Add TrapezoidProfile external PID examples (#2131)

wpilibcExamples/src/main/cpp/examples/DriveDistanceOffboard/cpp/Robot.cpp

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+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2017-2019 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "Robot.h"
+
+#include <frc/smartdashboard/SmartDashboard.h>
+#include <frc2/command/CommandScheduler.h>
+
+void Robot::RobotInit() {}
+
+/**
+ * This function is called every robot packet, no matter the mode. Use
+ * this for items like diagnostics that you want to run during disabled,
+ * autonomous, teleoperated and test.
+ *
+ * <p> This runs after the mode specific periodic functions, but before
+ * LiveWindow and SmartDashboard integrated updating.
+ */
+void Robot::RobotPeriodic() { frc2::CommandScheduler::GetInstance().Run(); }
+
+/**
+ * This function is called once each time the robot enters Disabled mode. You
+ * can use it to reset any subsystem information you want to clear when the
+ * robot is disabled.
+ */
+void Robot::DisabledInit() {}
+
+void Robot::DisabledPeriodic() {}
+
+/**
+ * This autonomous runs the autonomous command selected by your {@link
+ * RobotContainer} class.
+ */
+void Robot::AutonomousInit() {
+  m_autonomousCommand = m_container.GetAutonomousCommand();
+
+  if (m_autonomousCommand != nullptr) {
+    m_autonomousCommand->Schedule();
+  }
+}
+
+void Robot::AutonomousPeriodic() {}
+
+void Robot::TeleopInit() {
+  // This makes sure that the autonomous stops running when
+  // teleop starts running. If you want the autonomous to
+  // continue until interrupted by another command, remove
+  // this line or comment it out.
+  if (m_autonomousCommand != nullptr) {
+    m_autonomousCommand->Cancel();
+    m_autonomousCommand = nullptr;
+  }
+}
+
+/**
+ * This function is called periodically during operator control.
+ */
+void Robot::TeleopPeriodic() {}
+
+/**
+ * This function is called periodically during test mode.
+ */
+void Robot::TestPeriodic() {}
+
+#ifndef RUNNING_FRC_TESTS
+int main() { return frc::StartRobot<Robot>(); }
+#endif

wpilibcExamples/src/main/cpp/examples/DriveDistanceOffboard/cpp/RobotContainer.cpp

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+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "RobotContainer.h"
+
+#include <frc/shuffleboard/Shuffleboard.h>
+#include <frc2/command/button/JoystickButton.h>
+
+#include "commands/DriveDistanceProfiled.h"
+
+RobotContainer::RobotContainer() {
+  // Initialize all of your commands and subsystems here
+
+  // Configure the button bindings
+  ConfigureButtonBindings();
+
+  // Set up default drive command
+  m_drive.SetDefaultCommand(frc2::RunCommand(
+      [this] {
+        m_drive.ArcadeDrive(
+            m_driverController.GetY(frc::GenericHID::kLeftHand),
+            m_driverController.GetX(frc::GenericHID::kRightHand));
+      },
+      {&m_drive}));
+}
+
+void RobotContainer::ConfigureButtonBindings() {
+  // Configure your button bindings here
+
+  // While holding the shoulder button, drive at half speed
+  frc2::JoystickButton(&m_driverController, 6)
+      .WhenPressed(&m_driveHalfSpeed)
+      .WhenReleased(&m_driveFullSpeed);
+
+  // Drive forward by 3 meters when the 'A' button is pressed, with a timeout of
+  // 10 seconds
+  frc2::JoystickButton(&m_driverController, 1)
+      .WhenPressed(DriveDistanceProfiled(3_m, &m_drive).WithTimeout(10_s));
+
+  // Do the same thing as above when the 'B' button is pressed, but defined
+  // inline
+  frc2::JoystickButton(&m_driverController, 2)
+      .WhenPressed(
+          frc2::TrapezoidProfileCommand<units::meters>(
+              frc::TrapezoidProfile<units::meters>(
+                  // Limit the max acceleration and velocity
+                  {DriveConstants::kMaxSpeed, DriveConstants::kMaxAcceleration},
+                  // End at desired position in meters; implicitly starts at 0
+                  {3_m, 0_mps}),
+              // Pipe the profile state to the drive
+              [this](auto setpointState) {
+                m_drive.SetDriveStates(setpointState, setpointState);
+              },
+              // Require the drive
+              {&m_drive})
+              .BeforeStarting([this]() { m_drive.ResetEncoders(); })
+              .WithTimeout(10_s));
+}
+
+frc2::Command* RobotContainer::GetAutonomousCommand() {
+  // Runs the chosen command in autonomous
+  return new frc2::InstantCommand([] {});
+}

wpilibcExamples/src/main/cpp/examples/DriveDistanceOffboard/cpp/commands/DriveDistanceProfiled.cpp

