Companion computer integration (Raspberry Pi) in Drone Programming - Step-by-Step Execution

Concept Flow - Companion computer integration (Raspberry Pi)

Start Raspberry Pi

↓

Initialize communication

↓

Connect to flight controller

↓

Send/Receive data

↓

Process commands

↓

Control drone or log data

↓

Loop or End

The Raspberry Pi starts, sets up communication with the drone's flight controller, exchanges data, processes commands, and controls or logs drone activity in a loop.

Execution Sample

Drone Programming

import dronekit

vehicle = dronekit.connect('/dev/ttyAMA0', baud=57600)
print(vehicle.location.global_frame)

Connects Raspberry Pi to drone flight controller and prints current GPS location.

Execution Table

Step	Action	Evaluation	Result
1	Import dronekit library	Success	dronekit module ready
2	Connect to flight controller at /dev/ttyAMA0 with baud 57600	Connection attempt	Vehicle object created
3	Access vehicle.location.global_frame	Retrieve GPS data	Prints current GPS coordinates
4	End of script	No errors	Program stops

💡 Script ends after printing GPS location

Variable Tracker

Variable	Start	After Step 2	After Step 3	Final
vehicle	None	Connected vehicle object	Vehicle location data available	Vehicle object with location

Key Moments - 3 Insights

Why do we specify '/dev/ttyAMA0' and baud rate when connecting?

Because the Raspberry Pi communicates with the flight controller over a serial port, specifying the correct device and baud rate ensures proper connection, as shown in execution_table step 2.

What does vehicle.location.global_frame represent?

It represents the drone's current GPS coordinates, accessed after connection in execution_table step 3.

What happens if the connection fails at step 2?

The vehicle object won't be created, causing errors in later steps; the program would stop or raise exceptions.

Visual Quiz - 3 Questions

Look at the execution_table, what is the result after step 2?

A GPS coordinates printed

B Vehicle object created

C Program ends

D Import error

💡 Hint

Refer to execution_table row with Step 2 under Result column

At which step does the program print the drone's GPS location?

A Step 3

B Step 2

C Step 1

D Step 4

💡 Hint

Check execution_table row with Step 3 under Action and Result

If the baud rate is incorrect, what will most likely happen in the execution?

A Vehicle object connects successfully

B Import dronekit fails

C Connection fails at step 2

D GPS data prints incorrectly at step 3

💡 Hint

Consider execution_table step 2 connection attempt and what affects it

Concept Snapshot

Companion computer integration with Raspberry Pi:
- Use dronekit to connect via serial port (e.g., '/dev/ttyAMA0')
- Specify correct baud rate (e.g., 57600)
- Access vehicle data like GPS via vehicle.location.global_frame
- Process data or send commands in a loop
- Proper connection is essential for communication

Full Transcript

This visual execution shows how a Raspberry Pi connects to a drone's flight controller using the dronekit library. First, the program imports dronekit, then connects to the flight controller over a serial port with a specified baud rate. After connection, it accesses and prints the drone's GPS location. The execution table traces each step, showing the creation of the vehicle object and retrieval of location data. Variables like 'vehicle' change from None to a connected object holding location info. Key moments clarify why the serial port and baud rate matter, what GPS data means, and what happens if connection fails. The quiz tests understanding of these steps. The snapshot summarizes the main points for quick recall.

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