moonbot_builder

Build Moonbot robot assemblies, URDF descriptions, and level-1 runtime parameters from reusable robot modules.

Install

From a checkout:

pip install -e .

The package depends on jinja2 and the local motion-stack packages. In the full motion-stack workspace, install it with the workspace's normal package manager so those dependencies are available.

Generate a URDF

Assemblies combine modules such as Hero wheels, Hero arms, and Gustavo arms. For example, generate a cargo robot URDF in Python:

from moonbot_builder.assemblies import cargo_v2
from moonbot_builder.modules.hero import MhCargoV2, MhArmV3, MhWheelV2
from moonbot_builder.urdf.base import wrap_in_robot

urdf_fragment = cargo_v2.raw_urdf(
    left_wheel=MhWheelV2(1),
    right_wheel=MhWheelV2(2),
    left_arm=MhArmV3(3),
    right_arm=MhArmV3(4),
    cargo_box=MhCargoV2(1),
)

urdf = wrap_in_robot(urdf_fragment)
with open("moonbot.urdf", "w") as f:
    f.write(urdf)

Available assembly layouts include minimal, chain, vehicle, cargo, cargo_v2, dragon, tricycle, and triple_dragon. Inspect moonbot_builder/assemblies/ for their function signatures and available module combinations.

For a quick example, edit the selected assembly in moonbot_builder/assemblies/output.py and run:

python -m moonbot_builder.assemblies.output > moonbot.urdf

The generated URDF references meshes supplied by the corresponding asset packages. Those packages must be installed or sourced in the workspace before loading the URDF in a simulator or visualization tool.

Run the launch example

moonbot_builder.launch creates an assembly and starts its runtime nodes:

python -m moonbot_builder.launch

Useful options are:

python -m moonbot_builder.launch --rerun
python -m moonbot_builder.launch --fox
python -m moonbot_builder.launch --sim
python -m moonbot_builder.launch --backend rclpy

--rerun and --fox compile the first module's URDF and pass it to the corresponding visualizer. --sim uses the Newton simulator transport, which must be started separately. The default backend is pyzeros.

Main concepts

• modules/ defines robot parts and their runtime parameters.
• assemblies/ places modules together and compiles complete robots.
• urdf/ contains URDF helpers and asset-specific URDF builders.
• launch.py starts the generated level-1 nodes or visualization tools.