Merge pull request #49 from cwstryker/cwstryker/add-profiledpidsubsystem

Ported the ProfiledPIDSubsystem from the wpilib java source to Python

Author: virtuald

Diff for: commands2/__init__.py

@@ -16,6 +16,7 @@
 from .pidcommand import PIDCommand
 from .pidsubsystem import PIDSubsystem
 from .printcommand import PrintCommand
+from .profiledpidsubsystem import ProfiledPIDSubsystem
 from .proxycommand import ProxyCommand
 from .repeatcommand import RepeatCommand
 from .runcommand import RunCommand
@@ -51,6 +52,7 @@
     "PIDCommand",
     "PIDSubsystem",
     "PrintCommand",
+    "ProfiledPIDSubsystem",
     "ProxyCommand",
     "RepeatCommand",
     "RunCommand",

Diff for: commands2/profiledpidsubsystem.py

@@ -0,0 +1,78 @@
+# Copyright (c) FIRST and other WPILib contributors.
+# Open Source Software; you can modify and/or share it under the terms of
+# the WPILib BSD license file in the root directory of this project.
+
+from typing import Union, cast
+
+from wpimath.trajectory import TrapezoidProfile
+
+from .subsystem import Subsystem
+
+
+class ProfiledPIDSubsystem(Subsystem):
+    """
+    A subsystem that uses a :class:`wpimath.controller.ProfiledPIDController`
+    or :class:`wpimath.controller.ProfiledPIDControllerRadians` to
+    control an output. The controller is run synchronously from the subsystem's
+    :meth:`.periodic` method.
+    """
+
+    def __init__(
+        self,
+        controller,
+        initial_position: float = 0,
+    ):
+        """Creates a new PIDSubsystem."""
+        super().__init__()
+        self._controller = controller
+        self._enabled = False
+        self.setGoal(initial_position)
+
+    def periodic(self):
+        """Updates the output of the controller."""
+        if self._enabled:
+            self.useOutput(
+                self._controller.calculate(self.getMeasurement()),
+                self._controller.getSetpoint(),
+            )
+
+    def getController(
+        self,
+    ):
+        """Returns the controller"""
+        return self._controller
+
+    def setGoal(self, goal):
+        """
+        Sets the goal state for the subsystem.
+        """
+        self._controller.setGoal(goal)
+
+    def useOutput(self, output: float, setpoint: TrapezoidProfile.State):
+        """
+        Uses the output from the controller object.
+        """
+        raise NotImplementedError(f"{self.__class__} must implement useOutput")
+
+    def getMeasurement(self) -> float:
+        """
+        Returns the measurement of the process variable used by the
+        controller object.
+        """
+        raise NotImplementedError(f"{self.__class__} must implement getMeasurement")
+
+    def enable(self):
+        """Enables the PID control. Resets the controller."""
+        self._enabled = True
+        self._controller.reset(self.getMeasurement())
+
+    def disable(self):
+        """Disables the PID control. Sets output to zero."""
+        self._enabled = False
+        self.useOutput(0, TrapezoidProfile.State())
+
+    def isEnabled(self) -> bool:
+        """
+        Returns whether the controller is enabled.
+        """
+        return self._enabled

Diff for: tests/test_profiledpidsubsystem.py

@@ -0,0 +1,119 @@
+from types import MethodType
+from typing import Any
+
+import pytest
+from wpimath.controller import ProfiledPIDController, ProfiledPIDControllerRadians
+from wpimath.trajectory import TrapezoidProfile, TrapezoidProfileRadians
+
+from commands2 import ProfiledPIDSubsystem
+
+MAX_VELOCITY = 30  # Radians per second
+MAX_ACCELERATION = 500  # Radians per sec squared
+PID_KP = 50
+
+
+class EvalSubsystem(ProfiledPIDSubsystem):
+    def __init__(self, controller, state_factory):
+        self._state_factory = state_factory
+        super().__init__(controller, 0)
+
+
+def simple_use_output(self, output: float, setpoint: Any):
+    """A simple useOutput method that saves the current state of the controller."""
+    self._output = output
+    self._setpoint = setpoint
+
+
+def simple_get_measurement(self) -> float:
+    """A simple getMeasurement method that returns zero (frozen or stuck plant)."""
+    return 0.0
+
+
+controller_types = [
+    (
+        ProfiledPIDControllerRadians,
+        TrapezoidProfileRadians.Constraints,
+        TrapezoidProfileRadians.State,
+    ),
+    (ProfiledPIDController, TrapezoidProfile.Constraints, TrapezoidProfile.State),
+]
+controller_ids = ["radians", "dimensionless"]
+
+
+@pytest.fixture(params=controller_types, ids=controller_ids)
+def subsystem(request):
+    """
+    Fixture that returns an EvalSubsystem object for each type of controller.
+    """
+    controller, profile_factory, state_factory = request.param
+    profile = profile_factory(MAX_VELOCITY, MAX_ACCELERATION)
+    pid = controller(PID_KP, 0, 0, profile)
+    return EvalSubsystem(pid, state_factory)
+
+
+def test_profiled_pid_subsystem_init(subsystem):
+    """
+    Verify that the ProfiledPIDSubsystem can be initialized using
+    all supported profiled PID controller / trapezoid profile types.
+    """
+    assert isinstance(subsystem, EvalSubsystem)
+
+
+def test_profiled_pid_subsystem_not_implemented_get_measurement(subsystem):
+    """
+    Verify that the ProfiledPIDSubsystem.getMeasurement method
+    raises NotImplementedError.
+    """
+    with pytest.raises(NotImplementedError):
+        subsystem.getMeasurement()
+
+
+def test_profiled_pid_subsystem_not_implemented_use_output(subsystem):
+    """
+    Verify that the ProfiledPIDSubsystem.useOutput method raises
+    NotImplementedError.
+    """
+    with pytest.raises(NotImplementedError):
+        subsystem.useOutput(0, subsystem._state_factory())
+
+
+@pytest.mark.parametrize("use_float", [True, False])
+def test_profiled_pid_subsystem_set_goal(subsystem, use_float):
+    """
+    Verify that the ProfiledPIDSubsystem.setGoal method sets the goal.
+    """
+    if use_float:
+        subsystem.setGoal(1.0)
+        assert subsystem.getController().getGoal().position == 1.0
+        assert subsystem.getController().getGoal().velocity == 0.0
+    else:
+        subsystem.setGoal(subsystem._state_factory(1.0, 2.0))
+        assert subsystem.getController().getGoal().position == 1.0
+        assert subsystem.getController().getGoal().velocity == 2.0
+
+
+def test_profiled_pid_subsystem_enable_subsystem(subsystem):
+    """
+    Verify the subsystem can be enabled.
+    """
+    # Dynamically add useOutput and getMeasurement methods so the
+    # system can be enabled
+    setattr(subsystem, "useOutput", MethodType(simple_use_output, subsystem))
+    setattr(subsystem, "getMeasurement", MethodType(simple_get_measurement, subsystem))
+    # Enable the subsystem
+    subsystem.enable()
+    assert subsystem.isEnabled()
+
+
+def test_profiled_pid_subsystem_disable_subsystem(subsystem):
+    """
+    Verify the subsystem can be disabled.
+    """
+    # Dynamically add useOutput and getMeasurement methods so the
+    # system can be enabled
+    setattr(subsystem, "useOutput", MethodType(simple_use_output, subsystem))
+    setattr(subsystem, "getMeasurement", MethodType(simple_get_measurement, subsystem))
+    # Enable and then disable the subsystem
+    subsystem.enable()
+    subsystem.disable()
+    assert not subsystem.isEnabled()