Research On Motion Simulation Platform For 6-DOF Welding Robot

Currently the welding robots are still mainly applied and employed in manual teaching ways, which has low efficiency, poor security, and is vulnerable to human factors and so on. Therefore, the thesis studied the determination method of the welding trajectory and the attitude of the welding torch, focusing on the intersection seams which are prevalent in actual production practice but difficult to achieve automatic welding, and developed a motion simulation platform for 6-DOF welding robot, so as to improve the efficiency of automatic welding.First, for the spatial complex intersection seams between workpieces or structural components in basic geometric shapes which are quite common in practice, the thesis proposed an adaptive searching method to get the coordinates of the welding trajectory points for the two intersecting workpieces in different shape combination, geometric dimension, spatial position and attitude. In the method the density, even degree and searching precision of the trajectory points are customizable.With the welding trajectory points obtained, the attitude of welding torch at each point is computed according to the surface information of the intersecting workpieces.The homogeneous transformation matrix from the front end coordinate system of the welding torch to the global coordinate system is calculated with the coordinates of the welding trajectory and the attitude of welding torch. On the basis of the D-H model which is established according to the structural characteristics of the 6-DOF welding robot, the joint angles of the 6 axes at each trajectory point are computed by inverse kinematics equation. The forward kinematics model is also analyzed for the computation of the position and attitude of the welding torch in virtual teaching.Based on the research above, the motion simulation platform is developed. The 3D modeling and editing of workpieces, the graphic simulation of welding process, virtual teaching and some other functions are realized in the platform.Finally, the thesis conducted several experiments on the searching method and the simulation platform, which validated their feasibility.