Missed rclpy module in IsaacSim 2022.2.0 on Windows11

Hello all,

We are heavily using IsaacSim(with ROS2) on the Linux machines and now we would like to use OV VR, and it requires Windows.

I’ve installed IsaacSim and I can run the application without any issues.
But we would like to use python to run our applications and we faced the issue that rclpy can not be found. Here is the log when we are trying to run standalone example by command
python.bat standalone_examples\api\omni.isaac.ros2_bridge\subscriber.py

[6.574s] Simulation App Starting
[14.266s] app ready
[14.536s] RTX ready
[14.888s] Simulation App Startup Complete
[14.910s] [ext: omni.isaac.ros2_bridge-1.10.1] startup
Traceback (most recent call last):
  File "C:\Users\yuriy\AppData\Local\ov\pkg\isaac_sim-2022.2.0\standalone_examples\api\omni.isaac.ros2_bridge\subscriber.py", line 26, in <module>
    import rclpy
ModuleNotFoundError: No module named 'rclpy'
Exception ignored in: <function _make_registry.<locals>._Registry.__del__ at 0x0000018C4C350CA8>
Traceback (most recent call last):

According to the comments, rclpy should be precompiled, but I’m not able to find it in the IsaacSim files

# Note that this is not the system level rclpy, but one compiled for omniverse
import rclpy

What we are doing wrong?

1 Like

Hi @yfedi

I can’t answer the question but I can offer a possible solution: compile ROS2 for Windows with Python 3.7 to use the rclpy package

The version of the NVIDIA Omniverse Python environment is 3.7. It is not possible to use the binary files of the available ROS 2 distributions (Foxy e.g.) because they are compiled with Python >= 3.8. Then, it is necessary to compile the ROS2 source using Python3.7

Despite how tedious the steps may seem, I managed to compile the distribution without major problems (on Windows 10) and use the rclpy package

Follow the instructions in Windows (source) taking into account the following:

  • Install Python 3.7.9 instead of the version indicated in the steps and make sure that this or any other Python 3.7 environment is the only one available in the command prompt

    choco install -y python --version 3.7.9
  • Use the following command to identify errors in case of compilation failure

    colcon build --merge-install --packages-select PACKAGE_NAME --event-handlers console_cohesion+

For using the compiled distribution with Isaac Sim, I had to replace the .dll files in the <path_to_isaac_sim>\exts\omni.isaac.ros2_bridge\bin folder with the compiled ones in install\bin folder. After that, and unlike Linux (according to the documentation in Isaac Sim), source the built ROS2 distribution before running Isaac Sim

Please, let me know if all goes well if you decide to follow this path :)


I thought about this solution, but I don’t like the idea to change binaries in the installed package.
But, I will try …

Yeah, I know that modifying the dll files in Isaac Sim’s omni.isaac.ros2_bridge extension (bin folder) is a questionable solution… but that’s what I found to make it work…

Btw, only replace the 26 common dlls. There are 3 others belonging to Isaac Sim

Make a copy of the extension just in case :)

Finally, I’ve managed to make it work. And I didn’t need to replace dlls in the IsaacSim installation folder.

Here are steps to fix this(just to make it more clear):

  • Install Python 3.7.9 instead of the version indicated in the steps and make sure that this or any other Python 3.7 environment is the only one available in the command prompt

  • Install ROS2 foxy from the sources https://docs.ros.org/en/foxy/Installation/Alternatives/Windows-Development-Setup.html

  • In case of ROS2 build failures(most probably it will happen), check what packages(like numpy) are missed and install them separately

  • Source the built ROS2 distribution (call \local_setup.bat)

  • Run your IsaacSim script

Thank you


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