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SebastienSebastien Posts: 219 Handy
Hi pros,
we are working on a safety analysis for a UR10 application with Robotiq gripper. I have two questions.
1-How do you treat the fact that the operator can have his hand stuck in the 2F85 gripper which has a closing force of 235N and the quasi-static limit for fingers is 140N in the TS15066.

2-Are you simply doing like I do to calculate the effective mass of the robot in order to calculate the maximum speed that the robot can go at? I simply use the TS15066 formula where EffectiveMass = (Mass of robot moving part/2) + Effective Mass of robot payload.
In that formula I simple assume mass of moving par of the robot to be the weight of the robot and the effective mass of the payload to be tooling weight plus workpiece weight.
What are you pros doing?



  • ColinColin Partner Posts: 17 Apprentice
    I believe I can help with the first part. 

    1 - The 2F-85 gripper has a chart in its installation manual that shows the semi-linear relationship between closing speed and force. You can always set a maximum allowed closing speed in a UR thread or have a monitoring variable in an event that looks at the closing speed and triggers a robot halt upon exceeding that allowable speed. If you select the proper maximum speed and closing force values and set monitors to each, that is one way to limit the force exerted on fingers. The obvious better solution is to prevent any human body part from getting that close to the robot, but if that is unavoidable then maybe try the first part of this post. 

    2 - Sorry I can't be of help on the latter point. 

    Good luck!
  • BMatthiasBMatthias Posts: 2 Recruit
    Dear Sebastien, 
    I've noted that your post is from over a year and a half ago.  Nevertheless, let me suggest a possible reference to address your second question:
    See in particular section 4.2 in which Khatib develops the expression for the effective mass at the point of contact / point to which the Jacobian transformation applies.  
    The formula given in ISO/TS 15066 is an extreme simplification, which hopefully does alright in most practical cases. 
    Best wishes.
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