Package edu.wpi.first.wpilibj.drive

Class MecanumDrive

java.lang.Object
edu.wpi.first.wpilibj.MotorSafety
edu.wpi.first.wpilibj.drive.RobotDriveBase
edu.wpi.first.wpilibj.drive.MecanumDrive
All Implemented Interfaces:
Sendable, AutoCloseable
public class MecanumDrive
extends RobotDriveBase
implements Sendable, AutoCloseable
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. Each drive() function provides different inverse kinematic relations for a Mecanum drive robot.

Drive base diagram: 

 \\_______/
 \\ |   | /
   |   |
 /_|___|_\\
 /       \\

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 RobotDriveBase.setDeadband(double).

MotorSafety is enabled by default. The driveCartesian or drivePolar methods should be called periodically to avoid Motor Safety timeouts.

  • Constructor Details

    • MecanumDrive

      public MecanumDrive​(MotorController frontLeftMotor, MotorController rearLeftMotor, MotorController frontRightMotor, MotorController rearRightMotor)
      Construct a MecanumDrive.

      If a motor needs to be inverted, do so before passing it in.

      Parameters:
      frontLeftMotor - The motor on the front-left corner.
      rearLeftMotor - The motor on the rear-left corner.
      frontRightMotor - The motor on the front-right corner.
      rearRightMotor - The motor on the rear-right corner.

  • Method Details

    • close

      public void close()
      Specified by:
      close in interface AutoCloseable

    • driveCartesian

      public void driveCartesian​(double xSpeed, double ySpeed, double zRotation)
      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.

      Parameters:
      xSpeed - The robot's speed along the X axis [-1.0..1.0]. Forward is positive.
      ySpeed - The robot's speed along the Y axis [-1.0..1.0]. Left is positive.
      zRotation - The robot's rotation rate around the Z axis [-1.0..1.0]. Counterclockwise is positive.

    • driveCartesian

      public void driveCartesian​(double xSpeed, double ySpeed, double zRotation, Rotation2d gyroAngle)
      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.

      Parameters:
      xSpeed - The robot's speed along the Y axis [-1.0..1.0]. Forward is positive.
      ySpeed - The robot's speed along the X axis [-1.0..1.0]. Left is positive.
      zRotation - The robot's rotation rate around the Z axis [-1.0..1.0]. Counterclockwise is positive.
      gyroAngle - The gyro heading around the Z axis. Use this to implement field-oriented controls.

    • drivePolar

      public void drivePolar​(double magnitude, Rotation2d angle, double zRotation)
      Drive method for Mecanum platform.

      Angles are measured counterclockwise from straight ahead. The speed at which the robot drives (translation) is independent from its angle or rotation rate.

      Parameters:
      magnitude - The robot's speed at a given angle [-1.0..1.0]. Forward is positive.
      angle - The gyro heading around the Z axis at which the robot drives.
      zRotation - The robot's rotation rate around the Z axis [-1.0..1.0]. Counterclockwise is positive.

    • driveCartesianIK

      public static MecanumDrive.WheelSpeeds driveCartesianIK​(double xSpeed, double ySpeed, 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.

      Parameters:
      xSpeed - The robot's speed along the X axis [-1.0..1.0]. Forward is positive.
      ySpeed - The robot's speed along the Y axis [-1.0..1.0]. Left is positive.
      zRotation - The robot's rotation rate around the Z axis [-1.0..1.0]. Counterclockwise is positive.
      Returns:
      Wheel speeds [-1.0..1.0].

    • driveCartesianIK

      public static MecanumDrive.WheelSpeeds driveCartesianIK​(double xSpeed, double ySpeed, double zRotation, Rotation2d gyroAngle)
      Cartesian inverse kinematics for Mecanum platform.

      Angles are measured clockwise from the positive X axis. The robot's speed is independent from its angle or rotation rate.

      Parameters:
      xSpeed - The robot's speed along the X axis [-1.0..1.0]. Forward is positive.
      ySpeed - The robot's speed along the Y axis [-1.0..1.0]. Left is positive.
      zRotation - The robot's rotation rate around the Z axis [-1.0..1.0]. Counterclockwise is positive.
      gyroAngle - The gyro heading around the Z axis. Use this to implement field-oriented controls.
      Returns:
      Wheel speeds [-1.0..1.0].

    • stopMotor

      public void stopMotor()
      Specified by:
      stopMotor in class RobotDriveBase

    • getDescription

      public String getDescription()
      Specified by:
      getDescription in class RobotDriveBase

    • initSendable

      public void initSendable​(SendableBuilder builder)
      Description copied from interface: Sendable
      Initializes this Sendable object.
      Specified by:
      initSendable in interface Sendable
      Parameters:
      builder - sendable builder