Arming and disarming sequence in Drone Programming - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of arming sequence with safety check

What is the output of this drone arming code snippet when the safety switch is off?

Drone Programming

safety_switch = False
armed = False
if safety_switch:
    armed = True
print('Armed' if armed else 'Disarmed')

A Disarmed

B Armed

C Error: safety_switch undefined

D None

💡 Hint

Check the condition that sets the armed state.

The safety switch is off (False), so the condition to arm the drone is not met. The drone remains disarmed.

🧠 Conceptual

intermediate

Understanding disarming conditions

Which condition below correctly disarms the drone in a typical sequence?

A If battery level is below threshold, disarm immediately.

B If throttle stick is at maximum, disarm immediately.

C If GPS signal is strong, disarm immediately.

D If safety switch is on, disarm immediately.

💡 Hint

Think about what safety-critical conditions require disarming.

Low battery is a critical safety condition that requires immediate disarming to prevent crash or damage.

🔧 Debug

advanced

Identify the error in the arming code

What error does this code produce when run? armed = False safety_switch = True if safety_switch = True: armed = True print('Armed' if armed else 'Disarmed')

A NameError: name 'safety_switch' is not defined

B SyntaxError: invalid syntax

C TypeError: unsupported operand type(s)

D No error, prints 'Armed'

💡 Hint

Check the if statement syntax carefully.

The if statement uses '=' instead of '==', causing a syntax error.

🚀 Application

advanced

Number of steps in a safe arming sequence

How many distinct steps are typically required to safely arm a drone?

A 1 step: Flip safety switch

B 3 steps: Confirm safety switch, throttle low, and GPS lock

C 4 steps: Confirm safety switch, throttle low, GPS lock, and battery check

D 2 steps: Confirm safety switch and throttle low

💡 Hint

Consider all safety checks before arming.

A safe arming sequence includes multiple checks: safety switch, throttle position, GPS lock, and battery level.

❓ Predict Output

expert

Output of complex arming/disarming logic

What is the output of this code? status = 'disarmed' safety_switch = True throttle = 0 battery = 15 GPS_lock = True if safety_switch and throttle == 0 and battery > 20 and GPS_lock: status = 'armed' elif battery <= 20: status = 'disarmed due to low battery' else: status = 'disarmed' print(status)

Drone Programming

status = 'disarmed'
safety_switch = True
throttle = 0
battery = 15
GPS_lock = True

if safety_switch and throttle == 0 and battery > 20 and GPS_lock:
    status = 'armed'
elif battery <= 20:
    status = 'disarmed due to low battery'
else:
    status = 'disarmed'

print(status)

A Error: battery variable undefined

B armed

C disarmed

D disarmed due to low battery

💡 Hint

Check the battery condition and order of conditions.

Battery is 15 which is <= 20, so the elif condition triggers and sets status to 'disarmed due to low battery'.

Practice

1. What does arming a drone do in the flight sequence?

easy

A. Prepares the drone's motors to start spinning for flight

B. Stops the drone's motors immediately

C. Turns off the drone's power completely

D. Calibrates the drone's sensors automatically

Solution

1. Step 1: Understand the meaning of arming

   Arming means getting the drone ready to fly by enabling its motors to spin.

2. Step 2: Differentiate arming from disarming

   Disarming stops the motors, so arming must be the opposite: preparing motors to start.

3. Final Answer:

   Prepares the drone's motors to start spinning for flight -> Option A

4. Quick Check:

   Arming = prepare motors [OK]

Hint: Arming means motors ready to spin, not stop [OK]

Common Mistakes:

• Confusing arming with disarming
• Thinking arming turns off power
• Assuming arming calibrates sensors

2. Which of the following is the correct syntax to arm a drone using a function call in drone programming?

easy

A. armDrone{}

B. armDrone()

C. arm drone()

D. arm_drone[]

Solution

1. Step 1: Identify correct function call syntax

   Function calls use the format functionName() with parentheses and no spaces.

2. Step 2: Check each option

   armDrone() uses correct syntax: armDrone() with parentheses and no spaces.

