Vehicle state reading (location, attitude, battery) in Drone Programming - Mini Project: Build & Apply

Vehicle state reading (location, attitude, battery)

📖 Scenario: You are programming a drone to monitor its current state. The drone provides data about its location, attitude (orientation), and battery level. You want to read and display this information clearly.

🎯 Goal: Build a simple program that stores the drone's state data, sets a battery warning level, extracts the important state details, and then prints the current location, attitude, and battery status.

📋 What You'll Learn

Create a dictionary called vehicle_state with keys location, attitude, and battery and their exact values

Create a variable called battery_warning_level set to 20

Create a new dictionary called important_state that includes only the location and battery from vehicle_state if the battery is below the warning level

Print the important_state dictionary

💡 Why This Matters

🌍 Real World

Drones and other vehicles often need to monitor their location, orientation, and battery to operate safely and efficiently.

💼 Career

Understanding how to read and filter vehicle state data is important for drone operators, robotics engineers, and embedded system developers.

1

Create the vehicle state dictionary

Create a dictionary called vehicle_state with these exact entries: 'location': {'latitude': 34.05, 'longitude': -118.25}, 'attitude': {'roll': 0.1, 'pitch': 0.0, 'yaw': 1.5}, and 'battery': 18.

Drone Programming

# Create the vehicle_state dictionary with location, attitude, and battery
# Your code here

Hint

Use curly braces {} to create a dictionary. Include nested dictionaries for location and attitude.

2

Set the battery warning level

Create a variable called battery_warning_level and set it to 20.

Drone Programming

vehicle_state = {
    'location': {'latitude': 34.05, 'longitude': -118.25},
    'attitude': {'roll': 0.1, 'pitch': 0.0, 'yaw': 1.5},
    'battery': 18
}
# Set battery_warning_level to 20
# Your code here

Hint

Just assign the number 20 to the variable battery_warning_level.

3

Create important state dictionary based on battery level

Create a dictionary called important_state that includes the location and battery from vehicle_state only if the battery is less than battery_warning_level. Otherwise, create an empty dictionary.

Drone Programming

vehicle_state = {
    'location': {'latitude': 34.05, 'longitude': -118.25},
    'attitude': {'roll': 0.1, 'pitch': 0.0, 'yaw': 1.5},
    'battery': 18
}
battery_warning_level = 20
# Create important_state dictionary based on battery level
# Your code here

Hint

Use an if statement to check battery level and create the dictionary accordingly.

4

Print the important state

Write a print statement to display the important_state dictionary.

Drone Programming

vehicle_state = {
    'location': {'latitude': 34.05, 'longitude': -118.25},
    'attitude': {'roll': 0.1, 'pitch': 0.0, 'yaw': 1.5},
    'battery': 18
}
battery_warning_level = 20
if vehicle_state['battery'] < battery_warning_level:
    important_state = {
        'location': vehicle_state['location'],
        'battery': vehicle_state['battery']
    }
else:
    important_state = {}
# Print the important_state dictionary
# Your code here

Hint

Use print(important_state) to show the dictionary.

Practice

1. What does the vehicle.location.global_frame property represent in drone programming?

easy

A. The drone's battery percentage

B. The drone's current GPS coordinates (latitude, longitude, altitude)

C. The drone's orientation angles (roll, pitch, yaw)

D. The drone's speed in meters per second

Solution

1. Step 1: Understand the property name

   vehicle.location.global_frame refers to the drone's global position in the world.

2. Step 2: Identify what global_frame means

   Global frame means GPS coordinates: latitude, longitude, and altitude.

3. Final Answer:

   The drone's current GPS coordinates (latitude, longitude, altitude) -> Option B

4. Quick Check:

   Location = GPS coordinates [OK]

Hint: Global frame means GPS location, not battery or angles [OK]

Common Mistakes:

• Confusing location with battery status
• Mixing attitude (orientation) with location
• Thinking global_frame is speed

2. Which of the following is the correct way to read the drone's battery level in percentage using the vehicle object?

easy

A. battery_level = vehicle.battery.remaining

B. battery_level = vehicle.battery.level

C. battery_level = vehicle.battery.level_percent

D. battery_level = vehicle.battery.percent

Solution

1. Step 1: Recall the battery property

   The vehicle object uses vehicle.battery.remaining to get battery percentage.

2. Step 2: Check other options

   Other options like percent, level, or level_percent are not valid properties.

