How can I get a URDF file about gello for franka?

[Dai-DY]

I noticed that a gravity compensation feature has appeared in the latest repository, which makes me very excited. I would like to implement the same functionality on the Gello Franka, but I am missing the URDF file. Could you provide it, or share some methods to obtain it?"

[AndreasJosefGassner]

Hi @Dai-DY,

If you’re using the ROS 2 integration, you could try this branch to see if it already meets your needs:
feat/actuation

Based on our tests, full gravity compensation is not possible with the GELLO for FR3, but it does provide some additional support and stability.

[Yewandou7]

Hi @AndreasJosefGassner,

To avoid confusion, I understand that the gravity compensation mentioned here refers to the one described in the FACTR, correct?

I'm not very familiar with these control principles, but it seems their demo can make GELLO hover in mid-air. What does "full gravity compensation is not possible" mean here?

Thank you for your response!

[AndreasJosefGassner]

Hi @Yewandou7, thanks for your response and sorry for keeping you waiting!

You’re right: with FACTR you can achieve full gravity compensation, meaning the arm can hover in mid-air. The key difference compared to the original GELLO setup is the use of stronger motors on joints 2 and 4:
https://github.com/JasonJZLiu/FACTR_Hardware?tab=readme-ov-file#step-2-update-servo-ids

Based on our tests, we don’t expect this to work reliably with the standard motors used in GELLO. That said, we’re absolutely open to contributions — if you manage to get it working, we’d be more than happy to review a PR!