Add muscle actuators to MJX.

PiperOrigin-RevId: 695334356
Change-Id: I6590ed6bdd4a8adc53d5c4e2641f472f7439cedc

doc/changelog.rst

@@ -6,6 +6,10 @@ Changelog
 Upcoming version (not yet released)
 -----------------------------------
 
+MJX
+^^^
+- Added muscle actuators.
+
 Bug fixes
 ^^^^^^^^^
 - Fixed :github:issue:`2212`, type error in ``mjx.get_data``.

doc/mjx.rst

@@ -214,11 +214,11 @@ The following features are **fully supported** in MJX:
    * - :ref:`Transmission <mjtTrn>`
      - ``JOINT``, ``JOINTINPARENT``, ``SITE``, ``TENDON``
    * - :ref:`Actuator Dynamics <mjtDyn>`
-     - ``NONE``, ``INTEGRATOR``, ``FILTER``, ``FILTEREXACT``
+     - ``NONE``, ``INTEGRATOR``, ``FILTER``, ``FILTEREXACT``, ``MUSCLE``
    * - :ref:`Actuator Gain <mjtGain>`
-     - ``FIXED``, ``AFFINE``
+     - ``FIXED``, ``AFFINE``, ``MUSCLE``
    * - :ref:`Actuator Bias <mjtBias>`
-     - ``NONE``, ``AFFINE``
+     - ``NONE``, ``AFFINE``, ``MUSCLE``
    * - :ref:`Tendon Wrapping <mjtWrap>`
      - ``JOINT``, ``SITE``, ``PULLEY``
    * - :ref:`Geom <mjtGeom>`
@@ -264,12 +264,6 @@ The following features are **in development** and coming soon:
      - ``IMPLICIT``
    * - Dynamics
      - :ref:`Inverse <mj_inverse>`
-   * - :ref:`Actuator Dynamics <mjtDyn>`
-     - ``MUSCLE``
-   * - :ref:`Actuator Gain <mjtGain>`
-     - ``MUSCLE``
-   * - :ref:`Actuator Bias <mjtBias>`
-     - ``MUSCLE``
    * - :ref:`Tendon Wrapping <mjtWrap>`
      - ``SPHERE``, ``CYLINDER``
    * - Fluid Model