pybricks.common.Motor: Add Model() class instance.

This is mainly used to debug the motor model, and to quickly select the
feedback parameters. This is useful when adding or configuring new motor
types.

Reading the estimated speed can also be useful in advanced applications
where the user builds their own PID controller.

We may choose to hide this method from the documentation before the
release.

CHANGELOG.md

@@ -6,6 +6,8 @@
 
 ### Added
 - Documented ``integral_deadzone`` in ``Control.pid()``.
+- Documented ``Motor.model``. This can be used to view the estimated motor
+  state and change its settings.
 
 ## 3.2.0 - 2022-12-20
 

doc/main/pupdevices/motor.rst

@@ -93,6 +93,14 @@ Motors with rotation sensors
         The :meth:`done`, :meth:`stalled` and :meth:`load` methods have been
         moved.
 
+    .. pybricks-requirements:: pybricks-common-control
+
+    .. automethod:: pybricks.pupdevices.Motor.model.state
+
+    .. pybricks-requirements:: pybricks-common-control
+
+    .. automethod:: pybricks.pupdevices.Motor.model.settings
+
 Initialization examples
 -----------------------
 

src/pybricks/_common.py

@@ -304,6 +304,52 @@ def stall_tolerances(self, speed, time):
         """
 
 
+class Model:
+    """Class to interact with motor state observer and settings."""
+
+    def state(self) -> Tuple[float, float, float, bool]:
+        """state() -> Tuple[float, float, float, bool]
+
+        Gets the estimated angle, speed, current, and stall state of the motor,
+        using a simulation model that mimics the real motor.
+        These estimates are updated faster than the real measurements,
+        which can be useful when building your own PID controllers.
+
+        For most applications it is better to used the *measured*
+        :meth:`angle <pybricks.pupdevices.Motor.angle>`,
+        :meth:`speed <pybricks.pupdevices.Motor.speed>`,
+        :meth:`load <pybricks.pupdevices.Motor.load>`, and
+        :meth:`stall <pybricks.pupdevices.Motor.stalled>` state instead.
+
+        Returns:
+            Tuple with the estimated angle (deg), speed (deg/s), current (mA),
+            and stall state (``True`` or ``False``).
+        """
+
+    @overload
+    def settings(self, values: tuple) -> None:
+        ...
+
+    @overload
+    def settings(self) -> tuple:
+        ...
+
+    def settings(self, speed, time):
+        """settings(values)
+        settings() -> Tuple
+
+        Gets or sets model settings as a tuple of integers. If no arguments are
+        given, this will return the current values. This method is mainly used
+        to debug the motor model class. Changing these settings should not be
+        needed in user programs.
+
+        .. _model settings: https://docs.pybricks.com/projects/pbio/en/latest/struct__pbio__observer__settings__t.html
+
+        Arguments:
+            values (Tuple): Tuple with `model settings`_.
+        """
+
+
 class Motor(DCMotor):
     """Generic class to control motors with built-in rotation sensors."""
 
@@ -313,6 +359,9 @@ class Motor(DCMotor):
     ``control`` attribute of the motor. See :ref:`control` for an overview
     of available methods."""
 
+    model = Model()
+    """Model representing the observer that estimates the motor state."""
+
     def __init__(
         self,
         port: Port,