Novel Real-Time Seam Tracking Algorithm Based on Vector Angle and Least Square Method

Real-time seam tracking can improve welding quality and enhance welding efficiency during the welding process in automobile manufacturing. However, the teaching-playing welding process, an off-line seam tracking method, is still dominant in automobile industry, which is less flexible when welding objects or situation change. A novel real-time algorithm consisting of seam detection and generation is proposed to track seam. Using captured 3D points, space vectors were created between two adjacent points along each laser line and then a vector angle based algorithm was developed to detect target points on the seam. Least square method was used to fit target points to a welding trajectory for seam tracking. Furthermore, the real-time seam tracking process was simulated in MATLAB/Simulink. The trend of joint angles vs. time was logged and a comparison between the off-line and the proposed seam tracking algorithm was conducted. Results show that the proposed real-time seam tracking algorithm can work in a real-time scenario and have high accuracy in welding point positioning. © 2017 Editorial Department of Journal of Beijing Institute of Technology.