Universal Robots Forum

Using the CoBot as a measuring device to measure straightness

I’m currently using our CoBot to measure surface heights. To do so, I lower the Cobot onto the surface until a defined force is reached. I then save the height of the TCP.

At the moment, I am not able to distinguish differences in the region of 0.05 mm by that method.

To clarify, I’m using the force copilot URCap. I give a downward force of 5 N onto the Z axxis, and let the tcp drive a prerecorded path (in which it is standing still, with no force applied). I save the height at the moment it doesn’t change anymore in a seperate thread.

Have I reached the limit of what is possible with the CoBot, or are there other methods to measure objects in a touching manner?

0.05 mm (.002 inches) is well past the robot’s capabilities.

I believe 0.10mm is the best you can get and that would be under ideal conditions. If you’re getting 0.05 you’re doing well.

E-series robots have a pose repeatability of 0.03mm for the 3e/5e and 0.05mm for the 10e/16e. With that said, any sort of error in the rest of the system will probably take you out of the range that you are looking for.

Has this changed in the last 2 years? I’m fairly positive we were told 0.1 when we bought ours.

Nope, E-series has always had those numbers. CB3 does have 0.1mm for repeatability though.

Oh. I sit corrected (and deceived?) <—Totally not complaining! :stuck_out_tongue_closed_eyes: