Tool drifting / not moving square in Base frame

Technical Questions
1

Hi,

I’m having an odd problem while manually moving the UR5. I place the robot tool flange into a certain position. Then I use a level to make sur the tool is pointing straight down. then I move the tool flange only with move tool X, Y or Z (so only translations) to a desired location, but the tool has also rotated about 2 degrees over the tool Y axis and about 1 degree about the tool X axis. So I need my level again to straighten the tool orientation, but then I have to move again, which leads to the tool being mis aligned again, etc… I checked, but the TCP is all set to 0, so no offsets or rotations in the installation. Why doesn’t the flange keep the orientation when performing only tool translations? What am I missing here? It’s an older model, circa 2012 / 2013, so still relative encoder positions, not absolute.

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2

Did you have set the corresponded Frame to Base in the Move-Tab?
If it is still set to View, could explain the deviation in the orientation.

3

Hi,

Yes, I’ve made sure I used tool view, not “View” (remember it’s an older CB!). I’ve checked again this morning to be sure, but it’s really there. I reconfirmed that I set all TCP’s to 0 both move and for view. If I set the tool flange parallel to the base (by setting joints at 90 degrees), I already have the same error in tool flange alignment. Could this be a robot calibration problem? What can I do to verify / adjust?

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4

I would indeed recommend re-calibrating the robot and then checking the problem persists.

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