3. Final Answer:

   armDrone() -> Option B

4. Quick Check:

   Function call = name() [OK]

Hint: Functions always use parentheses () to call [OK]

Common Mistakes:

• Using brackets [] or braces {} instead of parentheses
• Adding spaces inside function name
• Missing parentheses in function call

3. Given the code snippet:

drone_state = {'armed': False}

def arm():
    if not drone_state['armed']:
        drone_state['armed'] = True
        return 'Drone armed'
    else:
        return 'Drone already armed'

print(arm())
print(arm())

What is the output?

medium

A. Drone already armed\nDrone armed

B. Drone armed\nDrone armed

C. Drone armed\nDrone already armed

D. Error: KeyError

Solution

1. Step 1: Check initial drone state

   Initially, drone_state['armed'] is False, so first call to arm() sets it to True and returns 'Drone armed'.

2. Step 2: Analyze second call to arm()

   Now drone_state['armed'] is True, so second call returns 'Drone already armed'.

3. Final Answer:

   Drone armed\nDrone already armed -> Option C

4. Quick Check:

   First arm sets True, second arm detects already armed [OK]

Hint: First call arms, second call detects armed state [OK]

Common Mistakes:

• Assuming both calls arm the drone again
• Confusing the boolean check logic
• Expecting a KeyError due to dictionary access

4. The following code is intended to disarm the drone, but it causes an error:

drone_state = {'armed': True}

def disarm():
    if drone_state['armed'] = True:
        drone_state['armed'] = False
        return 'Drone disarmed'
    else:
        return 'Drone already disarmed'

print(disarm())

What is the error and how to fix it?

medium

A. KeyError: 'armed' key missing in drone_state

B. IndentationError: Incorrect indentation in function

C. TypeError: Cannot assign boolean to dictionary key

D. SyntaxError: Use '==' for comparison instead of '='

Solution

1. Step 1: Identify the error in the if condition

   The code uses '=' which is assignment, not comparison. This causes a SyntaxError.

2. Step 2: Correct the comparison operator

   Replace '=' with '==' to compare drone_state['armed'] to True.

3. Final Answer:

   SyntaxError: Use '==' for comparison instead of '=' -> Option D

4. Quick Check:

   Comparison needs '==' not '=' [OK]

Hint: Use '==' to compare values, '=' to assign [OK]

Common Mistakes:

• Using '=' instead of '==' in conditions
• Assuming dictionary key is missing
• Confusing indentation errors with syntax errors

5. You want to write a function toggle_arm() that arms the drone if disarmed, and disarms if armed. Given drone_state = {'armed': False}, which code correctly implements this behavior?

hard

A. def toggle_arm():
drone_state['armed'] = not drone_state['armed']
return 'Drone armed' if drone_state['armed'] else 'Drone disarmed'

B. def toggle_arm():
if drone_state['armed'] == False:
drone_state['armed'] = False
return 'Drone disarmed'
else:
drone_state['armed'] = True
return 'Drone armed'

C. def toggle_arm():
if not drone_state['armed']:
drone_state['armed'] = False
return 'Drone disarmed'
else:
drone_state['armed'] = True
return 'Drone armed'

D. def toggle_arm():
drone_state['armed'] = True
return 'Drone armed'
drone_state['armed'] = False
return 'Drone disarmed'

Solution

1. Step 1: Understand toggle logic

   Toggle means switch state: if armed, disarm; if disarmed, arm.

2. Step 2: Check each option's logic

   def toggle_arm(): drone_state['armed'] = not drone_state['armed'] return 'Drone armed' if drone_state['armed'] else 'Drone disarmed' uses 'not' to flip boolean and returns correct message based on new state.

3. Final Answer:

   def toggle_arm(): drone_state['armed'] = not drone_state['armed'] return 'Drone armed' if drone_state['armed'] else 'Drone disarmed' -> Option A

4. Quick Check:

   Toggle by flipping boolean with 'not' [OK]

Hint: Use 'not' to flip armed state quickly [OK]

Common Mistakes:

• Not flipping the state correctly
• Returning wrong message after toggle
• Code after return statement ignored