Optimal Transitional Trajectory Planning For Arc Welding Robot

As the development of industrial automation, industrial robot has been a hotspot for research and application in recent years, and trajectory generation is a basic task for robot and other computer numerical control machine. The continuity for trajectory leads to robot efficient and energy consumption.Most of trajectories consist of line segments and transitional segments. Line segment is a straight line, circular or oval shape, and the transitional segments are switching tracks between different line segments. The more smoothness and continuity the trajectory is, the higher efficient, lower energy consumption the robot will be.To ensure the smoothness of the trajectories, a high order polynomial is used to generate line segments or transitional segments. For some robot applications (e.g. arc welding robots), the movement speed is required to be constant. The circular curve is for the transitional segments. The trajectory composed by linear line and circular curve is able to ensure the continuity of position and velocity. But there are discontinuities for acceleration. To reduce the discontinuities, the transitional arc needs to have a bigger radius. But bigger radius will result in bigger trajectory error. To balance these two objectives, a genetic algorithm is adopter in this paper to generate an optimal trajectory with constant velocity. The proposed method is able to keep the transitional acceleration and error as small as possible.