3. Final Answer:

   battery_level = vehicle.battery.remaining -> Option A

4. Quick Check:

   Battery percentage = vehicle.battery.remaining [OK]

Hint: Battery percentage is in vehicle.battery.remaining [OK]

Common Mistakes:

• Using incorrect property names like percent or level
• Confusing battery with location or attitude properties
• Assuming battery is a method, not a property

3. Given the code snippet:

attitude = vehicle.attitude
print(f"Roll: {attitude.roll}, Pitch: {attitude.pitch}, Yaw: {attitude.yaw}")

What will this code output if the drone is perfectly level and facing north?

medium

A. Roll: 0.0, Pitch: 1.57, Yaw: 0.0

B. Roll: 0.0, Pitch: 0.0, Yaw: 1.57

C. Roll: 0.0, Pitch: 0.0, Yaw: 0.0

D. Roll: 1.57, Pitch: 0.0, Yaw: 0.0

Solution

1. Step 1: Understand attitude values for level drone

   A perfectly level drone has roll and pitch near 0 radians, yaw depends on heading.

2. Step 2: Facing north means yaw is 0 radians

   Yaw angle 0 means facing north, so yaw = 0.0.

3. Final Answer:

   Roll: 0.0, Pitch: 0.0, Yaw: 0.0 -> Option C

4. Quick Check:

   Level drone facing north = all zeros [OK]

Hint: Level means roll and pitch zero; north means yaw zero [OK]

Common Mistakes:

• Assuming yaw is 1.57 (90 degrees) for north
• Mixing roll and pitch values
• Confusing radians with degrees

4. Identify the error in this code snippet that tries to print the drone's altitude:

altitude = vehicle.location.global_frame.altitude
print(f"Altitude: {altitude} meters")

medium

A. The property global_frame does not have altitude

B. The print statement syntax is incorrect

C. Altitude should be accessed from vehicle.attitude

D. vehicle.location.global_frame is None before GPS lock

Solution

1. Step 1: Check property availability

   vehicle.location.global_frame.altitude is valid but may be None if GPS is not locked.

2. Step 2: Understand None value issue

   If GPS lock is missing, global_frame is None, so accessing altitude causes error.

3. Final Answer:

   vehicle.location.global_frame is None before GPS lock -> Option D

4. Quick Check:

   GPS lock needed before reading altitude [OK]

Hint: Check if global_frame is None before accessing altitude [OK]

Common Mistakes:

• Assuming altitude is in attitude object
• Ignoring NoneType errors when GPS not ready
• Thinking print syntax is wrong

5. You want to create a function that returns a dictionary with the drone's current latitude, longitude, altitude, roll, pitch, yaw, and battery percentage. Which code snippet correctly does this?

hard

A. def get_state(vehicle):
return {
'lat': vehicle.location.global_frame.lat,
'lon': vehicle.location.global_frame.lon,
'alt': vehicle.location.global_frame.altitude,
'roll': vehicle.attitude.roll,
'pitch': vehicle.attitude.pitch,
'yaw': vehicle.attitude.yaw,
'battery': vehicle.battery.remaining
}

B. def get_state(vehicle):
return {
'lat': vehicle.location.global_frame.latitude,
'lon': vehicle.location.global_frame.longitude,
'alt': vehicle.location.global_frame.altitude,
'roll': vehicle.attitude.roll_angle,
'pitch': vehicle.attitude.pitch_angle,
'yaw': vehicle.attitude.yaw_angle,
'battery': vehicle.battery.percent
}

C. def get_state(vehicle):
return {
'lat': vehicle.location.global_frame.lat,
'lon': vehicle.location.global_frame.lon,
'alt': vehicle.location.global_frame.altitude,
'roll': vehicle.attitude.roll,
'pitch': vehicle.attitude.pitch,
'yaw': vehicle.attitude.yaw,
'battery': vehicle.battery.level
}

D. def get_state(vehicle):
return {
'latitude': vehicle.location.global_frame.latitude,
'longitude': vehicle.location.global_frame.longitude,
'altitude': vehicle.location.global_frame.altitude,
'roll': vehicle.attitude.roll,
'pitch': vehicle.attitude.pitch,
'yaw': vehicle.attitude.yaw,
'battery': vehicle.battery.remaining
}

Solution

1. Step 1: Check property names for location and attitude

   Correct properties are lat, lon, altitude for location and roll, pitch, yaw for attitude.

2. Step 2: Verify battery property and dictionary keys

   Battery percentage is vehicle.battery.remaining. Keys can be short names like 'lat', 'lon', 'alt'.

3. Final Answer:

   The code using correct property names (lat, lon, altitude, roll, pitch, yaw, battery.remaining) -> Option A

4. Quick Check:

   Use correct property names and battery.remaining [OK]

Hint: Use lat, lon, altitude, roll, pitch, yaw, battery.remaining [OK]

Common Mistakes:

• Using wrong property names like latitude or percent
• Mixing attitude property names with _angle suffix
• Using battery.level instead of battery.remaining