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Basic mecanum driving with clear joystick, motor-power, and safety lessons.

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01MOTOR SETUP — WHY DIRECTIONS MATTER

The motors on opposite sides are mounted as mirror images. If all four received +1 without correction, one side would spin backward. Reversing the left motors in software makes +1 mean forward for every wheel. BRAKE means the motor actively holds still at zero power instead of coasting.

02INIT AND START

INIT means initialize: prepare the robot without allowing it to drive. waitForStart pauses here until the human presses START on the Driver Station. This safety boundary prevents joystick noise or unfinished setup from moving the robot early.

03JOYSTICK COORDINATES

Each joystick axis reports a decimal from -1 to +1. Left-stick X means side-to-side, and left-stick Y means up/down. Controllers report pushing upward as a negative Y number, so the program multiplies it by -1 to make pushing forward produce positive forward motion. Right-stick X becomes rotation.

04SLOW MODE

Normally speed is 1.0, meaning 100% of the calculated power. Holding the left bumper changes the scale to 0.35, or 35%. Multiplying every wheel by the same scale keeps the movement direction the same while making practice safer and more precise.

05WHY ADD ABSOLUTE VALUES?

06NORMALIZATION — SHRINK WITHOUT CHANGING SHAPE

Motor power must stay between -1 and +1. If the denominator is less than 1, we replace it with 1 so we never make small commands larger. Dividing all wheels by the same denominator shrinks oversized values equally, preserving the intended direction and rotation.

07MECANUM WHEEL MIXING

Mecanum rollers let the robot combine three motions: forward, sideways, and turning. Each wheel needs a different plus/minus combination. For example, adding sideways power to one diagonal and subtracting it from the other diagonal creates a strafe without rotating the robot.

08TELEMETRY MEANS DATA SENT BACK

Telemetry is information the Robot Controller sends to the Driver Station screen. It does not control the robot. These rows help us debug by showing the joystick requests and the power actually sent to each motor.

09FINAL SAFETY STOP

The loop ends when STOP is pressed or communication ends. Explicitly writing zero to all four motors is a final safety step so no earlier power value can remain active.

Safety: Read and predict before running. Raise the wheels for the first motor test, keep one person ready to press STOP, and never rely on camera code as the only safety system.

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This is what FTC Blocks generates for the Robot Controller. The visual Blocks above are the primary student source.

// IDENTIFIERS_USED=back_left_driveAsDcMotor,back_right_driveAsDcMotor,front_left_driveAsDcMotor,front_right_driveAsDcMotor,gamepad1

var forward2, strafe, turn, speed, denominator;

/**
 * BASIC MECANUM TELEOP
 *
 * Left stick: drive forward/backward and strafe left/right.
 * Right stick X: rotate.
 * Hold the left bumper: slow mode.
 *
 * The loop repeats until STOP is pressed.
 */
function runOpMode() {
  front_left_driveAsDcMotor.setDirection("REVERSE");
  back_left_driveAsDcMotor.setDirection("REVERSE");
  front_right_driveAsDcMotor.setDirection("FORWARD");
  back_right_driveAsDcMotor.setDirection("REVERSE");
  front_left_driveAsDcMotor.setZeroPowerBehavior("BRAKE");
  front_right_driveAsDcMotor.setZeroPowerBehavior("BRAKE");
  back_left_driveAsDcMotor.setZeroPowerBehavior("BRAKE");
  back_right_driveAsDcMotor.setZeroPowerBehavior("BRAKE");
  front_left_driveAsDcMotor.setMode("RUN_WITHOUT_ENCODER");
  front_right_driveAsDcMotor.setMode("RUN_WITHOUT_ENCODER");
  back_left_driveAsDcMotor.setMode("RUN_WITHOUT_ENCODER");
  back_right_driveAsDcMotor.setMode("RUN_WITHOUT_ENCODER");
  front_left_driveAsDcMotor.setPower(0);
  front_right_driveAsDcMotor.setPower(0);
  back_left_driveAsDcMotor.setPower(0);
  back_right_driveAsDcMotor.setPower(0);
  telemetry.addLine('READY - basic mecanum drive');
  telemetry.update();
  linearOpMode.waitForStart();
  while (linearOpMode.opModeIsActive()) {
    forward2 = -gamepad1.getLeftStickY();
    strafe = gamepad1.getLeftStickX();
    turn = gamepad1.getRightStickX();
    speed = 1;
    if (gamepad1.getLeftBumper()) {
      speed = 0.35;
    }
    denominator = Math.abs(forward2) + Math.abs(strafe) + Math.abs(turn);
    if (denominator < 1) {
      denominator = 1;
    }
    front_left_driveAsDcMotor.setPower(speed * ((forward2 + strafe + turn) / denominator));
    front_right_driveAsDcMotor.setPower(speed * (((forward2 - strafe) - turn) / denominator));
    back_left_driveAsDcMotor.setPower(speed * (((forward2 - strafe) + turn) / denominator));
    back_right_driveAsDcMotor.setPower(speed * (((forward2 + strafe) - turn) / denominator));
    telemetry.addNumericData('Forward command', forward2);
    telemetry.addNumericData('Strafe command', strafe);
    telemetry.addNumericData('Rotate command', turn);
    telemetry.addNumericData('Speed scale', speed);
    telemetry.addNumericData('FL motor power', front_left_driveAsDcMotor.getPower());
    telemetry.addNumericData('FR motor power', front_right_driveAsDcMotor.getPower());
    telemetry.addNumericData('BL motor power', back_left_driveAsDcMotor.getPower());
    telemetry.addNumericData('BR motor power', back_right_driveAsDcMotor.getPower());
    telemetryAddTextData('Face buttons', ['A:',gamepad1.getA(),' B:',gamepad1.getB(),' X:',gamepad1.getX(),' Y:',gamepad1.getY()].join(''));
    telemetryAddTextData('D-pad', ['U:',gamepad1.getDpadUp(),' D:',gamepad1.getDpadDown(),' L:',gamepad1.getDpadLeft(),' R:',gamepad1.getDpadRight()].join(''));
    telemetryAddTextData('Other buttons', ['LB:',gamepad1.getLeftBumper(),' RB:',gamepad1.getRightBumper(),' Start:',gamepad1.getStart(),' Back:',gamepad1.getBack()].join(''));
    telemetry.update();
  }
  front_left_driveAsDcMotor.setPower(0);
  front_right_driveAsDcMotor.setPower(0);
  back_left_driveAsDcMotor.setPower(0);
  back_right_driveAsDcMotor.setPower(0);
}