MCJF_warp — URDF to MuJoCo MJCF Converter

Converts robot URDF files to MuJoCo MJCF format. Adds ground plane and lighting.

Requirements

Install MuJoCo (Linux — minimal steps)

Create and activate a Python venv, install the Python package and system GL deps:

python3 -m venv ~/mujoco_env
source ~/mujoco_env/bin/activate
pip install --upgrade pip
pip install mujoco pyyaml

Usage

python3 MCJF_warp.py --config sample.yaml

Config (YAML)

Field	Required	Description
model_path	✓	Path to robot .urdf or .xml
output_path	✓	Output .xml path
mesh_dir	✓	Directory containing mesh files
package_map	✗	Maps package:// URIs to filesystem paths

model_path:  "/path/to/robot.urdf"
output_path: "./robot_clean.xml"
mesh_dir:    "/path/to/meshes"

package_map:                          # optional
  my_package: "/path/to/my_package"

Path formats supported

Format	Example
Absolute	/home/user/robot.urdf
Relative	./robot.urdf
Env var	${CONDA_PREFIX}/share/robot.urdf
Home dir	~/robot.urdf

Pipeline

Phase 1 → Load & validate YAML config
Phase 2 → Resolve package:// URIs → save resolved URDF
Phase 3 → MuJoCo converts URDF → MJCF, adds ground + lights
Phase 4 → Validate with MuJoCo
Phase 5 → Export final MJCF
Phase 6 → Print summary

Intermediate Files (in mesh_dir)

File	Description
*_resolved.urdf	URDF after URI resolution
*_temp.xml	Raw MuJoCo output
*_scene.xml	MJCF with ground + lights

View Output

python3 -m mujoco.viewer robot_clean.xml

Troubleshooting

Error	Fix
Config not found	Check YAML path
Model not found	Check model_path in YAML
Mesh dir not found	Check mesh_dir in YAML
Unresolved packages	Add missing package to package_map
MuJoCo load failed	Check all meshes exist in mesh_dir

Supported Formats

Format	Input	Notes
URDF	✓	Primary format
MJCF	✓	MuJoCo native
SDF	✗	Not supported by MuJoCo directly

Adding a New Robot

cp sample.yaml my_robot.yaml
# edit my_robot.yaml
python3 MCJF_warp.py --config my_robot.yaml