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Add defaults to SDF plugin attributes.

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Expose diameter and number of teeth for the gear SDF.

PiperOrigin-RevId: 577779297
Change-Id: Iec5890ab7f39080b395cf06a76f9c2216f4f39ed
This commit is contained in:
Alessio Quaglino
2023-10-30 03:08:41 -07:00
committed by Copybara-Service
parent c921c3956e
commit 50843cad30
18 changed files with 341 additions and 97 deletions
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doc/programming/extension.rst
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@@ -250,20 +250,24 @@ A future version of this section will include:
Currently, there are three directories of first-party plugins:
* **elasticity:** The plugins in the `elasticity/ <https://github.com/google-deepmind/mujoco/tree/main/plugin/elasticity>`__
directory are passive forces based on continuum mechanics for 1-dimensional and 3-dimensional bodies. The
1D model is invariant under rotations and captures the large deformation of elastic cables, decoupling twisting and
bending strains. The 3D solid is a
`Saint Venant-Kirchhoff <https://en.wikipedia.org/wiki/Hyperelastic_material#Saint_Venant%E2%80%93Kirchhoff_model>`__
model discretized with piecewise linear finite elements, which is suitable for large deformations with small strains.
See also :ref:`composite <CComposite>` and :ref:`deformable <CDeformable>` objects.
* **elasticity:** The plugins in the `elasticity/
<https://github.com/google-deepmind/mujoco/tree/main/plugin/elasticity>`__ directory are passive forces based on
continuum mechanics for 1-dimensional and 3-dimensional bodies. The 1D model is invariant under rotations and captures
the large deformation of elastic cables, decoupling twisting and bending strains. The 3D solid is a `Saint
Venant-Kirchhoff <https://en.wikipedia.org/wiki/Hyperelastic_material#Saint_Venant%E2%80%93Kirchhoff_model>`__ model
discretized with piecewise linear finite elements, which is suitable for large deformations with small strains. See
also :ref:`composite <CComposite>` and :ref:`deformable <CDeformable>` objects. For more information, please see the
`README <https://github.com/google-deepmind/mujoco/blob/main/plugin/elasticity/README.md>`__.
* **sensor:** The plugins in the `sensor/ <https://github.com/google-deepmind/mujoco/tree/main/plugin/sensor>`__
directory implement custom sensors. Currently the sole sensor plugin is the touch grid sensor, see the
`README <https://github.com/google-deepmind/mujoco/blob/main/plugin/sensor/README.md>`__ for details.
* **sdf:** The plugins in the `sdf/ <https://github.com/google-deepmind/mujoco/tree/main/plugin/sdf>`__
directory specify custom shapes in a mesh-free manner, by defining methods computing a signed distance field and its
gradient at query points. This shape then acts as a new geom type in the collision table at the top of
`engine_collision_driver.c <https://github.com/google-deepmind/mujoco/blob/main/src/engine/engine_collision_driver.c>`__.
* **sdf:** The plugins in the `sdf/ <https://github.com/google-deepmind/mujoco/tree/main/plugin/sdf>`__ directory
specify custom shapes in a mesh-free manner, by defining methods computing a signed distance field and its gradient at
query points. This shape then acts as a new geom type in the collision table at the top of `engine_collision_driver.c
<https://github.com/google-deepmind/mujoco/blob/main/src/engine/engine_collision_driver.c>`__. For more information
concerning the available SDFs and how to write your own implicit geometry, please see the `README
<https://github.com/google-deepmind/mujoco/blob/main/plugin/sdf/README.md>`__. The rest of this section will give more
detail concerning the collision algorithm and the plugin engine interface.
Collision points are found by minimizing the maximum of the two colliding SDFs via gradient descent.
Because SDFs are non-convex, multiple starting points are required in order to converge to multiple local minima.