Command acknowledgment handling in Drone Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to send a command and wait for acknowledgment.

Drone Programming

send_command([1])
wait_for_ack()

Drag options to blanks, or click blank then click option'

ALAND

BTAKE_OFF

CMOVE_FORWARD

DHOVER

Attempts:

3 left

💡 Hint

Common Mistakes

Using a movement command instead of a takeoff command.

Not sending any command before waiting for acknowledgment.

The send_command function requires a command like TAKE_OFF to initiate the drone's takeoff and then waits for acknowledgment.

2fill in blank

medium

Complete the code to check if the acknowledgment status is successful.

Drone Programming

if ack_status == [1]:
    print('Command acknowledged')

Drag options to blanks, or click blank then click option'

ASUCCESS

BERROR

CTIMEOUT

DPENDING

Attempts:

3 left

💡 Hint

Common Mistakes

Checking for ERROR instead of SUCCESS.

Using PENDING which means acknowledgment is not yet received.

The acknowledgment status SUCCESS means the command was accepted by the drone.

3fill in blank

hard

Fix the error in the acknowledgment timeout handling code.

Drone Programming

if ack_received is not [1]:
    retry_command()

Drag options to blanks, or click blank then click option'

ATrue

BNone

CFalse

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Checking if ack_received is not False which is the opposite logic.

Using None or 0 which are not boolean values here.

The code checks if acknowledgment was not received (ack_received is not True) to retry the command.

4fill in blank

hard

Fill both blanks to create a dictionary of commands with their acknowledgment status.

Drone Programming

ack_dict = {cmd: [1] for cmd in commands if ack_status[cmd] [2] 'SUCCESS'}

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Aack_status[cmd]

B!=

C==

Dcmd

Attempts:

3 left

💡 Hint

Common Mistakes

Using the command name as the value instead of the acknowledgment status.

Using the wrong comparison operator like !=.

The dictionary comprehension maps each command to its acknowledgment status only if the status equals 'SUCCESS'.

5fill in blank

hard

Fill all three blanks to filter commands and create a dictionary with uppercase command names and their acknowledgment status.

Drone Programming

filtered_ack = [1]([2]: ack_status[[3]] for [3] in commands if ack_status[[3]] == 'SUCCESS')

Drag options to blanks, or click blank then click option'

Adict

Bcmd.upper()

Ccmd

Dlist

Attempts:

3 left

💡 Hint

Common Mistakes

Using list instead of dict which creates a list, not a dictionary.

Using the command name directly instead of uppercase for keys.

The code creates a dictionary with uppercase command names as keys and their acknowledgment status as values, filtering only successful acknowledgments.

Practice

1.

What is the main purpose of command acknowledgment in drone programming?

easy

A. To confirm the drone received and understood the command

B. To increase the drone's flying speed

C. To recharge the drone's battery remotely

D. To change the drone's camera settings automatically

Solution

1. Step 1: Understand command acknowledgment

   Command acknowledgment means the drone sends back a message confirming it got the command.

2. Step 2: Identify the purpose

   This confirmation ensures the command was received and understood, which is critical for safe control.

3. Final Answer:

   To confirm the drone received and understood the command -> Option A

4. Quick Check:

   Command acknowledgment = Confirm command received [OK]

Hint: Acknowledgment means confirmation of command receipt [OK]

Common Mistakes:

• Confusing acknowledgment with drone speed control
• Thinking acknowledgment changes hardware settings
• Assuming acknowledgment recharges battery

2.

Which of the following code snippets correctly checks if a drone command acknowledgment is received?

if response == 'ACK':
    print('Command confirmed')
else:
    print('No confirmation')

easy

A. if response = 'ACK':

B. if response == 'ACK':

C. if response === 'ACK':

D. if response != 'ACK':

Solution

1. Step 1: Identify correct equality operator

   In Python, '==' checks if two values are equal, which is needed here.

2. Step 2: Review options

   '=' is assignment, '===' is not valid in Python, '!=' means not equal, so only '==' is correct.

3. Final Answer:

   if response == 'ACK': -> Option B

4. Quick Check:

   Equality check uses '==' in Python [OK]

Hint: Use '==' to compare values in Python conditions [OK]

Common Mistakes:

• Using single '=' instead of '==' for comparison
• Using '===' which is JavaScript syntax, not Python
• Confusing '!=' with equality check

3.

What will be the output of this code snippet handling drone command acknowledgment?

response = 'NACK'
if response == 'ACK':
    print('Command successful')
else:
    print('Command failed')

medium

A. Command successful

B. SyntaxError

C. Command failed

D. No output

Solution

1. Step 1: Check the response value

   The variable response is set to 'NACK', which means negative acknowledgment.

2. Step 2: Evaluate the if condition

   The condition checks if response equals 'ACK'. Since it is 'NACK', the else block runs.

3. Final Answer:

   Command failed -> Option C

4. Quick Check:

   response != 'ACK' triggers else [OK]

Hint: If response isn't 'ACK', else block runs [OK]

Common Mistakes:

• Assuming 'NACK' means success
• Expecting no output when else runs
• Confusing syntax error with logic error

4.

Identify the error in this drone command acknowledgment code snippet:

response = get_drone_response()
if response = 'ACK':
    print('Command confirmed')
else:
    print('No confirmation')

medium

A. No else block present

B. Missing parentheses in print statements

C. Incorrect function name 'get_drone_response'

D. Using '=' instead of '==' in the if condition

Solution

1. Step 1: Check the if condition syntax

   The condition uses '=' which assigns value, but comparison needs '=='.

2. Step 2: Verify other parts

   Print statements have parentheses, function name is assumed correct, else block exists.

3. Final Answer:

   Using '=' instead of '==' in the if condition -> Option D

4. Quick Check:

   Comparison uses '==' not '=' [OK]

Hint: Use '==' for comparison, '=' is assignment [OK]

Common Mistakes:

• Confusing assignment '=' with equality '=='
• Thinking print needs no parentheses in Python 3
• Assuming function name is wrong without context

5.

You want to send a command to a drone and wait for acknowledgment with a timeout of 5 seconds. Which approach correctly handles this?

import time

def send_command_with_ack(command):
    send_command(command)
    start = time.time()
    while time.time() - start < 5:
        response = get_drone_response()
        if response == 'ACK':
            return 'Success'
    return 'Timeout'

hard

A. The code waits up to 5 seconds for 'ACK', then returns 'Timeout' if none

B. The code immediately returns 'Timeout' without waiting

C. The code waits forever until 'ACK' is received

D. The code returns 'Success' without checking response

Solution

1. Step 1: Analyze the timeout loop

   The while loop runs while elapsed time is less than 5 seconds, checking for 'ACK'.

2. Step 2: Check return behavior

   If 'ACK' is received, returns 'Success'; if time exceeds 5 seconds without 'ACK', returns 'Timeout'.

3. Final Answer:

   The code waits up to 5 seconds for 'ACK', then returns 'Timeout' if none -> Option A

4. Quick Check:

   Timeout loop waits max 5 seconds for acknowledgment [OK]

Hint: Use time check loop to wait with timeout [OK]

Common Mistakes:

• Not implementing timeout, causing infinite wait
• Returning timeout immediately without waiting
• Ignoring response check before returning success