ROS2 Off-board drone control with DDS and PX4

High-level path planning and off-board control of a Pixhawk flight computer running PX4 with a Raspberry Pi 4B. The code is written in C++ and Python in a ROS2 Humble interface.

Custom drone built from scratch

• T-Motor motors, ESCs and propellers
• Pixhawk 6X Flight computer (PX4 v1.14)
• Raspberry Pi 4B (Ubuntu 22.04, ROS2 HUMBLE)
• RTK + Base station
• Tarot 680 Pro Sport frame

Simple take-off -> hover -> land

IMG_9274.mp4

Prerequisites:

• Ubuntu 22.04
• Python3
• C++
• ROS2 Humble

Installation & Setup guide

Ground control station

• Install Qgroundcontrol

Pixhawk 6X setup

• PX4 v1.14 for new Micro XRCE-DDS capabilities

• NOTE version 1.14 is now a stable version so do not have to build from source anymore you can use QGC to install it

• Build v1.14 instructions here

    git clone https://github.com/PX4/PX4-Autopilot.git --recursive
    git checkout release/v1.14
    make px4_fmu-v6x_default upload # Plug in Pixhawk before running this
  

• If not using DDS, but serial and mavsdk then PX4 v1.13 -> This enables HITL

Setup on drone control computer (Laptop for SITL or RPi 4 on drone)

• Install ROS2 Humble

• ROS2 Off-board drone control

    git clone git@github.com:Marnonel6/ROS2_offboard_drone_control.git
  

  • To clone the ROS2 control package an alias with the deployment key also exists on the Pi. Use:

      osprey_code_pull
    

• Setup Micro XRCE-DDS Agent

    git clone https://github.com/eProsima/Micro-XRCE-DDS-Agent.git
    cd Micro-XRCE-DDS-Agent
    mkdir build
    cd build
    cmake ..
    make
    sudo make install
    sudo ldconfig /usr/local/lib/
  

• Fields2Cover Fork or Fields2Cover

    sudo apt-get update
    sudo apt-get install --no-install-recommends software-properties-common
    sudo add-apt-repository ppa:ubuntugis/ppa
    sudo apt-get update
    sudo apt-get install --no-install-recommends build-essential ca-certificates cmake \
        doxygen g++ git libeigen3-dev libgdal-dev libpython3-dev python3 python3-pip \
        python3-matplotlib python3-tk lcov libgtest-dev libtbb-dev swig libgeos-dev
    python3 -m pip install gcovr
  
    git clone git@github.com:Marnonel6/Fields2Cover.git
    cd Fields2Cover
    mkdir -p build;
    cd build;
    cmake -DCMAKE_BUILD_TYPE=Release ..;
    make -j$(nproc);
    sudo make install;
  

  • On RPi I have a deployment key with an alias in the .bashrc file to clone the repo. Use: fields2cover_code_pull

PX4 SITL Simulation with (Ignition) Gazebo setup (On Ubuntu Laptop)

• Install PX4 development environment

    cd
    git clone https://github.com/PX4/PX4-Autopilot.git --recursive
    bash ./PX4-Autopilot/Tools/setup/ubuntu.sh
    !!! Relogin or reboot computer before proceeding !!!
    cd PX4-Autopilot/
    make px4_sitl
  

SITL simulation:

• Start the simulation (On Ubuntu Laptop):

    make px4_sitl gz_x500
  

• Start Qgroundcontrol

• Start the DDS agent on the drone control computer:

    MicroXRCEAgent udp4 -p 8888
  

• Running ros2 topic list should now display all the flight computer topics

• Alternatively to running the agent you can run the off-board control ROS2 package with:

    ros2 launch drone_control offboard_control.launch.py 
  

• This will plan a path and then control the drone to follow the path.

Steps to run off-board autonomous mission on drone:

• Start Qgroundcontrol

• Run the launch file to start the agent and all the nodes:

    ros2 launch drone_control offboard_control.launch.py 
  

• This will plan a path and then control the drone to follow the path.

References

• PX4 DDS topics
• Simple ROS2 sensor reader package here