Study On Body Spot Welding Robot Path Modification Based On Stereo Vision

White body is the carrier of automobile body parts，and is the important part of the car,White body welding is one of the most important process in the process of motor vehiclemanufacturing. Due to the resistance spot welding in the process of production: highlycentralized power, plate deformation, high production efficiency，so it is especially suitablefor the welding of thin-wall parts, is widely used in the automobile body welding. Themovement of the white body spot welding robot is according to the path of the proceduresprescribed, it is fixed unless the program is changed. The shape of the welding parts fixtureis changed because of the stress or the displacement of welding parts is changed because ofmovement. Welding robot is still in accordance with the original path, leading to the actualsolder joints is not consistent with theory of solder joint position.Resulting in the solderjoints defect, such as the solder joint deformation, without penetration, burn through, unableto meet the requirements of the theory of strength of solder joints, affecting the weldingquality of the vehicle.Traditional solder joint quality inspection methods have destructive testing andnondestructive testing destructive testing is to tearing the solder joint of the sampling body, itcan reflect the quality of the white body intuitively and comprehensively. Non destructivetesting method contains carved inspection and visual inspection, It can be relatively timelyfeedback welding quality, for the analysis of field engineers judgment problem, optimize thewelding process and control the production process of adjustment, It has advantages of highefficiency and low cost. But the results are greatly influenced by subjectivity and experienceability of person, it cannot give an objective standard.Now days，Ultrasonic nondestructive detector used in the detection of solder joints,high working efficiency, and the test results intuitive easy to analysis, but the abovedetection method are testing the spot welding when the spot welding were done,even detectthe solder joint quality problem, also can’t to change of solder joints, and the above methodand low efficiency, high cost, unable to realize the on-line detection, so the white bodywelding process urgently need a new intelligent welding robot that can carry on the automatic testing and welding path correction, reduce weld defects of solder joints in theend.This paper established a body welding robot path correction system based on computervision, with the door frame as an example to test. First expounds the system structure ofwelding robot, camera to obtain the target image. To deal with image, obtain the position ofthe welding parameters and compared with the theoretical position, if there is a deviation,deviation is calculated, through single chip microcomputer control, realizes the completecompensation amount on welding robot.The main research contents and steps are as follows:1. Using toolbox on two camera calibration, get inside and outside the parameters ofthe camera. using the camera of calibration to photograph the target area, the image areprocessed by the gray-scale adjustment, noise reduction, image pixel binarization processing,skeleton extraction and so on, at last the target point coordinates is obtained by the Hough.2. The three-dimensional space coordinates of target points are obtained accord to theinternal and external parameters of camera and the image around the coordinates of thecorresponding target. The coordinates of the point target is curve fitting to getting the spacecurve equation, and then the curve is rotation to the welding plane parallel by the curverevolving, principle, and then calculate the size of the amount of compensation.3. Using computer programming control welding robot based on the compensationamount, welding torch position adjustment before the welding, making to the weldingposition closer to the final or are in the ideal position.Study the significance of this paper is to improve the accuracy of body position of spotwelding and the accuracy and speed, thus reducing due to the welding position is notaccurate spot welding problems, improve the quality and speed of the car body welding, butalso cannot achieve the actual welding position and welding position theory coincide, needfrom the experiment of hardware equipment, environment, and image processing methodthree aspects for further optimization..