I am trying to export a humanoid robot USD file included in the assets
(GR1T2_fourier_hand_6dof_physics.usd) to URDF.
I added the extension for exporting to URDF and performed the export, and a URDF file is successfully generated. However, when I import that URDF again, the links that originally existed in the Stage Tree are missing.
Is there something wrong with the way I am doing this?
I would appreciate any advice.
Steps to Reproduce
Add GR1T2_fourier_hand_6dof_physics.usd using Add Current Selection
Generate a URDF file using Export to URDF
Import the URDF file created in step 2
Screenshots or Videos
The attached image shows the exported URDF being re-imported.
Why are you trying to get USD into URDF? Normally in the vast majority it is the other way around. You build your robot in CAD software, you export either to usd or urdf, and then if urdf, you can import that into Isaac Sim and save as usd. Once it is in Isaac Sim as usd, why are you then trying to go back to standard urdf?
To provide some background, I am currently attempting to generate motions for a humanoid robot by referring to the motion-generation website mentioned below. According to the information provided on the site, a URDF file is required for this process.
As I did not have an original humanoid robot model available, I decided to conduct my experiments using an existing Isaac Sim asset (GR1T2). While I was able to locate the corresponding USD file, I could not find a URDF file. For this reason, I am currently attempting to export a URDF file from the USD file.
If there are any misunderstandings or incorrect assumptions in my current understanding of the motion-generation methodology, I would greatly appreciate it if you could kindly point them out.
Thank you very much for your time and consideration.
There is no easy way to go from USD “back” to URDF. It is all designed the other way around. URDF is generated directly from solid modeling CAD software. You need to remake the robot asset then, or buy an asset with a URDF or a solid model of the robot in STP etc.
Closing this thread — the core question has been addressed: the USD-to-URDF exporter does not produce a fully round-trippable URDF. For RMPflow / Lula configuration, a robot description file (URDF or YAML) authored from the original CAD source is recommended. If you have the GR1T2 URDF from Fourier’s official repo, that would be the correct input. If you still need help, feel free to open a new topic.
