Master the integration of ROS2, PX4, and OpenCV to achieve precision landing using ArUco marker detection. This tutorial delves into how to leverage ROS2's robust communication framework and PX4's flight control system to implement highly accurate landings for autonomous drones. You'll learn how to configure your environment, process camera feeds, and detect ArUco markers in real-time, enabling your drone to land precisely at designated targets. Whether you're new to drone development or an experienced engineer, this guide provides a step-by-step approach to achieving reliable precision landing with seamless integration into your ROS2 and PX4 projects.
Aruco markers are square fiducial markers used in computer vision for tasks like pose estimation, camera calibration, and augmented reality (AR). Each marker has a unique binary pattern inside a black border, allowing it to be easily detected and identified. They help in determining the position and orientation of cameras or objects in a scene, making them valuable in robotics, navigation, and AR applications. https://docs.opencv.org/4.x/d5/dae/tutorial_aruco_detection.html
- Ubuntu 22.04
- ROS2 Humble
- PX4 Autopilot with an ArUco Marker and downward facing camera
- Micro XRCE-DDS Agent
- QGroundControl Daily Build
- OpenCV 4.10.0
- ROS_GZ bridge
You can find the required instructions collected below
https://docs.px4.io/main/en/ros2/user_guide.html https://docs.qgroundcontrol.com/master/en/qgc-user-guide/releases/daily_builds.html
You need the lates PX4-Autopilot, that will contain the required drone with the downward facing camera and the world that has the aruco marker in it To get ros_gz bridge
sudo apt install ros-humble-ros-gzgarden
https://github.com/gazebosim/ros_gz
For the OpenCV part follow the instructions below
Make sure you source ROS2 Humble in the terminal you are using.
source /opt/ros/humble/setup.bash
OR Just add the line above to your bashrc, in that case it is going to be sourced every time you open a terminal.
nano ~/.bashrc
Navigate to the directory you would like to place the worskpace and then run the following
git clone https://github.com/ARK-Electronics/tracktor-beam.git
Then navigate into the workspace:
cd tracktor-beam
Install OpenCV from source
./install_opencv.sh
Install the submoduls
git submodule update --init --recursive
Build the workspace
colcon build
After this runs, we do not need to build the whole workspace again, you can just build the individual packages you have modified
colcon build --packages-select precision_land
Source the workspace
source install/setup.bash
Launch PX4 sim
make px4_sitl gz_x500_mono_cam_down_aruco
Launch micro dds
MicroXRCEAgent udp4 -p 8888
Launch the ros_gz_bridge for getting the camera topic
ros2 run ros_gz_bridge parameter_bridge /camera@sensor_msgs/msg/[email protected]
Launch the ros_gz_bridge for getting the camera info topic (this is how we get camera intrinsics)
ros2 run ros_gz_bridge parameter_bridge /camera_info@sensor_msgs/msg/[email protected]
Launch the ros2 nodes (aruco_tracker)
cd tracktor-beam/
source install/setup.bash
ros2 run aruco_tracker aruco_tracker
OR Launch file with the bridges:
source install/setup.bash
ros2 launch aruco_tracker aruco_tracker.launch.py
View the video (/image_proc is the annoted image)
ros2 run rqt_image_view rqt_image_view
Launch the ros2 nodes (precision_land)
cd tracktor-beam/
source install/setup.bash
ros2 run precision_land precision_land
OR Launch file with the params:
ros2 launch precision_land precision_land.launch.py
Once the nodes are running the Precision Land mode is going to show up in QGC
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Message Patrik Dominik Pordi on the ARK Electronics / Dronecode Foundation Discord for questions or email me at [email protected]
- Ubuntu 22.04
- ROS2 Humble
- Drone with downward facing camera
- Micro XRCE-DDS Agent
- QGroundControl
- OpenCV 4.10.0
- Camera node: I use an usb camera, there is a ROS2 package already out there for it: https://github.com/ros-drivers/usb_cam.git
You can either run the the nodes or turn them into a service, that starts at boot:
First, you need to move your service file to the /etc/systemd/system/ directory, where systemd can find it. Replace myservice.service with the actual name of your service file.
Ensure that the service file has the correct permissions. Typically, it should be readable by all users:
sudo chmod 644 /etc/systemd/system/myservice.service
After copying the service file, reload the systemd daemon to recognize the new service:
sudo systemctl daemon-reload
Start the service using systemctl:
sudo systemctl start myservice
If you want the service to start automatically on boot, enable it:
sudo systemctl enable myservice
Verify that the service is running correctly:
sudo systemctl status myservice
