Add holonomic follower examples (#2052)

wpilibcExamples/src/main/cpp/examples/MecanumControllerCommand/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.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include <frc/geometry/Translation2d.h>
+#include <frc/kinematics/MecanumDriveKinematics.h>
+#include <frc/trajectory/TrapezoidProfile.h>
+#include <units/units.h>
+#include <wpi/math>
+
+#pragma once
+
+/**
+ * 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 kFrontLeftMotorPort = 0;
+constexpr int kRearLeftMotorPort = 1;
+constexpr int kFrontRightMotorPort = 2;
+constexpr int kRearRightMotorPort = 3;
+
+constexpr int kFrontLeftEncoderPorts[]{0, 1};
+constexpr int kRearLeftEncoderPorts[]{2, 3};
+constexpr int kFrontRightEncoderPorts[]{4, 5};
+constexpr int kRearRightEncoderPorts[]{5, 6};
+
+constexpr bool kFrontLeftEncoderReversed = false;
+constexpr bool kRearLeftEncoderReversed = true;
+constexpr bool kFrontRightEncoderReversed = false;
+constexpr bool kRearRightEncoderReversed = true;
+
+constexpr auto kTrackWidth =
+    0.5_m;  // Distance between centers of right and left wheels on robot
+constexpr auto kWheelBase =
+    0.7_m;  // Distance between centers of front and back wheels on robot
+extern const frc::MecanumDriveKinematics kDriveKinematics;
+
+constexpr int kEncoderCPR = 1024;
+constexpr double kWheelDiameterMeters = .15;
+constexpr double kEncoderDistancePerPulse =
+    // Assumes the encoders are directly mounted on the wheel shafts
+    (kWheelDiameterMeters * wpi::math::pi) / static_cast<double>(kEncoderCPR);
+
+constexpr bool kGyroReversed = false;
+
+// 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 * 1_V * 1_s / 1_m;
+constexpr auto ka = 0.15 * 1_V * 1_s * 1_s / 1_m;
+
+// Example value only - as above, this must be tuned for your drive!
+constexpr double kPFrontLeftVel = 0.5;
+constexpr double kPRearLeftVel = 0.5;
+constexpr double kPFrontRightVel = 0.5;
+constexpr double kPRearRightVel = 0.5;
+}  // namespace DriveConstants
+
+namespace AutoConstants {
+using radians_per_second_squared_t =
+    units::compound_unit<units::radians,
+                         units::inverse<units::squared<units::second>>>;
+
+constexpr auto kMaxSpeed = units::meters_per_second_t(3);
+constexpr auto kMaxAcceleration = units::meters_per_second_squared_t(3);
+constexpr auto kMaxAngularSpeed = units::radians_per_second_t(3);
+constexpr auto kMaxAngularAcceleration =
+    units::unit_t<radians_per_second_squared_t>(3);
+
+constexpr double kPXController = 0.5;
+constexpr double kPYController = 0.5;
+constexpr double kPThetaController = 0.5;
+
+constexpr frc::TrapezoidProfile<units::radians>::Constraints
+    kThetaControllerConstraints{kMaxAngularSpeed, kMaxAngularAcceleration};
+
+}  // namespace AutoConstants
+
+namespace OIConstants {
+constexpr int kDriverControllerPort = 1;
+}  // namespace OIConstants

wpilibcExamples/src/main/cpp/examples/MecanumControllerCommand/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/MecanumControllerCommand/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/controller/PIDController.h>
+#include <frc/controller/ProfiledPIDController.h>
+#include <frc/smartdashboard/SendableChooser.h>
+#include <frc2/command/Command.h>
+#include <frc2/command/InstantCommand.h>
+#include <frc2/command/PIDCommand.h>
+#include <frc2/command/ParallelRaceGroup.h>
+#include <frc2/command/RunCommand.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(.5); },
+                                        {}};
+  frc2::InstantCommand m_driveFullSpeed{[this] { m_drive.SetMaxOutput(1); },
+                                        {}};
+
+  // The chooser for the autonomous routines
+  frc::SendableChooser<frc2::Command*> m_chooser;
+
+  void ConfigureButtonBindings();
+};

