Unit 5 Mastery Quiz: Logic & Decisions

I. Conceptual Questions

1. Mutual Exclusion: Why is it considered an engineering failure to use two independent if statements (e.g., if(gamepad1.a) and if(gamepad1.b)) to control a single motor's power instead of an else if chain?

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Independent statements allow both conditions to be true simultaneously. If both buttons are pressed, the Control Hub receives two conflicting setPower() commands in the same loop cycle, causing high-frequency voltage jitter and mechanical strain on the motor gears.

2. Threshold Resilience: Why should you use comparison operators (like >= or <=) instead of the equality operator (==) when checking sensor values like encoder ticks or IMU heading?

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Hardware sensors update at high speeds with high precision. Because the robot might move multiple ticks or degrees between loop cycles, it is unlikely to hit an exact integer value. Using a threshold ensures the logic triggers once the robot enters the target zone, rather than waiting for an exact match that may never occur.

3. Logical Combinations: What is the technical advantage of using a Logical AND (&&) operator over nested if statements when creating a hardware safety gate?

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Logical operators improve code readability and "self-documentation." A single if (isArmUp && isClawClosed) clearly defines the exact hardware state required for execution in one line, whereas nested if statements require reading two separate blocks to understand the same condition.

4. State Recovery: Why is a final else block critical when mapping gamepad buttons to motor power inside the loop() method?

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Without the catch-all else block, once a motor is given power by an if statement, it will continue to run at that voltage even after the button is released. The else block ensures the hardware returns to a zero-power state every cycle that no button is held.

5. Control Flow Logic: Why would an engineer use a switch statement with an enum instead of a long if/else if chain for an autonomous state machine?

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Using an enum allows the compiler to catch typos that would be missed with String-based logic. It also makes the code more readable and easier to expand — adding a new autonomous step is as simple as adding a new enum value and a corresponding case block.

II. Debug the Code

The following code is intended to stop a motor if a Distance Sensor sees a wall closer than 10 cm, otherwise it runs at a speed set by the trigger. Identify and fix the 2 errors.

@Override
public void loop() {
    double dist  = sensor.getDistance(DistanceUnit.CM);
    double power = gamepad1.right_trigger;

    if (dist < 10.0) {
        motor.setPower(0.0)
    }
    if (power > 0.1) {
        motor.setPower(power);
    }
}

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Error 1 — Syntax Error: The statement motor.setPower(0.0) inside the first if block is missing a semicolon (;). Java requires semicolons to terminate every command.

motor.setPower(0.0); // ← semicolon added

Error 2 — Logic Error: The programmer used two independent if blocks instead of an else if or else structure. If the robot is closer than 10 cm and the driver is still holding the trigger, the motor will be told to stop and then immediately told to move in the same loop cycle — the trigger logic overrides the safety sensor.

if (dist < 10.0) {
    motor.setPower(0.0);
} else if (power > 0.1) {
    motor.setPower(power);
} else {
    motor.setPower(0.0);
}

Ready to move on?

I. Conceptual Questions​

II. Debug the Code​

I. Conceptual Questions

II. Debug the Code