Three Dimension Curve Welding Seam Modeling for Seam Tracking

A novel modeling method for 3D curve welding seam is presented in this paper based on a welding robot for large workpiece. The 3D curve welding seam tracking is implemented by macro and micro motion which can control translational motion of torch in a large range and implement accurate seam tracking in small range. As such, the self-teaching seam model and real-time seam model are established to accurately control position and orientation of torch. The self-teaching model is obtained by a cubic B-spline interpolation function. Then a continuous position model of a V-type seam is established by using the cubic parameter B-spline least square method. The orientation model of the seam is also established by using the position model and coordinates of seam characteristic points. These three models form the base of macro and micro translational motion control and real-time tracking control. Furthermore, in order to compare the performances of the different position modeling method, simulations have been carried out to produce the modeling results of cubic parameter B-spline least square method and polynomial least square method. The effectiveness of these seam model has been verified.