “Motor vehicle safety technical inspection items and methods”(GB21861-2014), which the measurement error of the motor vehicle size should not exceed plus minus 1%(registered vehicles) / plus minus 2%(in-use vehicle) or plus minus 50 mm. It has practical significance to realize the automation and intelligence of the automobile testing line, to control the occurrence of the over-load and over-limit phenomenon, to strengthen the management and to improve the traffic safety.