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sathishkumarsathishkumar Unconfirmed Posts: 13 Apprentice

Hi Team,

     we are using UR3e Robot, we have one doubt, can we predict emergency/protective stop ahead before running on the UR3e....? if you see the RoboDK software, we think it has that feature to detect such issues, if we can detect this upfront, we can alert user about it.


sathish kumar R

Best Answer


  • bcastetsbcastets Vacuum Beta tester Posts: 695 Expert
    Maybe I am wrong but I don't think you can.
    If the robot is in a position which trigger emergency/protective stop (robot force on something) before switching the robot ON, you have to change the position manually using back drive mode.
  • sathishkumarsathishkumar Unconfirmed Posts: 13 Apprentice

    Hi Becastets,

         Sorry, your not understand my question, my question is how protective stop is created based on joint limits....?

         if the robot moves based on inverse kinematics means, it is possible to predict the robot before reach the maximum join limit. 

  • David_GouffeDavid_Gouffe Vacuum Beta tester Posts: 56 Handy

    The robot is monitoring the joints and implement a pre-impact "protective stop". Based on internal setting. 

    In the same field, you can add safety planes to cover unsafe areas. Those safety plane can be linked to inputs to activate. 

    The downside of those mechanisms is that it is a safety overwatch. 

    The overwatch is to cover the situation where command is legitimate but the result is not. Ex turning joint 4 but the wrist plane will get in contact with the arm. 

    Maybe there is a parameter in the safety, allowing start earlier and decelerate more slowly. 

    The downside of it is that you cannot predict it easily lives at runtime. 

    The work around is to scope the program and commands to stay in the usable reach and configurations. 
    -Testing the sequence.
    -Limiting the parametric or relative movements. 
    -Using known passage points with tested transition speed to pass from one configuration to another. Using moveJ to force a joint configuration. 
    -Note that if TCP is subject to change, there is a check box to use joint value instead of a position inside moveJ commands. 

    For the direct question:
    " ... how protective stop is created based on joint limits....?"
    It is the joint position value crossing the limits that trigger the protective stop, not reverse kinematics. 
    For the safety plane, it is TCP crossing or, depending on setting, other robots elements crossing the plane. 

    This should help. 


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