Drone [WIP]

2024-06-25.12-36-32.mp4

Introduction

This project is a drone flight system consisting of custom flight hardware, firmware, a Raspberry Pi-based communication bridge, and a ground control station. The ultimate goal is to build a fully autonomous drone capable of takeoff/landing on a target platform.

System Architecture

The system is composed of three main components:

1. Flight Computer with Firmware (Custom PCB with teensy 4.1 microcontroller)
2. Communication Bridge (Raspberry Pi 4B)
3. Ground Control Station (Desktop application using rust egui)

1. Flight Computer

The flight computer is built on a perfboard with a Teensy 4.1 running custom firmware written in C++. It handles real-time flight control, sensor fusion, and motor control.

Key Components:

• Teensy 4.1 microcontroller
• LSM6DSOX + LIS3DML IMU
• BMP390L Barometer
• ublox M9N GPS

Firmware Structure:

The firmware is modular and consists of several key components:

1. main.cpp: The entry point of the firmware, handling initialization and the main control loop.
2. filter.h: Implements sensor fusion using a Madgwick or Mahony filter to estimate the drone's orientation.
3. pid.h: Implements a simplified PID controller for only roll control for testing.
4. state.h: Manages the drone's state and LED indicators.
5. transmitter.h: Handles communication with the Raspberry Pi.
6. consts.h: Defines constants used throughout the firmware.
7. baro.h: Interfaces with the barometric pressure sensor.
8. imu.h: Interfaces with the IMU sensor for accelerometer and gyroscope data.
9. motor.h: Controls the drone's motors based on the PID output. Has functions for arming, disarming, and setting motor speeds. I also contains hardware interrupt handlers if the signal is not received for a certain time.

2. Communication Bridge (Raspberry Pi)

The Raspberry Pi acts as a bridge between the flight computer and the ground control station. It runs a Rust application that:

1. Communicates with the flight computer via UART
2. Hosts a WebSocket server for real-time communication with the ground control station
3. Optionally processes computer vision tasks (e.g., ArUco marker detection)

Key Components:

• Raspberry Pi 4 Model B
• Camera module (for computer vision tasks)
• Wi-Fi module for communication with the ground station

Rust Application Structure:

use tokio::net::TcpListener;
use tokio_serial::SerialPortBuilderExt;
use tokio_tungstenite::accept_async;

async fn handle_connection(stream: TcpStream) {
    let ws_stream = accept_async(stream).await.unwrap();
    let (mut ws_sender, mut ws_receiver) = ws_stream.split();

    let serial = tokio_serial::new("/dev/ttyS0", 1_000_000).open_native_async().unwrap();
    let (serial_reader, mut serial_writer) = tokio::io::split(serial);

    // ... (WebSocket and serial communication logic)
}

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let listener = TcpListener::bind("0.0.0.0:8765").await?;

    while let Ok((stream, _)) = listener.accept().await {
        tokio::spawn(handle_connection(stream));
    }

    Ok(())
}

3. Ground Control Station

The ground control station is a desktop application written in Rust using the egui. It provides a user interface for monitoring telemetry, controlling the drone, and adjusting flight parameters.

Key Features:

• Real-time telemetry display
• 3D attitude visualization
• PID tuning interface
• RC control emulation
• Command interface for sending instructions to the drone

Rust Application Structure:

mod accelerometer_view;
mod app;
mod attitude_view;
mod chat_view;
mod commands_view;
mod data;
mod drone_view;
mod pid_view;
mod rc_control;
mod rc_view;

use app::MyApp;
use eframe::egui;

fn main() -> Result<(), eframe::Error> {
    let options = eframe::NativeOptions {
        viewport: egui::ViewportBuilder::default().with_maximized(true),
        ..Default::default()
    };
    eframe::run_native(
        "Drone Control",
        options,
        Box::new(move |cc| {
            egui_extras::install_image_loaders(&cc.egui_ctx);
            Box::new(MyApp::new())
        }),
    )
}

The MyApp struct manages the overall application state and UI layout:

pub struct MyApp {
    drone_view: DroneView,
    attitude_view: AttitudeView,
    accelerometer_view: AccelerometerView,
    rc_view: RCView,
    rc_control: RCControl,
    pid_control: PIDControlView,
    chat_view: ChatView,
    commands_view: CommandsView,
    received_data: Arc<Mutex<ReceivedData>>,
    // ... (other fields)
}

Getting Started

To use this system with your own drone project:

1. Flight Computer Setup:

   • Flash the custom firmware onto your microcontroller
   • Connect sensors and motors according to the pin definitions in consts.h

2. Raspberry Pi Setup:

   • Install Rust locally and run sudo apt install -y gcc-aarch64-linux-gnu to cross-compile for the Raspberry Pi
   • Built the code using cargo build --release and copy the binary to the Raspberry Pi
   • Copy the binary to the Raspberry Pi and run the executable

3. Ground Control Station Setup:

   • Build and run the application using cargo run --release

Future Improvements

• Implement full attitude control (pitch and yaw in addition to roll)
• Integrate computer vision for target tracking and landing using ArUco markers.
• Add GPS support for position hold and waypoint navigation

License

This project is licensed under the MIT License - see the LICENSE file for details.