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+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "commands/DriveDistanceProfiled.h"
+
+#include "Constants.h"
+
+using namespace DriveConstants;
+
+DriveDistanceProfiled::DriveDistanceProfiled(units::meter_t distance,
+                                             DriveSubsystem* drive)
+    : CommandHelper(
+          frc::TrapezoidProfile<units::meters>(
+              // Limit the max acceleration and velocity
+              {kMaxSpeed, kMaxAcceleration},
+              // End at desired position in meters; implicitly starts at 0
+              {distance, 0_mps}),
+          // Pipe the profile state to the drive
+          [drive](auto setpointState) {
+            drive->SetDriveStates(setpointState, setpointState);
+          },
+          // Require the drive
+          {drive}) {
+  // Reset drive encoders since we're starting at 0
+  drive->ResetEncoders();
+}

wpilibcExamples/src/main/cpp/examples/DriveDistanceOffboard/cpp/subsystems/DriveSubsystem.cpp

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+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "subsystems/DriveSubsystem.h"
+
+using namespace DriveConstants;
+
+DriveSubsystem::DriveSubsystem()
+    : m_leftMaster{kLeftMotor1Port},
+      m_leftSlave{kLeftMotor2Port},
+      m_rightMaster{kRightMotor1Port},
+      m_rightSlave{kRightMotor2Port},
+      m_feedforward{ks, kv, ka} {
+  m_leftSlave.Follow(m_leftMaster);
+  m_rightSlave.Follow(m_rightMaster);
+
+  m_leftMaster.SetPID(kp, 0, 0);
+  m_rightMaster.SetPID(kp, 0, 0);
+}
+
+void DriveSubsystem::Periodic() {
+  // Implementation of subsystem periodic method goes here.
+}
+
+void DriveSubsystem::SetDriveStates(
+    frc::TrapezoidProfile<units::meters>::State left,
+    frc::TrapezoidProfile<units::meters>::State right) {
+  m_leftMaster.SetSetpoint(ExampleSmartMotorController::PIDMode::kPosition,
+                           left.position.to<double>(),
+                           m_feedforward.Calculate(left.velocity) / 12_V);
+  m_rightMaster.SetSetpoint(ExampleSmartMotorController::PIDMode::kPosition,
+                            right.position.to<double>(),
+                            m_feedforward.Calculate(right.velocity) / 12_V);
+}
+
+void DriveSubsystem::ArcadeDrive(double fwd, double rot) {
+  m_drive.ArcadeDrive(fwd, rot);
+}
+
+void DriveSubsystem::ResetEncoders() {
+  m_leftMaster.ResetEncoder();
+  m_rightMaster.ResetEncoder();
+}
+
+units::meter_t DriveSubsystem::GetLeftEncoderDistance() {
+  return units::meter_t(m_leftMaster.GetEncoderDistance());
+}
+
+units::meter_t DriveSubsystem::GetRightEncoderDistance() {
+  return units::meter_t(m_rightMaster.GetEncoderDistance());
+}
+
+void DriveSubsystem::SetMaxOutput(double maxOutput) {
+  m_drive.SetMaxOutput(maxOutput);
+}

wpilibcExamples/src/main/cpp/examples/DriveDistanceOffboard/include/Constants.h

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+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#pragma once
+
+#include <units/units.h>
+#include <wpi/math>
+
+/**
+ * The Constants header provides a convenient place for teams to hold robot-wide
+ * numerical or bool constants.  This should not be used for any other purpose.
+ *
+ * It is generally a good idea to place constants into subsystem- or
+ * command-specific namespaces within this header, which can then be used where
+ * they are needed.
+ */
+
+namespace DriveConstants {
+constexpr int kLeftMotor1Port = 0;
+constexpr int kLeftMotor2Port = 1;
+constexpr int kRightMotor1Port = 2;
+constexpr int kRightMotor2Port = 3;
+
+// These are example values only - DO NOT USE THESE FOR YOUR OWN ROBOT!
+// These characterization values MUST be determined either experimentally or
+// theoretically for *your* robot's drive. The RobotPy Characterization
+// Toolsuite provides a convenient tool for obtaining these values for your
+// robot.
+constexpr auto ks = 1_V;
+constexpr auto kv = 0.8_V * 1_s / 1_m;
+constexpr auto ka = 0.15_V * 1_s * 1_s / 1_m;
+
+constexpr double kp = 1;
+
+constexpr auto kMaxSpeed = 3_mps;
+constexpr auto kMaxAcceleration = 3_mps_sq;
+
+}  // namespace DriveConstants
+
+namespace OIConstants {
+constexpr int kDriverControllerPort = 1;
+}  // namespace OIConstants

