I would like to follow the outline of a circular metal piece which has a large diameter (2m) to perform a deburring operation, applying a very light but constant force at the point of contact.
For this, I put the piece on a turntable next to the IIWA, and I asked the robot to remain static (positionhold). Then I changed different impedance control parameters (stiffness, additional strength, damping, etc ...).
The problem I encounter is that my part is not perfectly centered on my turntable, or has slight defects (<1mm), so sometimes the TCP is in contact with the part, and sometimes it is not.
I hoped that the sensitivity and flexibility of the robot would compensate for this, while always applying the same effort on the part. But even changing the different parameters I mentioned earlier, I cannot get constant pressure on the part: the IIWA will not press enough in some places, and will press too much in other places.
What would be the best approach to achieve what I am trying to do?
Because for now I use a "positionhold», but the results are inconclusive. In addition, is there a way to achieve a "positionhold" having as origin a point that the robot has not yet reached? Because I thought to put the origin of the "positionhold" (and thus the virtual spring) inside the part rather than on a point of contact, so that the spring force is directed inwards of the part and not outward as is currently the case.
Thank you in advance for your help