Universal Robots Forum

Making force pull up

I got some parts which stick together with oil. To get them to separate I need to pull on them for a bit, which will then cause the oil to slowly release.

However, I can only get the robot to push down. I have tried to put the robot into force mode, use the base as reference to it, and the robot correctly moves up and down when using the test function. But when I run the program the robot only presses down. I have tried to put both a positive and negative value into the field, but it still presses down only.

Is there something else I need to do to get it to pull up instead of pushing down?

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Not sure what you’re using, but I use it on about half my programs to push parts down, but should work the same up. I just tested on my UR10e.

Add a force node, set to basic, using base. Start by using a small-ish value like 2 or 4. Move the arm to a safe position, press TEST, hold the Freedrive button momentarily without holding the arm. The arm should drift up. If not, try bigger values.

Change the value to -2 or -4, press TEST, hold the Freedrive button. the arm should drift down.

Of course, it’s probably a good idea to make sure your payload and COG are fairly accurate. Without being in a Force node, press the Freedrive button and let go of the arm. See if the robot drifts up or down. If it does your payload / COG are not set correctly.

Hope this helps.

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Sorry for the late reply, something came up and I didn’t have time to do more testing.

I don’t have an E model, I tried to do as you said, but it still only goes down. In the task it is doing multiple things by using force() to detect where the parts are and such, and it a bit of a mess and also a bit unreliable there as it is out at almost full reach of the arm. I have ordered some sensors to help detect the parts instead, so hopefully I an now more reliably detect the parts, and focus more on how to get them pulled apart.

Sorry, didn’t know if you were using an e model or not.

Did you play around with the weight values? Bigger, smaller, +, - etc?

Let us know what robot you’re using and more info on your setup and process, etc and we might be able to come up with a good work-around if force mode on your model does not support force in multiple or various directions.

How much force are you applying? I would recommend at least 15 N maybe a little more. Also make sure you are either in simple force mode or frame force mode.