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Improvements related to models where joint-actuator relationship is not one-to-one:

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- Add `joint-actuatorforcerange` for clamping total actuator force at joints. Add `sensor-jointactuatorfrc` for sensing total actuator forces on a single joint.
See [documentation](https://mujoco.readthedocs.io/en/latest//modeling.html#actuator-force-clamping) for justification and use cases.
- Add simple car model to `model/`.
- Move actuation-related test models into `engine/testdata/actuation/`.

PiperOrigin-RevId: 549355941
Change-Id: I27f6c1f80426d73a2811ef5ae74684a228b2fbd1
This commit is contained in:
Yuval Tassa
2023-07-19 10:28:24 -07:00
committed by Copybara-Service
parent 7603b07a20
commit 51aa375af0
29 changed files with 453 additions and 105 deletions
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doc/XMLreference.rst
+52 -1
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@@ -1421,6 +1421,8 @@ if omitted.
.. _default-joint-limited:
.. _default-joint-actuatorforcelimited:
.. _default-joint-solreflimit:
.. _default-joint-solimplimit:
@@ -1433,6 +1435,8 @@ if omitted.
.. _default-joint-range:
.. _default-joint-actuatorforcerange:
.. _default-joint-margin:
.. _default-joint-ref:
@@ -3053,6 +3057,16 @@ unit quaternions.
attribute is "auto", and :at:`autolimits` is set in :ref:`compiler <compiler>`, joint limits will be enabled
if range is defined.
.. _body-joint-actuatorforcelimited:
:at:`actuatorforcelimited`: :at-val:`[false, true, auto], "auto"`
This attribute specifies whether actuator forces acting on the joint should be clamped. See :ref:`CForceRange` for
details. It is available only for scalar joints (hinge and slider) and ignored for ball and free joints. |br| This
attribute interacts with the actuatorforcerange attribute below. If this attribute is "false", actuator force
clamping is disabled. If it is "true", actuator force clamping is enabled. If this attribute is "auto", and
:at:`autolimits` is set in :ref:`compiler <compiler>`, actuator force clamping will be enabled if actuatorforcerange
is defined.
.. _body-joint-solreflimit:
.. _body-joint-solimplimit:
@@ -3084,6 +3098,14 @@ unit quaternions.
|br| Setting this attribute without specifying :at:`limited` is an error, unless :at:`autolimits` is set in
:ref:`compiler <compiler>`.
.. _body-joint-actuatorforcerange:
:at:`actuatorforcerange`: :at-val:`real(2), "0 0"`
Range for clamping total actuator forces acting on this joint. See :ref:`CForceRange` for details. It is available
only for scalar joints (hinge and slider) and ignored for ball and free joints. |br| The compiler expects the first
value to be smaller than the second value. |br| Setting this attribute without specifying :at:`actuatorforcelimited`
is an error, unless :at:`compiler-autolimits` is set.
.. _body-joint-margin:
:at:`margin`: :at-val:`real, "0"`
@@ -5009,7 +5031,8 @@ specify them independently.
:at:`refsite`: :at-val:`string, optional`
When using a :at:`site` transmission, measure the translation and rotation w.r.t the frame of the :at:`refsite`. In
this case the actuator *does* have length and :el:`position` actuators can be used to directly control an end
effector, see `refsite.xml <https://github.com/deepmind/mujoco/tree/main/test/engine/testdata/refsite.xml>`_ example
effector, see `refsite.xml
<https://github.com/deepmind/mujoco/tree/main/test/engine/testdata/actuation/refsite.xml>`__ example
model. As above, the length is the dot product of the :at:`gear` vector and the frame difference. So ``gear="0 1 0 0
0 0"`` means "Y-offset of :at:`site` in the :at:`refsite` frame", while ``gear="0 0 0 0 0 1"`` means rotation "Z-
rotation of :at:`site` in the :at:`refsite` frame". It is recommended to use a normalized :at:`gear` vector with
@@ -6217,6 +6240,34 @@ arms determined by the transmission). This sensor can be attached to any actuato
The actuator whose scalar force output will be sensed. The sensor output is copied from mjData.actuator_force.
.. _sensor-jointactuatorfrc:
:el-prefix:`sensor/` |-| **jointactuatorfrc** (*)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
This element creates an actuator force sensor, measured at a joint. The quantity being sensed is the
generalized force contributed by all actuators to a single scalar joint (hinge or slider). This type of sensor is
important when multiple actuators act on a single joint or when a single actuator act on multiple joints. See
:ref:`CForceRange` for details.
.. _sensor-jointactuatorfrc-name:
.. _sensor-jointactuatorfrc-noise:
.. _sensor-jointactuatorfrc-cutoff:
.. _sensor-jointactuatorfrc-user:
:at:`name`, :at:`noise`, :at:`cutoff`, :at:`user`
See :ref:`CSensor`.
.. _sensor-jointactuatorfrc-joint:
:at:`joint`: :at-val:`string, required`
The joint where actuator forces will be sensed. The sensor output is copied from ``mjData.qfrc_actuator``.
.. _sensor-ballquat:
:el-prefix:`sensor/` |-| **ballquat** (*)