wpilibcExamples/src/main/cpp/examples/DriveDistanceOffboard/include/ExampleSmartMotorController.h

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+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#pragma once
+
+#include <frc/SpeedController.h>
+
+/**
+ * A simplified stub class that simulates the API of a common "smart" motor
+ * controller.
+ *
+ * <p>Has no actual functionality.
+ */
+class ExampleSmartMotorController : public frc::SpeedController {
+ public:
+  enum PIDMode { kPosition, kVelocity, kMovementWitchcraft };
+
+  /**
+   * Creates a new ExampleSmartMotorController.
+   *
+   * @param port The port for the controller.
+   */
+  explicit ExampleSmartMotorController(int port) {}
+
+  /**
+   * Example method for setting the PID gains of the smart controller.
+   *
+   * @param kp The proportional gain.
+   * @param ki The integral gain.
+   * @param kd The derivative gain.
+   */
+  void SetPID(double kp, double ki, double kd) {}
+
+  /**
+   * Example method for setting the setpoint of the smart controller in PID
+   * mode.
+   *
+   * @param mode The mode of the PID controller.
+   * @param setpoint The controller setpoint.
+   * @param arbFeedforward An arbitrary feedforward output (from -1 to 1).
+   */
+  void SetSetpoint(PIDMode mode, double setpoint, double arbFeedforward) {}
+
+  /**
+   * Places this motor controller in follower mode.
+   *
+   * @param master The master to follow.
+   */
+  void Follow(ExampleSmartMotorController master) {}
+
+  /**
+   * Returns the encoder distance.
+   *
+   * @return The current encoder distance.
+   */
+  double GetEncoderDistance() { return 0; }
+
+  /**
+   * Returns the encoder rate.
+   *
+   * @return The current encoder rate.
+   */
+  double GetEncoderRate() { return 0; }
+
+  /**
+   * Resets the encoder to zero distance.
+   */
+  void ResetEncoder() {}
+
+  void Set(double speed) override {}
+
+  double Get() const override { return 0; }
+
+  void SetInverted(bool isInverted) override {}
+
+  bool GetInverted() const override { return false; }
+
+  void Disable() override {}
+
+  void StopMotor() override {}
+
+  void PIDWrite(double output) override {}
+};

wpilibcExamples/src/main/cpp/examples/DriveDistanceOffboard/include/Robot.h

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+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2017-2019 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#pragma once
+
+#include <frc/TimedRobot.h>
+#include <frc2/command/Command.h>
+
+#include "RobotContainer.h"
+
+class Robot : public frc::TimedRobot {
+ public:
+  void RobotInit() override;
+  void RobotPeriodic() override;
+  void DisabledInit() override;
+  void DisabledPeriodic() override;
+  void AutonomousInit() override;
+  void AutonomousPeriodic() override;
+  void TeleopInit() override;
+  void TeleopPeriodic() override;
+  void TestPeriodic() override;
+
+ private:
+  // Have it null by default so that if testing teleop it
+  // doesn't have undefined behavior and potentially crash.
+  frc2::Command* m_autonomousCommand = nullptr;
+
+  RobotContainer m_container;
+};

wpilibcExamples/src/main/cpp/examples/DriveDistanceOffboard/include/RobotContainer.h

