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Add support for excluded contacts in adhesion actuators.

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- Update example model.
- Update video.

PiperOrigin-RevId: 468464196
Change-Id: I603c5a89c2d5a736de127440e6d542beffc12583
This commit is contained in:
Yuval Tassa
2022-08-18 08:27:42 -07:00
committed by Copybara-Service
parent 4bfc2c0311
commit 833dc74074
4 changed files with 111 additions and 50 deletions
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doc/XMLreference.rst
+16 -11
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@@ -3409,7 +3409,8 @@ helps clarify the role of bodies and geoms in MuJoCo.
assumption of uniform density. The internal default of 1000 is the density of water in SI units. This attribute is
used only when the mass attribute above is unspecified.
:at:`shellinertia` :at-val:`[false, true], "false"`
If true, the geom's inertia is computed assuming that all the mass is concentrated on the boundary. In this case :at:`density` is interpreted as surface density rather than volumetric density.
If true, the geom's inertia is computed assuming that all the mass is concentrated on the boundary. In this case
:at:`density` is interpreted as surface density rather than volumetric density.
:at:`solmix`: :at-val:`real, "1"`
This attribute specifies the weight used for averaging of contact parameters, and interacts with the priority
attribute. See :ref:`CContact`.
@@ -4616,18 +4617,22 @@ This element has nine custom attributes in addition to the common attributes:
:el-prefix:`actuator/` **adhesion** (*)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
.. youtube:: HdBue4MUZys
.. youtube:: BcHZ5BFeTmU
:align: right
:height: 200px
:height: 150px
This element defines an active adhesion actuator which injects force at contacts in the normal direction. On the right
is a video demonstrating this actuator type. The model shown in the video can be found `here
<https://github.com/deepmind/mujoco/tree/main/model/adhesion>`_. The transmission target is a :el:`body`, and adhesive
forces are injected into all contacts involving geoms which belong to this body. The force is divided equally between
multiple active contacts. Because it requires contact, it cannot apply a force at a distance, and is more like the active
adhesion on the feet of geckos and insects rather than an industrial vacuum gripper. Adhesion actuators' length is
always 0. :at:`ctrlrange` is required and must also be nonnegative (no repulsive forces are allowed). The underlying
:el:`general` attributes are set as follows:
This element defines an active adhesion actuator which injects forces at contacts in the normal direction, see
illustration video. The model shown in the video can be found `here
<https://github.com/deepmind/mujoco/tree/main/model/adhesion>`_ and includes inline annotations. The transmission target
is a :el:`body`, and adhesive forces are injected into all contacts involving geoms which belong to this body. The force
is divided equally between multiple contacts. When the :at:`gap` attribute is not used, this actuator requires active
contacts and cannot apply a force at a distance, more like the active adhesion on the feet of geckos and insects rather
than an industrial vacuum gripper. In order to enable "suction at a distance", "inflate" the body's geoms by
:at:`margin` and add a corresponding :at:`gap` which activates contacts only after :at:`gap` penetration distance. This
will create a layer around the geom where contacts are detected but are inactive, and can be used for
applying the adhesive force. In the video above, such inactive contacts are blue, while active contacts are orange.
An adhesion actuator's length is always 0. :at:`ctrlrange` is required and must also be nonnegative (no repulsive forces
are allowed). The underlying :el:`general` attributes are set as follows:
=========== ======= =========== ========
Attribute Setting Attribute Setting