Control strategies for very low speed trajectories of an industrial robot

The paper discusses a few theoretical, numerical and practical aspects involved with the motion of an industrial robot over trajectories at very low speed, which is a common duty mainly for employment in arc welding. In the first part some details on the technological implementation of the arc welding and dedicated trajectories are reported, with special reference to the weaving motion. A custom-made algorithm able to overcome a few significant problems is then proposed. The algorithm is finally tested on a 6-axes industrial robot and a number of relevant results are shown for trajectories ranging in the field 5-15 mm/s, including a test based on an adaptive procedure and a comparison with standard industrial controller. A final discussion on the results completes the presentation.