# WidowX 250 6DOF Description (MJCF)

> [!IMPORTANT]
> Requires MuJoCo 3.1.6 or later.

## Overview

This package contains a simplified robot description (MJCF) of the [WidowX 250 6DOF](https://www.trossenrobotics.com/widowx-250) developed by [Trossen Robotics](https://www.trossenrobotics.com/). It is derived from the [publicly available URDF description](https://github.com/Interbotix/interbotix_ros_manipulators/blob/main/interbotix_ros_xsarms/interbotix_xsarm_descriptions/urdf/wx250s.urdf.xacro).

<p float="left">
  <img src="wx250s.png" width="400">
</p>

## URDF → MJCF derivation steps

1. Added `<mujoco> <compiler discardvisual="false" strippath="false" fusestatic="false"/> </mujoco>` to the URDF's
   `<robot>` clause in order to preserve visual geometries.
2. Loaded the URDF into MuJoCo and saved a corresponding MJCF.
3. Manually edited the MJCF to extract common properties into the `<default>` section.
4. Used [`interbotix_black.png`](https://github.com/Interbotix/interbotix_ros_manipulators/blob/main/interbotix_ros_xsarms/interbotix_xsarm_descriptions/meshes/interbotix_black.png) to texture the visual geoms.
5. Added a light to track `gripper_link`.
6. Removed `gripper` joint.
7. Added an equality constraint so that the right finger mimics the position of the left finger.
8. Added extra sphere collision geoms to the gripper for additional contact points.
9. Added `exclude` clause to prevent collisions between `base_link` and `shoulder_link`.
10. Added position controlled actuators.
    * Removed all `actuatorfrcrange` as they were extremely low and affecting the actuation.
11. Added `impratio=10` and `cone=elliptic` for better noslip.
12. Added `scene.xml` which includes the robot, with a textured groundplane, skybox, and haze.

## License

This model is released under a [BSD-3-Clause License](LICENSE).