URDF Export Error and Collision Object Error with Left-Handed Rotation Matrix

[1270645409]

Describe the bug
I have created mutiple .obj files in blender, then composite them to a urdf
I encountered two issues when exporting Blender models to URDF using Phobos.

PLEASE NOTE THAT No transformation has been applied to the origin .obj mesh

Issue 1: Rotation Matrix Error

Error Message:
'''
Rot.from_matrix(R).as euler(EULER CONVENTION)
Non-positive determinant (left-handed or null coordinate frame) in rotation matrix
'''
Also, I meet this error when creating collision object

Context:

This occurs when exporting a URDF containing multiple objects assembled as links.
Temporary Fix: Flipping/mirroring the problematic object sometimes resolves the error, but this approach is unreliable.

Issue 2: Collision Object Pose Mismatch

Problem:

When creating a collision object (mesh), its pose differs from the original visual object. Specifically, the collision mesh requires an additional 90-degree rotation around the X-axis to align with the visual geometry.
Sometimes, the same problem occurs as the issue 1.

I don't know whether it is normal

To Reproduce
Steps to reproduce the behavior:

1. import two obj(body and lid)
2. set them to visual
3. create link for them
4. set the body link to root
5. set "bone relative" for the two link
6. select one visual obj, create collision for it, then error occurs
7. also, when i try to export the whole urdf, the same error occurs

Expected behavior
for issue 1, I want to export urdf successfully
I want to know why the rotation matrix is left-handed

for issue 2, I want to know why the created collision obj pose is not the same as visual one.

Screenshots

Desktop (please complete the following information):

• OS: Ubuntu 22.04
• Blender version 3.3LTS

Additional context
scipy==1.13.1
phobos=2.0.0

E.g. URDF version, mesh type/version etc