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SebastienSebastien Posts: 219 Handy
Hi pros,
one quick question, I saw a video showing the repeatability of the UR robot:


Listed in the specifications of the UR robot is a repeatability of 0.1mm. A question that we have been asked is that the video above shows that the robot is within the specs given. What if you turn off and then on the robot and try to run the same program. Would you still be within the limits or will the robot initialisation steps make this deviate a bit more?

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  • matthewd92matthewd92 Posts: 927Founding Pro, Tactile Sensor Beta Testers Handy
    I would presume that it should have the same repeatability with the absolute encoders.  That would be an interesting test to run, to e-stop the robot, start it back and see if it holds the same, or to have someone interfere with the robot and see what the numbers look like after resuming operation.

    @Ryan_Weaver any interest in doing that from the Axis folks?  
  • Ryan_WeaverRyan_Weaver Posts: 46Founding Pro, Partner, Beta Tester VIsion 1.1 Program, Wrist Camera URCap 1.3.0 Handy
    I'm with @matthewd92 , I think that the absolute encoders are what dictate the repeatability and there is nothing that changes mechanically after you e-stop.  The robot still knows where it is.  

    I think that is proven by many customers running tasks with tight tolerance who turn off their machine every night, yet the robot hits the points it needs to when they power it up in the morning.  


    Ryan Weaver   |   Automation Engineer   |   Axis New England
    [email protected]
    https://www.youtube.com/user/AxisNewEngland
    https://twitter.com/axis_newengland

  • Etienne_SamsonEtienne_Samson Posts: 416Beta Tester Beetle, Wrist Camera URCap 1.3.0, Vacuum Beta tester Handy
    Hi guys, the only time I have seen the repeatability drift is with a joint change.

    I guess @Stefan_Stubgaard could explain us why repeatability doesn't drift with reboot or joint firmware update. Stefan?
    Etienne Samson
    Technical Support Director
    +1 418-380-2788 ext. 207
    [email protected]
  • Grady_TurnerGrady_Turner Posts: 67Founding Pro, Partner, Beta Tester VIsion 1.1 Program, Wrist Camera URCap 1.3.0 Handy
    @Ryan_Weaver @matthewd92 @Stefan_Stubgaard

    The only time we have seen a loss of repeatability was when the robot crashed at full speed into the machine structure.  The base joint mechanically shifted in it's locking key mount, we had to re calibrate to get the program positions back 
  • matthewd92matthewd92 Posts: 927Founding Pro, Tactile Sensor Beta Testers Handy
    @Grady_Turner don't you know you're not supposed to do that?
  • Grady_TurnerGrady_Turner Posts: 67Founding Pro, Partner, Beta Tester VIsion 1.1 Program, Wrist Camera URCap 1.3.0 Handy
    @matthewd92  It wasn't me driving when it happened! :smile:
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