LuckyWorld/SourceFiles/mujoco_menagerie-main/unitree_go2

Unitree Go2 Description (MJCF)

Important

Requires MuJoCo 2.2.2 or later.

Changelog

• 16/02/2025: Make actuator order match joint order.
• 01/06/2024: Fix foot solimp.
• 23/10/2023: Initial release.

Overview

This package contains a simplified robot description (MJCF) of the Go2 Quadruped Robot developed by Unitree Robotics. It is derived from the publicly available URDF description.

URDF → MJCF derivation steps

1. Converted the DAE mesh files to OBJ format using Blender.
   • When exporting, ensure "up axis" is +Z, and "forward axis" is +Y.
2. Processed .obj files with obj2mjcf.
3. Added <mujoco> <compiler discardvisual="false" strippath="false" fusestatic="false"/> </mujoco> to the URDF's <robot> clause in order to preserve visual geometries.
4. Loaded the URDF into MuJoCo and saved a corresponding MJCF.
5. Added a <freejoint/> to the base.
6. Manually edited the MJCF to extract common properties into the <default> section.
7. Softened the contacts of the feet to approximate the effect of rubber and increased impratio to reduce slippage.
8. Added scene.xml which includes the robot, with a textured groundplane, skybox, and haze.

MJX

A version of the Unitree Go2 model for use in MJX is available in scene_mjx.xml with the following changes:

1. The solver iterations and ls_iterations were modified for performance.
2. frictionloss was removed.
3. The friction cone was changed from elliptic to pyramidal.
4. All contacts other than the sphere geoms were changed to sphere geoms and placed at the joints positions to simulate collisions at critical locations.
   • Note: Currently, MJX cannot deal with collision geoms other than spheres. In this case, we have to put many collision spheres in critical locations of the robot such as joints, torso, and feet as illustrated below.

License

This model is released under a BSD-3-Clause License.

Acknowledgments

The MJX model of Go2 was contributed by lonelyfluency.