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Lesson 3.5: Challenge — Build Dynamic Power Logic with Multiple Variables

Technical Context​

A competitive robot rarely runs at a static speed. By combining multiple variables (inputs, multipliers, and offsets), you can create dynamic control systems. For instance, scaling joystick input by a "Battery Multiplier" variable ensures consistent robot performance even as the 12V battery voltage drops during a match.

How to Think Through Multi-Variable Power Logic​

This challenge requires manipulating different variable types in a single expression. When an int and a double are used in the same math operation, Java "promotes" the result to a double to maintain precision. You must be careful with assignment operators; using = updates the variable's value, while using *= or += allows you to modify the current value relative to its previous state.

Annotated Code​

@TeleOp(name="Dynamic_Control")
public class DynamicControl extends OpMode {

    DcMotor drive;

    // Multi-variable setup
    double baseSpeed       = 0.5;
    double boostMultiplier = 2.0;
    int    gearSetting     = 1;

    @Override
    public void init() {
        drive = hardwareMap.get(DcMotor.class, "motor");
    }

    @Override
    public void loop() {
        double finalPower;

        if (gamepad1.right_trigger > 0.5) {
            // Math combining double inputs and multipliers
            finalPower = baseSpeed * boostMultiplier;
        } else {
            finalPower = baseSpeed;
        }

        drive.setPower(finalPower);
        telemetry.addData("Gear", gearSetting);
        telemetry.addData("Output Power", finalPower);
    }
}

Fill-in-the-Blank Practice​

  1. The operator used to assign a new value to a variable is __________.
  2. If you multiply an int by a double, the resulting datatype will be a/an __________.
  3. To perform math and update a variable in one step (e.g., adding 5 to the current value), you use the __________ operator.
Show answers
  1. =
  2. double (Java promotes the result to the wider type)
  3. +=

Template Challenge​

Robot Scenario: Create a "Precision Mode." If the driver holds the left bumper, the motor power should be exactly half of the joystick input. Use variables for input, scaleFactor, and finalPower.

Unit 3 simulator
Tracks `String`, `double`, `boolean`, and `int` variables as you edit.
Supports telemetry, `gamepad1`, simple `if` blocks, and basic `setPower()` math.
Does not simulate full hardware behavior or complex Java control flow.
Show answer
@Override
public void loop() {
    double input = -gamepad1.left_stick_y;

    double finalPower;

    if (gamepad1.left_bumper) {
        finalPower = input * scaleFactor;
    } else {
        finalPower = input;
    }

    motor.setPower(finalPower);
}

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