[Isaac Sim 6.0.0] USD to URDF export produces empty robot name attribute, breaks re-import

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6.0.0
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Operating System

Ubuntu 24.04
Ubuntu 22.04
Ubuntu 20.04
Windows 11
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GPU Information

  • Model: NVIDIA RTX 5070 Laptop GPU
  • Driver Version: 591.74

Topic Description

[Isaac Sim 6.0.0] USD to URDF export produces empty robot name attribute, breaks re-import

Detailed Description

When exporting a robot USD to URDF using File > Export to URDF in Isaac Sim 6.0.0, the generated URDF file has an empty robot name attribute (<robot name="">). This makes the exported URDF invalid, because re-importing it into Isaac Sim fails with a parsing error stating the robot name is required.

I was trying to export Isaac Sim’s built-in robot USD assets (e.g. UR3, UR10e) to URDF in order to compare with other similar urdfs. I expected the exported URDF to contain a valid robot name, as it does in Isaac Sim 5.1.0. Instead, the name field is exported empty, and the file cannot be re-imported without manual editing.

The same export workflow in Isaac Sim 5.1.0 correctly populates the robot name (e.g. <robot name="ur3_usd">) and the resulting URDF imports without any issue.

Steps to Reproduce

  1. Open Isaac Sim 6.0.0
  2. Add a robot from the content browser to the stage (e.g. UR3 from Isaac/Robots/UniversalRobots)
  3. Delete the fixed root_link,root_joint (and ee_joint if present) so the export proceeds
  4. Go to File > Export to URDF, set the root prim path, and export
  5. Open the exported .urdf in a text editor — the <robot name=""> attribute is empty
  6. Attempt to re-import the same URDF via File > Import — import fails

Error Messages

Failed to convert assets ['C:/dev/USD_to_URDF/ur3_isaac6.urdf'] since importer failed with Error parsing XML: robot: name is required (line: 2).

Additional Information

  • Isaac Sim version: 6.0.0.0 (Full)
  • OS: Windows 11
  • GPU: NVIDIA RTX 5070 Laptop GPU

What I’ve Tried

Manually editing the exported URDF to add a robot name (changing <robot name=""> to <robot name="ur3">) resolves the issue — the URDF then imports successfully. This confirms the only problem is the missing name attribute at export time. The same robot exported from Isaac Sim 5.1.0 includes a valid name automatically.

Additional Context

This appears to be a regression in the 6.0.0 USD-to-URDF exporter compared to 5.1.0 only the robot name attribute is affected.

2

Closing. Let’s follow up this issue through [Isaac Sim 6.0.0] USD to URDF export produces empty robot name attribute, breaks re-import · Issue #668 · isaac-sim/IsaacSim · GitHub.