Curious About All Aspects of Your Work

[brunoleej]

First of all, thank you so much for providing all the materials related to your incredible project and paper.

This project has become a great source of inspiration for my future research.

I have a question regarding the terrain assets and the robot used in your simulation.

Could you share how you created or obtained these elements? In my case, I have a robot similar to a variation of F1Tenth (called Xycar), but since there is no available URDF for it, I find it difficult to import it into simulation environments.

Specifically, I’m curious whether the USD files and URDFs for the MuSHR robot and its simulation environment were modeled by you directly, or if there is a platform or source that provides these kinds of resources.

Once again, thank you for the amazing project and impressive research work.

[geiko246]

Hello! Thank you for your kind words and the question!

Specifically, I’m curious whether the USD files and URDFs for the MuSHR robot and its simulation environment were modeled by you directly, or if there is a platform or source that provides these kinds of resources.

The MuSHR USD is a conversion of the URDF from the original source: https://github.com/prl-mushr/mushr#component-documentation. But, we found these articulations to be too inaccurate for our Sim2Real tasks. For example, the steering joint was right in the middle of the wheel.

I had to upload this URDF to Isaac Sim and rig the robot to improve steering linkages and to model the suspension. Interestingly, the suspension is actually just another prismatic joint with a p-gain😆.

If you're okay with not rendering the meshes right away to test the physics, I'd recommend just starting out with the MIT Racecar URDF which is what we did. It's just a rectangular mesh with four rotating wheels and two steering. But, you can easily see where to change the car parameters (wheelbase, length, height, etc.) for your early development.

If you need suspension, you can also re-rig the existing mushr_nano_v2.usd to match your car parameters or try and move these prims over to your model in Isaac Sim. I would not recommend this though unless you're very sure you want it because rigging was quite annoying to do.

[geiko246]

If you end up using the Racecar URDF, please consider contributing it and its configs! I imagine you aren't the only one who might find that early-stage asset useful.

[brunoleej]

Thank you for your kind response! I’ve only recently started conducting research on mobile robot racing.

My main research interest at the moment is how to effectively transfer training from simulation to the real world.

I look forward to producing even more exciting research through this project.

[geiko246]

Oh, and the terrain assets were CADed outside of Isaac Sim and then converted to a USD but this is definitely not the way to do this well in Isaac Lab since there's lots of auto-generation infrastructure: https://isaac-sim.github.io/IsaacLab/main/source/api/lab/isaaclab.terrains.html

For some reason, I remember we couldn't get these working at the time.