OpenArm's Robot Description File (URDF) in Isaac Sim

[aascropv]

Describe the problem you got

I have tried the tutorial:OpenArm Description Package to generate the URDF.

But, when I imported it into the Isaac Sim and used the Lula Robot Description Editor to generate the robot configuration like the Isaac Sim tutorial here:Tutorial 8: Generate Robot Configuration File , it caused the error.
2026-03-13T07:38:04Z [81,701ms] [Error] [omni.ui.python] ValueError: Non-positive determinant (left-handed or null coordinate frame) in rotation matrix 0: [[ 1. 0. 0.] [ 0. -1. 0.] [ 0. 0. 1.]]. At: _rotation.pyx(1136): scipy.spatial.transform._rotation.Rotation.from_matrix

I have searched online and found that the URDF I generate have some problems. The main issue is the scaling : I found that the meshes of all components scale down 1000 times and the y axis of some component are -0.001 (negative).

This will cause error because the physics engine of Isaac Sim can't convert it. Before I have used the Unitree Z1 robot arm, its URDF's scale is "1 1 1". But I am not sure how to solve this problem correctly.
Has anyone run into this issues when using Isaac Sim Lula Robot Description Editor to make the collision sphere and generate the robot configuration?

[abetomo]

Notes from looking into this:

The negative -0.001 comes from how the left arm is generated by mirroring the right arm:

openarm_description/urdf/arm/openarm_macro.xacro

Line 31 in e1e52ce

<mesh filename="package://${description_pkg}/meshes/arm/${arm_type}/visual/${name}.dae" scale="0.001 ${0.001*reflect} 0.001" />

openarm_description/urdf/arm/openarm_macro.xacro

Line 37 in e1e52ce

<mesh filename="package://openarm_description/meshes/arm/${arm_type}/collision/${name}_symp.stl" scale="0.001 ${0.001*reflect} 0.001" />

For the left arm, reflect = -1, so the scale becomes 0.001 -0.001 0.001.