Can Force be used in Palletizing Operation?

We are using a UR10e with a vacuum fixture mounted on the tool end. We are “picking” parts from a grid of stacked parts. The parts are thermoformed, therefor there are slight variations in the thickness of the stacks. It would be optimal if we could apply a force event to the MoveL to the ToolActionPoint in the De-Palletizing template, so that we could control the pressure and ensure a good seal for the vacuum fixture before turning on the vacuum. Is something like this possible during a de-palletizing operation?

Thanks for any insight here!
Bruce

Yes, I use Direction nodes in pallet operations all the time to slide parts against stops so I can pick them up in the right orientation and don’t have to worry about humans putting the parts in “just the right place”.

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My palletizing nodes are locked…how do you get access to add a force function, for example?

Are you using the teach pendant or…?

Here’s what my pallet nodes look like. I can put anything I want into the At Each Item node.

In this case I use Direction Base: Z- to touch the table. I think you can probably do something similar. If you post part of your code would make it easier.

Here’s what a Force function could look like:

Thank you! I was trying to add the Force event in the wrong location!

Thank you for your help last week! In the above example, you have Direction: Base Z-, and then Force Until contact: operation. Where is this located in Polyscope? I can add a Force Template, then Find Surface under URCaps, which seems to work ok…but not sure how to set a Direction, Until contact move…

Thanks! Sorry for my noobi questions!

It’s under Basic > Direction

It adds a moveL() function with direction function nested in it, you just have to define the UNTIL to Tool Contact

What @michael.r.mercer said. The “Force” that we use in “Direction” nodes is completely different than a “Force” node. Uses the same hardware but packages it so it’s easier to use.

Also, you can stack multiple "Until"s (Expression, Distance, Contact and I/O input).

I use them a lot to test if parts are in the right position.

In this case I use Until Contact with a “Popup” action and then Until Distance with no action.

With the Contact node first the robot will verify by NOT hitting something that’s not supposed to be there. (If it hits something it’s not loaded correctly.)

By using the Distance node first the robot will verify by HITTING something that’s supposed to be there.

image

Hope this helps.

Man, I couldn’t see the forest for the trees! Thanks guys!

Is there any way to set the Newtons force when using the “Until Contact”?

Not with “Tool Contact” but you can use the “Expression” field and say “Force() > YOUR_NEWTONS.” Just be sure to put the “zero_ftsensor()” script command before doing this, otherwise you’ll see a lot of false positives.

I threw in a simple debugging thread, which can be used to monitor the actual force reading in the “variables page” if you wanted to watch that value for verification. You should see it drop to 0 when the “zero_ftsensor()” line is executed, and in this case, jump all the way up to 50 when running the “until” portion.

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Yes that makes sense. I have mounted a vacuum fixture on the robot and am picking up stacked parts in a grid. I think I may need to adjust the force so that it seats correctly. Thanks!