.xml → .urdf
MJCF to URDF
Convert a robot description from MJCF to URDF in the browser. Nothing is installed and nothing is queued: the file is read, written in the other format, and handed back with a list of anything that could not be carried across.
Convert a file
Drop your MJCF here
Drop the folder too if the model references meshes.
Files are read on our server and deleted after a day. Nothing is published.
Reading the MJCF
Writing the URDF
Look at the file first
What this conversion costs
These are the things URDF has no place for. They are reported on the converted file as well, as a comment at the top, so the file itself says what is missing from it.
- Anything MuJoCo adds that a robot description has no place for: solver settings, contact parameters, actuators, sensors, the floor and the lights.
- Free joints. A URDF has no way to say "this body floats" — the base becomes the root link and whatever held it up is gone.
MJCF describes a scene, URDF describes a robot
Everything in the file that is not the robot — the ground plane, the sky, the cameras — has nowhere to go and is dropped.
A kinematic tree, not a graph
URDF allows exactly one parent per link. A model with a closed loop cannot be written as URDF at all, and we say so rather than quietly cutting the loop.
The two formats
- MJCF .xml
- MuJoCo's own format: the same robot, plus everything a solver needs to simulate it.
- URDF .urdf
- the ROS description of a robot: links, joints, geometry and inertia, one rigid tree.
Converting is rarely the whole job. Once you have the URDF, the viewer shows what actually came across — collision geometry against visual, joint limits, where the mass sits — and the physics lab answers the question a file cannot: whether the robot stands up when gravity is switched on.