Companion computer integration (Raspberry Pi) in Drone Programming - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a companion computer in drone systems?

A companion computer is a small, powerful computer like a Raspberry Pi that works alongside the drone's main flight controller to handle complex tasks such as image processing, navigation, and communication.

beginner

How does a Raspberry Pi communicate with a drone's flight controller?

The Raspberry Pi usually communicates with the flight controller using serial connections like UART or USB, sending and receiving data such as commands and telemetry.

intermediate

Why use a Raspberry Pi as a companion computer instead of the flight controller alone?

Because Raspberry Pi can run full operating systems and complex software, it can handle advanced tasks like computer vision or AI that the flight controller cannot do efficiently.

intermediate

What software tools are commonly used on Raspberry Pi for drone companion computing?

Common tools include MAVLink for communication, ROS (Robot Operating System) for robotics control, and OpenCV for image processing.

beginner

What is the role of MAVLink in companion computer integration?

MAVLink is a lightweight communication protocol that allows the Raspberry Pi to send commands and receive telemetry data from the flight controller, enabling coordinated control.

What type of connection is commonly used between a Raspberry Pi and a drone's flight controller?

A Serial (UART or USB)

B Wi-Fi only

C Bluetooth only

D Ethernet cable

Serial connections like UART or USB are commonly used for reliable communication between Raspberry Pi and flight controllers.

Which software protocol helps the Raspberry Pi communicate with the flight controller?

A HTTP

B MAVLink

C FTP

D SMTP

MAVLink is the standard protocol for communication between companion computers and flight controllers.

Why is a Raspberry Pi preferred for companion computing over the flight controller alone?

A It is cheaper

B It replaces the flight controller

C It has a bigger battery

D It can run complex software and handle advanced tasks

Raspberry Pi can run full operating systems and complex programs, enabling advanced processing beyond the flight controller's capabilities.

Which of these is NOT a typical task for a Raspberry Pi companion computer on a drone?

A Image processing

B Navigation assistance

C Flight stabilization

D Telemetry data handling

Flight stabilization is usually handled by the flight controller, not the companion computer.

What is ROS commonly used for in Raspberry Pi drone integration?

A Robot Operating System for control and communication

B Operating system for flight controllers

C Image editing software

D Battery management

ROS stands for Robot Operating System and helps manage control, communication, and sensor data on companion computers.

Explain how a Raspberry Pi acts as a companion computer in a drone system and why it is useful.

Think about what the flight controller cannot do alone.

Describe the communication process between a Raspberry Pi and a drone's flight controller.

Focus on how data moves back and forth.

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