Assemble URDF models

Omniverse Isaac Sim
1

Hello,

My goal is to assemble two URDF models to create a mobile manipulator (for now I try with URDF examples carte and ur10).

It seems that AssembledRobot is the way to go (Assemble Robots And Rigid Bodies — Isaac Sim Documentation).

To import it I need omni.isaac.robot_assembler extention that I have enable using this tutorial: Python Environment — Isaac Sim Documentation.

But when I run my code on Ubuntu 22.04 using ./python.sh, isaacsim 4.5.0, I have an error:

[16.046s] [ext: omni.isaac.robot_assembler-2.0.2] startup
2025-06-04 06:37:22 [20,467ms] [Error] [omni.kit.app._impl] [py stderr]: Traceback (most recent call last):
2025-06-04 06:37:22 [20,467ms] [Error] [omni.kit.app._impl] [py stderr]:   File "/home/rporee/isaacsim/../phd/isaacsim_test/urdf_carter_ur10.py", line 10, in <module>
2025-06-04 06:37:22 [20,467ms] [Error] [omni.kit.app._impl] [py stderr]:     from omni.isaac.robot_assembler import AssembledRobot
2025-06-04 06:37:22 [20,467ms] [Error] [omni.kit.app._impl] [py stderr]: ModuleNotFoundError: No module named 'omni.isaac.robot_assembler'

Even if the extension as startup, it is not found by the code.

Here is a reproducing example:

from isaacsim import SimulationApp

simulation_app = SimulationApp({"renderer": "RaytracedLighting", "headless": False})
from isaacsim.core.utils.extensions import enable_extension

# Enable required extensions first
enable_extension("omni.isaac.robot_assembler")
simulation_app.update()
from omni.isaac.robot_assembler import AssembledRobot


simulation_app.close()

I have search but find no answers.
If you have any clue, please help.

2

@remi.tortue i am just another user, and this is a long shot - have you tried using the extension issacsim.robot_setup.assembler as opposed to omni.isaac.robot_assembler and see if anything changes on your end?

if not, could you elaborate on how you installed Isaac Sim? was it through pip or is it a workstation installation?