Design And Implementation Of Vision Four-wheel Aligner’s Calibration System

Computer vision measurement technology is a measurement technology, which has many features such as low cost, high accuracy, high speed and robustness. The binocular stereo measurement technology also has wide prospects which can be used in medicine, agriculture, manufacturing, aerospace and other fields.This system is a calibration rack-based and calibration platform-based calibration and measurement system. It is designed to provide reliable cameras and system parameters for vision four-wheel alignment system. It is different from the vision four-wheel alignment system. The system includes infrared subtraction method, camera calibration, image processing and binocular stereo calibration technology. It has some features such as high accuracy, anti-interference, simple operation. The system includes camera snap module, image processing module, Camera’s parameter calibration module and system’s parameter calibration module.For the big distance between the cameras in the calibration field, the system uses a binocular two targets stereo calibration method.The calibration rack consists of two targets and a rigid body which connects the two targets, Use subtraction method to capture images of the calibration targets on both ends of the calibration rack in designated locations and save the images for later action.The method of image processing module could obtain the center coordinates by extracting the centers and sort the center coordinates and substitute ordered sequence; The method of the system’s intrinsic parameter calibration module is an improved Zhang’s calibration. The checkerboard targets of Zhang’s calibration method are taken place by circular infrared targets. The method substitute ordered sequence into Zhang’s calibration. The method can improve the accuracy greatly, and has strong anti-interference capability. The system’s parameters’ calibration module of the system substitutes the ordered sequence into binocular stereo dual target calibration model and the system parameters of the system are solved.In this paper, I did the demand analysis of visual four-wheel alignment calibration system, and designed the details of each function module. The paper gives operating procedures of calibration, image acquisition module, image processing module, camera parameters calibration module, the system parameter calibration module. The paper elaborated and solved the issues of center extraction and sorting, which were encountered in the development processing. The end of the paper elaborates unit testing, integration testing, validation testing and system testing techniques. The paper gives the test cases, to system security and system performance as examples, and shows the test results and the experimental results then came up with deficiencies and improvements.Finally, with regard to the directions of further research were discussed.