Sensors of type user no longer require objtype and objname. If unspecified, the objtype will be mjOBJ_UNKNOWN. Also, `user sensors datatype default is now "real"`.

PiperOrigin-RevId: 489652972
Change-Id: I0a8f21ee1a2f5292e6bbcfe3785536cfd1498b85

doc/XMLreference.rst

@@ -3913,7 +3913,7 @@ at a specified body, in global coordinates.
 .. _sensor-clock:
 
 :el-prefix:`sensor/` **clock** (*)
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 This element creates sensor that returns the simulation time.
 
@@ -3934,12 +3934,12 @@ bodies whose center of mass is of interest.
 
 :at:`name`, :at:`noise`, :at:`cutoff`, :at:`user`
    See :ref:`CSensor`.
-:at:`objtype`: :at-val:`(any element type that can be named), required`
+:at:`objtype`: :at-val:`(any element type that can be named), optional`
    Type of the MuJoCo object to which the sensor is attached. This together with the objname attribute determines the
-   actual object.
-:at:`objname`: :at-val:`string, required`
+   actual object. If unspecified, will be :ref:`mjOBJ_UNKNOWN<mjtObj>`.
+:at:`objname`: :at-val:`string, optional`
    Name of the MuJoCo object to which the sensor is attached.
-:at:`datatype`: :at-val:`[real, positive, axis, quaternion], required`
+:at:`datatype`: :at-val:`[real, positive, axis, quaternion], "real"`
    The type of output generated by this sensor. "axis" means a unit-length 3D vector. "quat" means a unit quaternion.
    These need to be declared because when MuJoCo adds noise, it must respect the vector normalization. "real" means a
    generic array (or scalar) of real values to which noise can be added independently.
@@ -3952,7 +3952,7 @@ bodies whose center of mass is of interest.
 .. _keyframe:
 
 **keyframe** (*)
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+~~~~~~~~~~~~~~~~
 
 This is a grouping element for keyframe definitions. It does not have attributes. Keyframes can be used to create a
 library of states that are of interest to the user, and to initialize the simulation state to one of the states in the

doc/changelog.rst

@@ -54,6 +54,8 @@ General
   ``dlopen`` on a POSIX system, and to ``LoadLibraryA`` on Windows. The second function scans a specified directory for
   all dynamic libraries file and loads each library found. Dynamic libraries opened by these functions are assumed to
   register one or more MuJoCo plugins on load.
+- Sensors of type :ref:`user<sensor-user>` no longer require :at:`objtype` and :at:`objname`. If unspecified, the
+  objtype will be :ref:`mjOBJ_UNKNOWN<mjtObj>`. ``user`` sensors :at:`datatype` default is now :at-val:`"real"`.
 
 Simulate
 ^^^^^^^^