April 25, 2019, 02:10:13 AM
Robotforum | Industrial Robots Community

 Protective force

Author Topic:  Protective force  (Read 256 times)

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March 26, 2019, 01:06:25 PM
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johmarjac


Hello,

I have a UR3 Robot here and I have a question depending the protective features.
In the Installation -> Security tab I can configure the maximum force the robot can bring up. Unfortunately the least value I can set this to is 50 Newton. Does this mean the robot cannot go into protective stop under this value? The thing is, I need to drive a grabber + grabbed tool to a grinder and I want the robot to go into protective stop if the grabber + tool drives into the grinder. Lets say if it has a resistance more than 100 grams, it should go into protective stop to not damage the grinder or the tool. How can I achieve that? It cant be true that the minimum resistance is ~ 5 KG.

Thanks in advance.

Today at 02:10:13 AM
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April 01, 2019, 11:41:57 AM
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matthewd92


Are you using a CB3 or an e-series robot?  On both you can use built in force monitoring to get out of the situation,

MotionComplete=False
If force()<30
  Do some motion
  MotionComplete = True
Else
  Back away
  Pop-up some message

Set the checkbox on the if statement to be monitor continuously and that way it will break out of the if statement and would enter the else portion of the command. You can make this work on a CB3 but it’s tricky as there is no FT sensor. As there is one on the e-series you will get actual force readings. The other alternative is to install an FT sensor from someone like ATI, Robotiq or OnRobot/Optoforce.


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April 10, 2019, 11:51:15 AM
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johmarjac


I am using a CB3.

The force() checking should then be executed in a separate thread right? Because it is not possible to check the force while the robot moves from waypoint to waypoint. Then when checking the force in the thread and the force exceeds an X amount then I could force the robot to stop?!

April 10, 2019, 12:12:04 PM
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matthewd92


If you check the box on the if statement to check continuously Polyscope takes care of handling the thread for you. Turns the statement into a while loop instead of just an if statement.

You can also run it in a thread if you want. We often do that so we can take the tcp force list and assign to variables that we can use.


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