How do you verify the robot's positional repeatability or the robot's accuracy?

Tyler_Berryman 2016-08-22

Other than using the robot's encoder data or using a probe with an indicator? Do you guys have any tricks?
@Ryan_Weaver @olivertan @Kaleb_Rodes

Grady_Turner 2016-08-12

@Tyler_Berryman I can't think of a way to do so without using some sort of sensor except by eyeball (not so effective). We've had customers use a micrometer in a test program. The program had several waypoints all at full speed and high acceleration, and also with a full payload. Every cycle one waypoint was used to touch off on the micrometer and it was found that the robot was withing +/- 0.002 inches ( < 0.1 mm).

Kind of went against the question, but hope this might help!

Tyler_Berryman 2016-08-12

@Grady_Turner Thanks for the answer. I think this is probably the safest way to verify the robot's precision and the easiest way to get a quantitative measurement.

I found a video showing the verification of the precision of a UR.

https://www.youtube.com/watch?v=9orN_aUDY7w&feature=youtu.be

Ryan_Weaver 2016-08-12

@Tyler_Berryman - thanks for finding the video, saved me the time ;)

I wished that indicator had more decimal places of precision, because it really needs to be better than 100um resolution to tell much about the UR's repeatability. But it was the best I had available.

The other thing to keep in mind is that video is only measuring repeatability in one dimension, so we would expect it to read better than 100um on average.