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+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#pragma once
+
+#include <frc/XboxController.h>
+#include <frc/smartdashboard/SendableChooser.h>
+#include <frc2/command/Command.h>
+#include <frc2/command/InstantCommand.h>
+#include <frc2/command/ParallelRaceGroup.h>
+#include <frc2/command/RunCommand.h>
+#include <frc2/command/SequentialCommandGroup.h>
+#include <frc2/command/StartEndCommand.h>
+
+#include "Constants.h"
+#include "subsystems/DriveSubsystem.h"
+
+/**
+ * This class is where the bulk of the robot should be declared.  Since
+ * Command-based is a "declarative" paradigm, very little robot logic should
+ * actually be handled in the {@link Robot} periodic methods (other than the
+ * scheduler calls).  Instead, the structure of the robot (including subsystems,
+ * commands, and button mappings) should be declared here.
+ */
+class RobotContainer {
+ public:
+  RobotContainer();
+
+  frc2::Command* GetAutonomousCommand();
+
+ private:
+  // The driver's controller
+  frc::XboxController m_driverController{OIConstants::kDriverControllerPort};
+
+  // The robot's subsystems and commands are defined here...
+
+  // The robot's subsystems
+  DriveSubsystem m_drive;
+
+  frc2::InstantCommand m_driveHalfSpeed{[this] { m_drive.SetMaxOutput(0.5); },
+                                        {}};
+  frc2::InstantCommand m_driveFullSpeed{[this] { m_drive.SetMaxOutput(1); },
+                                        {}};
+
+  void ConfigureButtonBindings();
+};

wpilibcExamples/src/main/cpp/examples/DriveDistanceOffboard/include/commands/DriveDistanceProfiled.h

@@ -0,0 +1,20 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#pragma once
+
+#include <frc2/command/CommandHelper.h>
+#include <frc2/command/TrapezoidProfileCommand.h>
+
+#include "subsystems/DriveSubsystem.h"
+
+class DriveDistanceProfiled
+    : public frc2::CommandHelper<frc2::TrapezoidProfileCommand<units::meters>,
+                                 DriveDistanceProfiled> {
+ public:
+  DriveDistanceProfiled(units::meter_t distance, DriveSubsystem* drive);
+};

wpilibcExamples/src/main/cpp/examples/DriveDistanceOffboard/include/subsystems/DriveSubsystem.h

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+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#pragma once
+
+#include <frc/Encoder.h>
+#include <frc/controller/SimpleMotorFeedforward.h>
+#include <frc/drive/DifferentialDrive.h>
+#include <frc/trajectory/TrapezoidProfile.h>
+#include <frc2/command/SubsystemBase.h>
+#include <units/units.h>
+
+#include "Constants.h"
+#include "ExampleSmartMotorController.h"
+
+class DriveSubsystem : public frc2::SubsystemBase {
+ public:
+  DriveSubsystem();
+
+  /**
+   * Will be called periodically whenever the CommandScheduler runs.
+   */
+  void Periodic() override;
+
+  // Subsystem methods go here.
+
+  /**
+   * Attempts to follow the given drive states using offboard PID.
+   *
+   * @param left The left wheel state.
+   * @param right The right wheel state.
+   */
+  void SetDriveStates(frc::TrapezoidProfile<units::meters>::State left,
+                      frc::TrapezoidProfile<units::meters>::State right);
+
+  /**
+   * Drives the robot using arcade controls.
+   *
+   * @param fwd the commanded forward movement
+   * @param rot the commanded rotation
+   */
+  void ArcadeDrive(double fwd, double rot);
+
+  /**
+   * Resets the drive encoders to currently read a position of 0.
+   */
+  void ResetEncoders();
+
+  /**
+   * Gets the distance of the left encoder.
+   *
+   * @return the average of the TWO encoder readings
+   */
+  units::meter_t GetLeftEncoderDistance();
+
+  /**
+   * Gets the distance of the right encoder.
+   *
+   * @return the average of the TWO encoder readings
+   */
+  units::meter_t GetRightEncoderDistance();
+
+  /**
+   * Sets the max output of the drive.  Useful for scaling the drive to drive
+   * more slowly.
+   *
+   * @param maxOutput the maximum output to which the drive will be constrained
+   */
+  void SetMaxOutput(double maxOutput);
+
+ private:
+  // Components (e.g. motor controllers and sensors) should generally be
+  // declared private and exposed only through public methods.
+
+  // The motor controllers
+  ExampleSmartMotorController m_leftMaster;
+  ExampleSmartMotorController m_leftSlave;
+  ExampleSmartMotorController m_rightMaster;
+  ExampleSmartMotorController m_rightSlave;
+
+  // A feedforward component for the drive
+  frc::SimpleMotorFeedforward<units::meters> m_feedforward;
+
+  // The robot's drive
+  frc::DifferentialDrive m_drive{m_leftMaster, m_rightMaster};
+};