Research And Development Of A Safety Test System For Vehicle Body Structure

Vehicle safety is the most important technical target. Based on FMVSS214, FMVSS216 and vehicle crash principle, a safety test bench for vehicle body structure is researched and developed in this thesis. Meanwhile, using the digital image processing technology and photogrammetry, a 3-D image measurement system for the bench is developed. Using this system, the combination of qualitative and quantitative analysis for vehicle crash test can be reached, which is of great significance to research and enhance vehicle safety. The main jobs of this thesis are as follow:1. Bring up the overall design scheme of the test system. The system constitution and its realized key technologies, as well as the working principle are interpreted in detail.2. Complete the stiffness verification of the test bench and the stability analysis of the vehicle adjustment and fixing device for the roof crush test using FEA. Result shows the rationality of the bench's structure design.3. Establish a complete camera model with distortion correction and fulfill the 3-D spatial coordinate measurement of the vehicle body mark point. The camera's internal and external parameters are calibrated using two-step method. Based on the established camera model and using least-square algorithm, the 3-D spatial coordinate measurement of the mark point is realized. Through the given spatial points measurement experiment, the correctness of the established camera model is proved. 4. Establish the algorithm for mark point recognition and its central image coordinate extraction. Image background difference technique is employed to realize the quick recognition and extraction of vehicle body mark point. On this basis, the image is under graying and binarization process. In order to eliminate the interference of noise point, the mathematical morphology based noise reducing algorithm is designed to finish the image pretreatment process. After that, the centroid-based subpixel localization algorithm is used to accurately extract the mark point's image coordinate. When it comes to the analysis of the serial images from the crash test video, the correlation method of gray-based image matching is applied to track the mark point in the serial images and extract its image coordinate, which form the basis of the following 3-D spatial coordinate measurement of the mark point.5. Complete the design of image measurement system hardware. On the platform of VC++, the image measurement system software is developed based on class seal technology. The system software include the following modules: video file playing and replaying, video file format transformation, image processing, image measurement and the main program.Through the analysis of a specific vehicle crash test, the test system is proved to reach the design requirement of reliability and accuracy.