allwpilib/robotpyExamples/FlywheelBangBangController/robot.py

#!/usr/bin/env python3
#
# 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.
#

import wpilib
import math

import wpilib.simulation
import wpimath
import wpimath.units


class MyRobot(wpilib.TimedRobot):
    """
    This is a sample program to demonstrate the use of a BangBangController with a flywheel to
    control RPM.
    """

    kMotorPort = 0
    kEncoderAChannel = 0
    kEncoderBChannel = 1

    # Max setpoint for joystick control in RPM
    kMaxSetpointValue = 6000.0

    # Gains are for example purposes only - must be determined for your own robot!
    kFlywheelKs = 0.0001  # V
    kFlywheelKv = 0.000195  # V/RPM
    kFlywheelKa = 0.0003  # V/(RPM/s)

    # Reduction between motors and encoder, as output over input. If the flywheel
    # spins slower than the motors, this number should be greater than one.
    kFlywheelGearing = 1.0

    # 1/2 MR²
    kFlywheelMomentOfInertia = (
        0.5
        * wpimath.units.lbsToKilograms(1.5)
        * math.pow(wpimath.units.inchesToMeters(4), 2)
    )

    def __init__(self) -> None:
        """Robot initialization function"""
        super().__init__()

        self.flywheelMotor = wpilib.PWMSparkMax(self.kMotorPort)
        self.encoder = wpilib.Encoder(self.kEncoderAChannel, self.kEncoderBChannel)

        self.bangBangControler = wpimath.BangBangController()

        # Gains are for example purposes only - must be determined for your own robot!
        self.feedforward = wpimath.SimpleMotorFeedforwardMeters(
            self.kFlywheelKs, self.kFlywheelKv, self.kFlywheelKa
        )

        # Joystick to control setpoint
        self.joystick = wpilib.Joystick(0)

        # Simulation classes help us simulate our robot

        self.gearbox = wpimath.DCMotor.NEO(1)

        self.plant = wpimath.Models.flywheelFromPhysicalConstants(
            self.gearbox, self.kFlywheelGearing, self.kFlywheelMomentOfInertia
        )

        self.flywheelSim = wpilib.simulation.FlywheelSim(self.plant, self.gearbox)
        self.encoderSim = wpilib.simulation.EncoderSim(self.encoder)

        # Add bang-bang controller to SmartDashboard and networktables.
        wpilib.SmartDashboard.putData(self.bangBangControler)

    def teleopPeriodic(self) -> None:
        """Controls flywheel to a set speed (RPM) controlled by a joystick."""

        # Scale setpoint value between 0 and maxSetpointValue
        setpoint = max(
            0.0,
            self.joystick.getRawAxis(0)
            * wpimath.units.rotationsPerMinuteToRadiansPerSecond(
                self.kMaxSetpointValue
            ),
        )

        # Set setpoint and measurement of the bang-bang controller
        bangOutput = (
            self.bangBangControler.calculate(self.encoder.getRate(), setpoint) * 12.0
        )

        # Controls a motor with the output of the BangBang controller and a
        # feedforward. The feedforward is reduced slightly to avoid overspeeding
        # the shooter.
        self.flywheelMotor.setVoltage(
            bangOutput + 0.9 * self.feedforward.calculate(setpoint)
        )

    def simulationPeriodic(self) -> None:
        """Update our simulation. This should be run every robot loop in simulation."""
        # To update our simulation, we set motor voltage inputs, update the
        # simulation, and write the simulated velocities to our simulated encoder
        self.flywheelSim.setInputVoltage(
            self.flywheelMotor.get() * wpilib.RobotController.getInputVoltage()
        )
        self.flywheelSim.update(0.02)
        self.encoderSim.setRate(self.flywheelSim.getAngularVelocity())