wpilibcExamples/src/main/cpp/examples/MecanumControllerCommand/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/ADXRS450_Gyro.h>
+#include <frc/Encoder.h>
+#include <frc/PWMVictorSPX.h>
+#include <frc/drive/MecanumDrive.h>
+#include <frc/geometry/Pose2d.h>
+#include <frc/geometry/Rotation2d.h>
+#include <frc/interfaces/Gyro.h>
+#include <frc/kinematics/MecanumDriveOdometry.h>
+#include <frc/kinematics/MecanumDriveWheelSpeeds.h>
+#include <frc2/command/SubsystemBase.h>
+
+#include "Constants.h"
+
+class DriveSubsystem : public frc2::SubsystemBase {
+ public:
+  DriveSubsystem();
+
+  /**
+   * Will be called periodically whenever the CommandScheduler runs.
+   */
+  void Periodic() override;
+
+  // Subsystem methods go here.
+
+  /**
+   * Drives the robot at given x, y and theta speeds. Speeds range from [-1, 1]
+   * and the linear speeds have no effect on the angular speed.
+   *
+   * @param xSpeed        Speed of the robot in the x direction
+   *                      (forward/backwards).
+   * @param ySpeed        Speed of the robot in the y direction (sideways).
+   * @param rot           Angular rate of the robot.
+   * @param fieldRelative Whether the provided x and y speeds are relative to
+   *                      the field.
+   */
+  void Drive(double xSpeed, double ySpeed, double rot, bool feildRelative);
+
+  /**
+   * Resets the drive encoders to currently read a position of 0.
+   */
+  void ResetEncoders();
+
+  /**
+   * Gets the front left drive encoder.
+   *
+   * @return the front left drive encoder
+   */
+  frc::Encoder& GetFrontLeftEncoder();
+
+  /**
+   * Gets the rear left drive encoder.
+   *
+   * @return the rear left drive encoder
+   */
+  frc::Encoder& GetRearLeftEncoder();
+
+  /**
+   * Gets the front right drive encoder.
+   *
+   * @return the front right drive encoder
+   */
+  frc::Encoder& GetFrontRightEncoder();
+
+  /**
+   * Gets the rear right drive encoder.
+   *
+   * @return the rear right drive encoder
+   */
+  frc::Encoder& GetRearRightEncoder();
+
+  /**
+   * Gets the wheel speeds.
+   *
+   * @return the current wheel speeds.
+   */
+  frc::MecanumDriveWheelSpeeds getCurrentWheelSpeeds();
+
+  /**
+   * Sets the drive SpeedControllers to a desired voltage.
+   */
+  void SetSpeedControllersVolts(units::volt_t frontLeftPower,
+                                units::volt_t rearLeftPower,
+                                units::volt_t frontRightPower,
+                                units::volt_t rearRightPower);
+
+  /**
+   * 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);
+
+  /**
+   * Returns the heading of the robot.
+   *
+   * @return the robot's heading in degrees, from 180 to 180
+   */
+  double GetHeading();
+
+  /**
+   * Zeroes the heading of the robot.
+   */
+  void ZeroHeading();
+
+  /**
+   * Returns the turn rate of the robot.
+   *
+   * @return The turn rate of the robot, in degrees per second
+   */
+  double GetTurnRate();
+
+  /**
+   * Returns the currently-estimated pose of the robot.
+   *
+   * @return The pose.
+   */
+  frc::Pose2d GetPose();
+
+  /**
+   * Resets the odometry to the specified pose.
+   *
+   * @param pose The pose to which to set the odometry.
+   */
+  void ResetOdometry(frc::Pose2d pose);
+
+ private:
+  // Components (e.g. motor controllers and sensors) should generally be
+  // declared private and exposed only through public methods.
+
+  // The motor controllers
+  frc::PWMVictorSPX m_frontLeft;
+  frc::PWMVictorSPX m_rearLeft;
+  frc::PWMVictorSPX m_frontRight;
+  frc::PWMVictorSPX m_rearRight;
+
+  // The robot's drive
+  frc::MecanumDrive m_drive{m_frontLeft, m_rearLeft, m_frontRight, m_rearRight};
+
+  // The front-left-side drive encoder
+  frc::Encoder m_frontLeftEncoder;
+
+  // The rear-left-side drive encoder
+  frc::Encoder m_rearLeftEncoder;
+
+  // The front-right--side drive encoder
+  frc::Encoder m_frontRightEncoder;
+
+  // The rear-right-side drive encoder
+  frc::Encoder m_rearRightEncoder;
+
+  // The gyro sensor
+  frc::ADXRS450_Gyro m_gyro;
+
+  // Odometry class for tracking robot pose
+  frc::MecanumDriveOdometry m_odometry;
+};