# ANYmal B Description (MJCF)

Requires MuJoCo 2.2.2 or later.

## Overview

This package contains a simplified robot description (MJCF) of the [ANYmal B
robot](https://www.anybotics.com/anymal) developed by
[ANYbotics](https://www.anybotics.com). It is derived from the [publicly
available URDF
description](https://github.com/ANYbotics/anymal_b_simple_description).

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

## URDF → MJCF derivation steps

1. Converted the DAE [mesh
   files](https://github.com/ANYbotics/anymal_b_simple_description/tree/master/meshes)
   to OBJ format using [Blender](https://www.blender.org/).
2. Processed `.obj` files with [`obj2mjcf`](https://github.com/kevinzakka/obj2mjcf).
3. Added `<mujoco> <compiler discardvisual="false"/> </mujoco>` to the
   [URDF](https://github.com/ANYbotics/anymal_b_simple_description/blob/master/urdf/anymal.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, and a tracking light.
6. Manually edited the MJCF to extract common properties into the `<default>` section.
7. Added `<exclude>` clauses to prevent collisions between the base and the thighs.
8. Added position-controlled actuators, roughly corresponding to the motor spec
   [here](https://doi.org/10.1080/01691864.2017.1378591).
9. Added joint damping to correspond to D gains of the same spec.
10. Added joint frictionloss to correspond to torque resolution of the same spec.
11. Softened the contacts of the feet to approximate the effect of rubber.
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).

## Publications

If you use this work in an academic context, please cite the following publications:

> M. Hutter, C. Gehring, A. Lauber, F. Gunther, C. D. Bellicoso, V. Tsounis, P. Fankhauser, R. Diethelm, S. Bachmann, M. Bloesch, H. Kolvenbach, M. Bjelonic, L. Isler and K. Meyer
> **"ANYmal - toward legged robots for harsh environments“**,
> in Advanced Robotics, 31.17, 2017. ([DOI](https://doi.org/10.1080/01691864.2017.1378591))

    @article{anymal2017,
        title={ANYmal-toward legged robots for harsh environments},
        author={Hutter, Marco and Gehring, Christian and Lauber, Andreas and Gunther, Fabian and Bellicoso, Carmine Dario and Tsounis, Vassilios and Fankhauser, P{\'e}ter and Diethelm, Remo and Bachmann, Samuel and Bl{\"o}sch, Michael and Kolvenbach, Hendrik and Bjelonic, Marko and Isler, Linus and Meyer, Konrad},
        journal={Advanced Robotics},
        volume={31},
        number={17},
        pages={918--931},
        year={2017},
        publisher={Taylor \& Francis}
    }

> ANYbotics,
> **"ANYmal – Autonomous Legged Robot“**,
> [https://www.anybotics.com/anymal](https://www.anybotics.com/anymal) (accessed: 01.01.2019)

    @misc{anymal,
        author = {ANYbotics},
        title = {{ANYmal - Autonomous Legged Robot}},
        howpublished = {\url{https://www.anybotics.com/anymal}},
        note = {Accessed: 2019-01-01}
    }