Joystick mapping

Gamepad input

A gamepad stick gives a number between -1 and 1. Near the middle it is close to 0. On a typical FTC gamepad, pushing the left stick up makes left_stick_y negative, so code often uses -gamepad1.left_stick_y to make forward positive.

The Driver Station labels connected gamepads as gamepad1 and gamepad2. Check which driver holds each controller before assigning a mechanism.

Tank drive

Tank drive uses one stick for the left side and one for the right side. Configure the motors as left_drive and right_drive before running this example. Lift the drive wheels off the ground for the first test.

package org.firstinspires.ftc.teamcode;

import com.qualcomm.robotcore.eventloop.opmode.LinearOpMode;
import com.qualcomm.robotcore.eventloop.opmode.TeleOp;
import com.qualcomm.robotcore.hardware.DcMotor;

@TeleOp(name = "Tank Drive")
public class TankDrive extends LinearOpMode {
    @Override
    public void runOpMode() {
        DcMotor left = hardwareMap.get(DcMotor.class, "left_drive");
        DcMotor right = hardwareMap.get(DcMotor.class, "right_drive");

        waitForStart();
        while (opModeIsActive()) {
            double leftPower = -gamepad1.left_stick_y * 0.25;
            double rightPower = -gamepad1.right_stick_y * 0.25;
            left.setPower(leftPower);
            right.setPower(rightPower);
        }
        left.setPower(0);
        right.setPower(0);
    }
}

package org.firstinspires.ftc.teamcode

import com.qualcomm.robotcore.eventloop.opmode.LinearOpMode
import com.qualcomm.robotcore.eventloop.opmode.TeleOp
import com.qualcomm.robotcore.hardware.DcMotor

@TeleOp(name = "Tank Drive")
class TankDrive : LinearOpMode() {
    override fun runOpMode() {
        val left = hardwareMap.get(DcMotor::class.java, "left_drive")
        val right = hardwareMap.get(DcMotor::class.java, "right_drive")

        waitForStart()
        while (opModeIsActive()) {
            val leftPower = -gamepad1.left_stick_y.toDouble() * 0.25
            val rightPower = -gamepad1.right_stick_y.toDouble() * 0.25
            left.power = leftPower
            right.power = rightPower
        }
        left.power = 0.0
        right.power = 0.0
    }
}

The 0.25 factor limits speed while you check motor direction. With both sticks forward, both wheels should move the robot forward. If one wheel turns backward, correct that motor's direction in hardware setup or code before raising the speed. Do not assume that the right motor must always be reversed; mounting varies.

Button input

A button is either pressed or not pressed. Inside the same loop, a simple claw action could look like this after you have mapped and checked a servo named claw:

if (gamepad1.a) {
    claw.setPosition(CLOSED_POSITION);
} else if (gamepad1.b) {
    claw.setPosition(OPEN_POSITION);
}

CLOSED_POSITION and OPEN_POSITION are values your team must measure for its own claw, between 0.0 and 1.0. This fragment illustrates the button logic; it is not a complete OpMode.

Control tuning

• Dead zone: If a motor creeps while a stick is centered, treat a small input such as abs(value) < 0.05 as zero. Measure the drift on your gamepad before choosing the cutoff.
• Speed limit: Keep the 0.25 multiplier for initial tests, then raise it gradually if the robot is controllable.
• Telemetry: Show stick input and motor power during debugging so you can see whether a problem begins at the gamepad or motor.

Four-wheel mecanum and X-drive robots need a separate wheel-mixing calculation and careful checks of wheel order and direction. Once tank drive makes sense, check the geometry of your actual drivetrain. Do not paste a wheel formula for a different layout into your robot.

For an X-roller mecanum drivetrain, continue with Field-centric mecanum drive. It starts with direction checks, then adds an IMU heading so a stick direction stays aligned with the field as the robot turns.

Practice

Push only the left stick, then only the right stick. Predict which wheel will move before each test. When both sticks move together, explain why the robot goes forward or turns.