7th joint of IIWA7 cannot be mastered back to within its joint limits

    I have a problem with the 7th joint of the IIWA7. The joint was shaking when running a program so I stopped the robot. After that, I could see that the 7th joint of the robot was way out of its joint limits on the monitor, even though the joint never moved to that position. I think that there is an error that somehow has added an offset of around -360 degrees to the 7th joint.

    Currently it is at -235 degree, but when I try and move it back within its joint limits its stops at -189 degree. I can move it all the way to -531 degree, but then it stops again. When I try to master the joint, the error "Axis 7 was not mastered successfully, unknown reason" Shows up.

    I have tried:

    * Several reboots

    * Unmastering all the joints

    but to no avail.

    Has anyone faced similar problems?

    Edited once, last by lasaiiw (August 20, 2020 at 3:37 PM).

    • Best Answer

    I've never seen anything like this, but my best guess is that you have an actual mechanical or electrical issue in the joint -- my money would be on the resolver in the servo motor coming free from the drive shaft. And the iiWA is not user-repairable -- if I'm right, I suspect your only recourse is going to be to get it repaired by KUKA.

    Problem solved after contacting Kuka support. The solution is the same as in this thread.

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