Differential (Tank) Drivetrain

IMPORTANT

This page outlines how to use the differential drivetrain commands to control your robot in TeleOp.

INFO

For a differential drive, there are two types of drive systems. You can use the tank and arcade control schemes with a differential drive.

Arcade drive use a y-value input from the controller and a value from the turn stick. We know that when the turn stick is pushed left, the right side should move forward and the left side should move backwards. Therefore, since pushing the turn stick to the left returns a negative value, it should be added to the left speed and subtracted from the right speed.

Tank drive uses a y-value input from the left and right sticks. The sticks control their respective side of the robot.

Usage

First, you need to create your motors. Let's create variables for their names:

val frontLeftName = "front_left"
val frontRightName = "front_right"
val backLeftName = "back_left"
val backRightname = "back_right"

Next, we'll create variables for the motors and motor groups for each of the sides. If you only have one motor each side, you can skip creating the motor groups.

lateinit var frontLeftMotor: MotorEx
lateinit var frontRightMotor: MotorEx
lateinit var backLeftMotor: MotorEx
lateinit var backRightMotor: MotorEx

lateinit var leftMotors: MotorGroup
lateinit var rightMtoors: MotorGroup

Lastly, we'll create a variable for the command:

lateinit var driverControlled: Command

Now, in the onInit() function, we will initialize all our variables:

frontLeftMotor = MotorEx(frontLeftName)
backLeftMotor = MotorEx(backLeftName)
backRightMotor = MotorEx(backRightName)
frontRightMotor = MotorEx(frontRightName)

// Change your motor directions to suit your robot.
frontLeftMotor.direction = DcMotorSimple.Direction.REVERSE
backLeftMotor.direction = DcMotorSimple.Direction.REVERSE
frontRightMotor.direction = DcMotorSimple.Direction.FORWARD
backRightMotor.direction = DcMotorSimple.Direction.FORWARD

// Skip this if you are only using two motors.
leftMotors = MotorGroup(frontLeftMotor, backLeftMotor)
rightMotors = MotorGroup(frontRightMotor, backRightMotor)

Lastly, in onStartButtonPressed(), we will create and schedule our command.

TIP

If you are only using two motors, you can just pass your motors to the command instead of motor groups.

You can run it as a tank drive:

driverControlled = DifferentialTankDriverControlled(leftMotors, rightMotors, gamepadManager.gamepad1)
driverControlled()

Or as an arcade drive:

driverControlled = DifferentialArcadeDriverControlled(leftMotors, rightMotors, gamepadManager.gamepad1, false, imu)
driverControlled()

That's it! Now you are able to control your holonomic drivetrain using a gamepad.

NOTE

See the DifferentialTankDriverControlled and DifferentialArcadeDriverControlled references more information.