MecanumDrive.h

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// 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.
 
#pragma once
 
#include <memory>
#include <string>
 
#include <units/angle.h>
#include <wpi/sendable/Sendable.h>
#include <wpi/sendable/SendableHelper.h>
 
#include "frc/drive/RobotDriveBase.h"
#include "frc/geometry/Rotation2d.h"
 
namespace frc {
 
class MotorController;
 
/**
 * A class for driving Mecanum drive platforms.
 *
 * Mecanum drives are rectangular with one wheel on each corner. Each wheel has
 * rollers toed in 45 degrees toward the front or back. When looking at the
 * wheels from the top, the roller axles should form an X across the robot.
 *
 * Drive base diagram:
 * <pre>
 * \\_______/
 * \\ |   | /
 *   |   |
 * /_|___|_\\
 * /       \\
 * </pre>
 *
 * Each Drive() function provides different inverse kinematic relations for a
 * Mecanum drive robot.
 *
 * This library uses the NWU axes convention (North-West-Up as external
 * reference in the world frame). The positive X axis points ahead, the positive
 * Y axis points to the left, and the positive Z axis points up. Rotations
 * follow the right-hand rule, so counterclockwise rotation around the Z axis is
 * positive.
 *
 * Note: the axis conventions used in this class differ from DifferentialDrive.
 * This may change in a future year's WPILib release.
 *
 * Inputs smaller then 0.02 will be set to 0, and larger values will be scaled
 * so that the full range is still used. This deadband value can be changed
 * with SetDeadband().
 *
 * MotorSafety is enabled by default. The DriveCartesian or DrivePolar
 * methods should be called periodically to avoid Motor Safety timeouts.
 */
class MecanumDrive : public RobotDriveBase,
                     public wpi::Sendable,
                     public wpi::SendableHelper<MecanumDrive> {
 public:
  /**
   * Wheel speeds for a mecanum drive.
   *
   * Uses normalized voltage [-1.0..1.0].
   */
  struct WheelSpeeds {
    double frontLeft = 0.0;
    double frontRight = 0.0;
    double rearLeft = 0.0;
    double rearRight = 0.0;
  };
 
  /**
   * Construct a MecanumDrive.
   *
   * If a motor needs to be inverted, do so before passing it in.
   */
  MecanumDrive(MotorController& frontLeftMotor, MotorController& rearLeftMotor,
               MotorController& frontRightMotor,
               MotorController& rearRightMotor);
 
  ~MecanumDrive() override = default;
 
  MecanumDrive(MecanumDrive&&) = default;
  MecanumDrive& operator=(MecanumDrive&&) = default;
 
  /**
   * Drive method for Mecanum platform.
   *
   * Angles are measured counterclockwise from the positive X axis. The robot's
   * speed is independent from its angle or rotation rate.
   *
   * @param xSpeed    The robot's speed along the X axis [-1.0..1.0]. Forward is
   *                  positive.
   * @param ySpeed    The robot's speed along the Y axis [-1.0..1.0]. Left is
   *                  positive.
   * @param zRotation The robot's rotation rate around the Z axis [-1.0..1.0].
   *                  Counterclockwise is positive.
   * @param gyroAngle The gyro heading around the Z axis. Use this to implement
   *                  field-oriented controls.
   */
  void DriveCartesian(double xSpeed, double ySpeed, double zRotation,
                      Rotation2d gyroAngle = 0_rad);
 
  /**
   * Drive method for Mecanum platform.
   *
   * Angles are measured counterclockwise from the positive X axis. The robot's
   * speed is independent from its angle or rotation rate.
   *
   * @param magnitude The robot's speed at a given angle [-1.0..1.0]. Forward is
   *                  positive.
   * @param angle     The angle around the Z axis at which the robot drives.
   * @param zRotation The robot's rotation rate around the Z axis [-1.0..1.0].
   *                  Counterclockwise is positive.
   */
  void DrivePolar(double magnitude, Rotation2d angle, double zRotation);
 
  /**
   * Cartesian inverse kinematics for Mecanum platform.
   *
   * Angles are measured counterclockwise from the positive X axis. The robot's
   * speed is independent from its angle or rotation rate.
   *
   * @param xSpeed    The robot's speed along the X axis [-1.0..1.0]. Forward is
   *                  positive.
   * @param ySpeed    The robot's speed along the Y axis [-1.0..1.0]. Left is
   *                  positive.
   * @param zRotation The robot's rotation rate around the Z axis [-1.0..1.0].
   *                  Counterclockwise is positive.
   * @param gyroAngle The gyro heading around the Z axis. Use this to implement
   *                  field-oriented controls.
   * @return Wheel speeds [-1.0..1.0].
   */
  static WheelSpeeds DriveCartesianIK(double xSpeed, double ySpeed,
                                      double zRotation,
                                      Rotation2d gyroAngle = 0_rad);
 
  void StopMotor() override;
  std::string GetDescription() const override;
 
  void InitSendable(wpi::SendableBuilder& builder) override;
 
 private:
  MotorController* m_frontLeftMotor;
  MotorController* m_rearLeftMotor;
  MotorController* m_frontRightMotor;
  MotorController* m_rearRightMotor;
 
  bool reported = false;
};
 
}  // namespace frc