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nmellisnmellis Posts: 1 Recruit
Hello all,

I have been working on programming a "new" (purchased in 2017 - just now installing) UR5 in our lab, but have run into an issue of waypoints drifting by a few mm after a force-induced protective stop. My knowledge is still very limited on the matter, but it seems that the zero-point on a joint must have drifted due to the stop, but I've not found any clear information on how to recalibrate things. The program we are running has a lot of waypoints, and it just isn't practical to relearn them individually if something has drifted. 

We have 2 key waypoints at the beginning of the program where the robot touches very specific points to ensure everything is properly aligned. It seems that I would want to recalibrate our UR5 to these key waypoints, which I have attempted to do. However, when I attempt to do this, I am met with a message saying that no new hardware was detected, so it seems that there isn't a way to recalibrate the joints unless you've installed a new joint.

Some help correcting this drift would be greatly appreciated! 



  • matthewd92matthewd92 Founding Pro, Tactile Sensor Beta Testers Posts: 1,261 Handy
    I’ve only seen the robots lose positional accuracy like this when there was something mechanical wrong with a joint, not just because of a protective stop. We have robots with multiple critical waypoints that have been running for years without us needing to adjust the waypoints due to protective stops. 

    I’d check all of your joints and make sure they are all tight and secure. The way the CB3 joint was constructed its possible if the bolts holding the joint are a little loose that the joint could slip on a collision. I know we had an issue with a UR10 similar to this and when we started checking all the joints we found that the bolts at the elbow were totally loose and you could move the joint slightly by hand with some force. We were seeing a similar drifting issue with that robot. Once the joint issue was resolved it ran fine for about 18 months with some very tight requirements at a couple of positions in the cell. 
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