Project 1: A Production-Ready Driver Control Scheme

A great control scheme is invisible: the driver thinks "go there" and the robot goes there. Let's build one in WPILib command-based Java that an actual competition driver can use.

Start in RobotContainer with a CommandXboxController on port 0. WPILib gives you named factory methods for every button, so you bind declaratively instead of polling in a loop.

private final CommandXboxController driver = new CommandXboxController(0);
private final DriveSubsystem drive = new DriveSubsystem();

private void configureBindings() {
  // Default command: field-relative joystick drive every loop
  drive.setDefaultCommand(drive.run(() -> drive.driveFieldRelative(
      -driver.getLeftY(),   // forward (Y is inverted on Xbox sticks)
      -driver.getLeftX(),   // strafe
      -driver.getRightX()   // rotation
  )));

  // Reset field-relative heading to "away from driver station"
  driver.start().onTrue(drive.runOnce(drive::zeroHeading));

  // Hold left bumper for precision/slow mode
  driver.leftBumper().whileTrue(drive.run(() -> drive.driveFieldRelative(
      -driver.getLeftY() * 0.35,
      -driver.getLeftX() * 0.35,
      -driver.getRightX() * 0.35)));
}

Key design choices, each grounded in real practice:

• Invert the Y axes. Xbox sticks report +1 when pulled toward the driver, so forward needs a negative sign. Forgetting this is the single most common day-one bug.
• onTrue vs whileTrue. onTrue runs once on a rising edge (perfect for a gyro reset); whileTrue runs while held and cancels on release (perfect for slow mode). These are the two binding methods you'll use most.
• Slow mode by scaling, not a separate command tree. Multiplying inputs by 0.35 gives about one-third speed for lining up on the HUB or playing careful defense, without duplicating logic.

Apply a deadband so a drifting stick doesn't creep the robot. WPILib's MathUtil.applyDeadband(value, 0.1) is the idiomatic call; the DifferentialDrive class already applies 0.02 internally, but swerve code should apply your own (0.05–0.10 is typical).

double x = MathUtil.applyDeadband(-driver.getLeftX(), 0.1);

Finally, write down the physical mapping and tape it to the operator console: Left stick = translate, Right stick = rotate, Start = reset gyro, Left bumper = slow. Hand this card to a substitute driver and they should be able to drive a qualification match cold.

Test it on blocks first, then on the practice field. Drive a figure-eight around two cones; if the robot tracks where you point in field-relative mode regardless of which way the bumper faces, your gyro and inversions are correct.