Add Low-cost robot arm MJCF description

Author: stephane-caron

CHANGELOG.md

@@ -6,8 +6,9 @@ All notable changes to this project will be documented in this file.
 
 ### Added
 
-- Description: Kinova Gen3 Lite (URDF)
 - Description: ARX L5 (MJCF) (thanks to @jonzamora)
+- Description: Kinova Gen3 Lite (URDF)
+- Description: Low-cost robot arm (MJCF)
 
 ### Changed
 

README.md

@@ -146,6 +146,7 @@ The DOF column denotes the number of actuated degrees of freedom.
 | `iiwa14_description`          | iiwa 14               | KUKA                     | URDF       | BSD-3-Clause |
 | `iiwa14_mj_description`       | iiwa 14               | KUKA                     | MJCF       | BSD-3-Clause |
 | `iiwa7_description`           | iiwa 7                | KUKA                     | URDF       | MIT          |
+| `low_cost_robot_arm_mj_description` | Low-cost robot arm | Alexander Koch | MJCF | [Apache-2.0](https://github.com/google-deepmind/mujoco_menagerie/blob/ef4d04fbb7451d30b39c2aff7e49df737bb46815/low_cost_robot_arm/LICENSE) |
 | `panda_description`           | Panda                 | Franka Robotics          | URDF       | Apache-2.0   |
 | `panda_mj_description`        | Panda                 | Franka Robotics          | MJCF       | Apache-2.0   |
 | `piper_description`           | PiPER                 | AgileX                   | URDF       | MIT          |

robot_descriptions/_descriptions.py

@@ -134,6 +134,9 @@ def has_urdf(self) -> bool:
     "leap_hand_mj_description": Description(
         Format.MJCF, tags={"end_effector"}
     ),
+    "low_cost_robot_arm_mj_description": Description(
+        Format.MJCF, tags={"arm"}
+    ),
     "mini_cheetah_description": Description(Format.URDF, tags={"quadruped"}),
     "minitaur_description": Description(Format.URDF, tags={"quadruped"}),
     "nextage_description": Description(Format.URDF, tags={"dual_arm"}),

robot_descriptions/_repositories.py

@@ -177,7 +177,7 @@ class Repository:
     ),
     "mujoco_menagerie": Repository(
         url="https://github.com/deepmind/mujoco_menagerie.git",
-        commit="e44555e5a6478f5119dfd5ca9c4a8270ae1b9933",
+        commit="ef4d04fbb7451d30b39c2aff7e49df737bb46815",
         cache_path="mujoco_menagerie",
     ),
     "nao_robot": Repository(

robot_descriptions/low_cost_robot_arm_mj_description.py

@@ -0,0 +1,21 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+#
+# SPDX-License-Identifier: Apache-2.0
+# Copyright 2025 Inria
+
+"""Low-cost robot arm MJCF 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, "low_cost_robot_arm")
+
+MJCF_PATH: str = _path.join(PACKAGE_PATH, "low_cost_robot_arm.xml")