Add Stretch 3 MJCF description.

CHANGELOG.md

@@ -14,6 +14,7 @@ All notable changes to this project will be documented in this file.
 
 ### Added
 
+- Description: Stretch 3 (MJCF) (thanks to @kevinzakka)
 - Description: Shadow DEX-EE (MJCF) (thanks to @kevinzakka)
 - Description: KUKA iiwa 7 (URDF)
 - Description: Unitree G1 (MJCF) (thanks to @kevinzakka)

README.md

@@ -240,6 +240,7 @@ The DOF column denotes the number of actuated degrees of freedom.
 | `reachy_description`          | Reachy                | Pollen Robotics          | 21  | URDF       |
 | `stretch_description`         | Stretch RE1           | Hello Robot              | 14  | URDF       |
 | `sretch_mj_description`       | Stretch 2             | Hello Robot              | 14  | MJCF       |
+| `sretch_3_mj_description`     | Stretch 3             | Hello Robot              | 14  | MJCF       |
 | `tiago_description`           | TIAGo                 | PAL Robotics             | 48  | URDF       |
 
 ### Quadrupeds

robot_descriptions/stretch_3_mj_description.py

@@ -0,0 +1,20 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+#
+# SPDX-License-Identifier: Apache-2.0
+
+"""Stretch 3 description."""
+
+from os import getenv as _getenv
+from os import path as _path
+
+from ._cache import clone_to_cache as _clone_to_cache
+
+REPOSITORY_PATH: str = _clone_to_cache(
+    "mujoco_menagerie",
+    commit=_getenv("ROBOT_DESCRIPTION_COMMIT", None),
+)
+
+PACKAGE_PATH: str = _path.join(REPOSITORY_PATH, "hello_robot_stretch_3")
+
+MJCF_PATH: str = _path.join(PACKAGE_PATH, "stretch.xml")