Companion computer integration (Raspberry Pi) in Drone Programming - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the MAVLink library on the Raspberry Pi.

Drone Programming

import [1]

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

Atime

Bdronekit

Cpymavlink

Dserial

Attempts:

3 left

💡 Hint

Common Mistakes

Importing 'dronekit' instead of 'pymavlink' when direct MAVLink communication is needed.

The pymavlink library is used to communicate with the drone via MAVLink protocol on the Raspberry Pi.

2fill in blank

medium

Complete the code to open a serial connection to the drone on the Raspberry Pi.

Drone Programming

connection = serial.Serial('[1]', 57600)

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

A/dev/ttyS0

B/dev/ttyAMA0

C/dev/ttyUSB0

D/dev/ttyACM0

Attempts:

3 left

💡 Hint

Common Mistakes

Using USB serial ports like /dev/ttyUSB0 which may not be connected to the flight controller.

The Raspberry Pi commonly uses /dev/ttyAMA0 for serial communication with the flight controller.

3fill in blank

hard

Fix the error in the code to send a heartbeat message to the drone.

Drone Programming

msg = mavutil.mavlink.MAVLink_heartbeat_message([1], 0, 0, 0, 0)

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

A3

B1

C5

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 or 1 which represent other system types and cause communication issues.

The system type for a companion computer is usually set to 3 when sending heartbeat messages.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps sensor names to their readings only if the reading is above 10.

Drone Programming

sensor_data = {name: [1] for name, [2] in sensors.items() if value > 10}

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

Avalue

Breading

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names for the reading in the comprehension causing errors.

The dictionary comprehension uses value as the variable for sensor readings in both places.

5fill in blank

hard

Fill all three blanks to filter telemetry data where altitude is above 100 and map the drone ID to altitude.

Drone Programming

filtered = [1] for drone_id, [2] in telemetry.items() if [3] > 100

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

A{drone_id:

Baltitude

Caltitude}

D[drone_id:

Attempts:

3 left

💡 Hint

Common Mistakes

Using square brackets instead of curly braces for dictionary comprehension.

The code creates a dictionary comprehension mapping drone_id to altitude when altitude is above 100.

Practice

1. What is the main role of a Raspberry Pi when used as a companion computer in drone programming?

easy

A. To add smart features and process data alongside the drone's flight controller

B. To replace the drone's flight controller completely

C. To act as a remote control for the drone

D. To charge the drone's batteries during flight

Solution

1. Step 1: Understand the companion computer concept

   A companion computer like Raspberry Pi works alongside the drone's flight controller to add extra processing power and smart features.

2. Step 2: Identify the Raspberry Pi's role

   It does not replace the flight controller but supports it by handling tasks like image processing or advanced navigation.

3. Final Answer:

   To add smart features and process data alongside the drone's flight controller -> Option A

4. Quick Check:

   Companion computer = extra smart features [OK]

Hint: Remember: companion computer supports, not replaces flight controller [OK]

Common Mistakes:

• Thinking Raspberry Pi replaces the flight controller
• Confusing companion computer with remote control
• Assuming it charges the drone

2. Which of the following is the correct way to import the DroneKit library in a Python script running on a Raspberry Pi?

easy

A. import DroneKit

B. from dronekit import connect

C. import dronekit

D. import drone_kit

Solution

1. Step 1: Recall DroneKit import syntax

   The DroneKit library is imported using 'from dronekit import connect' to access the connect function directly.

2. Step 2: Check case sensitivity and module name

   Python is case sensitive; 'DroneKit' or 'drone_kit' are incorrect module names.

3. Final Answer:

   from dronekit import connect -> Option B

4. Quick Check:

   Correct import syntax = from dronekit import connect [OK]

Hint: Use exact lowercase 'dronekit' and import needed functions [OK]

Common Mistakes:

• Using wrong capitalization in module name
• Trying to import the whole module without specifying functions
• Misspelling the library name

3. Given the following Python code snippet on a Raspberry Pi connecting to a drone via UDP:

from dronekit import connect
vehicle = connect('udp:127.0.0.1:14550', wait_ready=True)
print(vehicle.mode.name)

What will this code output if the drone is in GUIDED mode?

medium

A. guided

B. Mode GUIDED not found

C. GUIDED

D. SyntaxError

Solution

1. Step 1: Understand vehicle.mode.name output

   The mode name property returns the mode as an uppercase string, e.g., 'GUIDED'.

2. Step 2: Check the print output for GUIDED mode

   Since the drone is in GUIDED mode, the output will be 'GUIDED' in uppercase.

3. Final Answer:

   GUIDED -> Option C

4. Quick Check:

   vehicle.mode.name returns uppercase mode [OK]

Hint: DroneKit mode names print in uppercase strings [OK]

Common Mistakes:

• Expecting lowercase mode names
• Confusing attribute access syntax
• Assuming code causes syntax error

4. You wrote this code on your Raspberry Pi to connect to a drone via serial port:

from dronekit import connect
vehicle = connect('/dev/ttyUSB0', baud=57600, wait_ready=True)
print(vehicle.battery.level)

But you get an error: TypeError: connect() got an unexpected keyword argument 'baud'. What is the fix?

medium

A. Change 'baud' to 'baudrate' in the connect() call

B. Remove 'wait_ready=True' from connect()

C. Use 'baud' but set it to 115200 instead

D. Change '/dev/ttyUSB0' to 'udp:127.0.0.1:14550'

Solution

1. Step 1: Identify the correct parameter name for baud rate

   The connect() function expects 'baudrate' not 'baud' as the keyword argument for serial speed.

2. Step 2: Fix the parameter name in the code

   Replace 'baud=57600' with 'baudrate=57600' to fix the TypeError.

3. Final Answer:

   Change 'baud' to 'baudrate' in the connect() call -> Option A

4. Quick Check:

   Correct parameter name = baudrate [OK]

Hint: Use 'baudrate' keyword, not 'baud' in connect() [OK]

Common Mistakes:

• Using 'baud' instead of 'baudrate'
• Changing connection type unnecessarily
• Removing wait_ready without cause

5. You want your Raspberry Pi companion computer to monitor the drone's battery and land the drone automatically if battery level falls below 20%. Which code snippet correctly implements this logic using DroneKit?

hard

A. if vehicle.battery.level < 20:
vehicle.mode = vehicle.mode.LAND

B. if vehicle.battery.level < 20:
vehicle.mode = vehicle.mode.name('LAND')

C. if vehicle.battery.level < 20:
vehicle.mode = vehicle.mode('LAND')

D. if vehicle.battery.level < 20:
vehicle.mode = 'LAND'

Solution

1. Step 1: Understand how to set vehicle mode

   To change the drone mode, assign a string like 'LAND' directly to vehicle.mode.

2. Step 2: Check the battery level condition

   If battery level is below 20%, set vehicle.mode = 'LAND' to command landing.

3. Final Answer:

   if vehicle.battery.level < 20: vehicle.mode = 'LAND' -> Option D

4. Quick Check:

   Set mode by assigning string name directly [OK]

Hint: Assign mode as string like 'LAND' to vehicle.mode [OK]

Common Mistakes:

• Trying to call mode as a function
• Using mode.name or mode.LAND incorrectly
• Not comparing battery level properly