The biprism stereo vision system was applied to measure the bead profile in the gas metal arc welding (GMAW), which consists of the optical filter, biprism and CCD camera. Since single CCD camera with the biprism was used to obtain the stereo image, this system has various advantages over the conventional stereo vision system using two cameras. In this work, principles of the biprism stereo vision system were described, and the relationship between the disparity and depth was derived. The linear calibration method of the biprism stereo system was proposed to calibrate the stereo vision system in more stable and robust ways.
Performance of this sensor system is evaluated through GMAW. Clear molten pool images were obtained using the 880nm laser line filter, and weld pool boundaries on the left and right images were extracted. In order to determine corresponding points in the subpixel order, the intensity-based and filter-based matching algorithms were employed. The results showed that three-dimensional bead geometry including a humped bead could be measured in real time with reasonable accuracy.
