flock2flock2 can fly a swarm of DJI Tello drones.
flock2 is built on top of ROS2,
fiducial_vlam,
and tello_ros.
Set up a Ubuntu 20.04 box or VM.
Use your favorite Python package manager to set up Python 3.6+ and the following packages:
Install ROS2 Foxy with the ros-foxy-desktop option.
If you install binaries, be sure to also install the development tools and ROS tools from the source installation instructions.
Install these additional packages:
sudo apt install ros-foxy-cv-bridge ros-foxy-camera-calibration-parsers ros-foxy-gazebo-rosDownload, compile and install the following packages:
mkdir -p ~/flock2_ws/src
cd ~/flock2_ws/src
git clone https://github.com/clydemcqueen/flock2.git
git clone https://github.com/clydemcqueen/tello_ros.git
git clone https://github.com/ptrmu/fiducial_vlam.git
git clone https://github.com/ptrmu/ros2_shared.git
cd ..
source /opt/ros/foxy/setup.bash
# If you didn't install Gazebo, avoid building tello_gazebo:
colcon build --event-handlers console_direct+ --packages-skip tello_gazebolaunch_one.py will allow you to fly a drone using a wired XBox One gamepad.
Turn on the drone, connect to TELLO-XXXXX via wifi, and launch ROS2:
cd ~/flock2_ws
source install/setup.bash
ros2 launch flock2 launch_one.pyGamepad controls:
launch_two.py provides an example for flying multiple drones.
Key elements of multi-drone missions:
flock_base should have exactly 1 instance running.
Per-drone nodes such as drone_base should have 1 instance running per drone.solo.ROS world coordinate frames are ENU (East, North, Up).
There are 3 significant coordinate frames in flock2:
mapbase_linkcamera_frameAn arena is a right rectangular prism defined by 2 points: (x1=0, y1=0, z1=0) and (x2, y2, z2). z1 defines the ground, so z2 must be positive. The ground must be flat. Drones will never fly outside of the arena.
There must be at least one 6x6 ArUco marker, with id 1, associated with the arena. Marker 1's pose is known in advance, the other ArUco marker poses are estimated during flight. The drones will use ArUco marker poses to estimate their current pose.
A mission is defined as autonomous flight by all drones. A mission is initiated when the user hits the start mission button on the gamepad. A mission will end on it's own, or when the user hits the stop mission button.
All drones must be able to localize on the ground to start a mission. In practice this means that all drones must be able to see marker 1 while sitting on the ground, or at least one drone has to be flown around manually to build a good map before the mission starts.
The overall mission dataflow looks like this:
flock_base publishes a message on the /start_mission topicplanner_node generates an overall pattern of flight for all drones, and publishes a
sequence waypoints for each drone on /[prefix]/plandrone_base subscribes to ~plan and ~base_odom, runs a PID controller,
and sends commands to tello_rosIf odometry stops arriving drone_base will execute a series of recovery tasks, which might include landing.
If flight indicates that a drone has a low battery drone_base will land the drone.
Install Gazebo 9 and build tello_gazebo, if you haven't already.
cd ~/flock2_ws
source install/setup.bash
export GAZEBO_MODEL_PATH=${PWD}/install/tello_gazebo/share/tello_gazebo/models
source /usr/share/gazebo/setup.sh
ros2 launch flock2 gazebo_launch.pyHit the "B" button on the XBox controller to start the mission. You should see 4 drones take off, rotate through 4 positions, then land.
Orchestrates the flight of one or more Tello drones.
~joy sensor_msgs/Joy/start_mission std_msgs/Empty/stop_mission std_msgs/Empty~[prefix]/joy sensor_msgs/Joydrones is an array of strings, where each string is a topic prefixControls a single Tello drone. Akin to move_base in the ROS navigation stack.
/start_mission std_msgs/Empty/stop_mission std_msgs/Empty~joy sensor_msgs/Joy~tello_response tello_msgs/TelloResponse~flight_data tello_msgs/FlightData~base_odom nav_msgs/Odometry~cmd_vel geometry_msgs/Twist~tello_command tello_msgs/TelloCommandCompute and publish a set of waypoints for each drone in a flock.
/start_mission std_msgs/Empty/stop_mission std_msgs/Empty~[prefix]/base_odom nav_msgs/Odometry~[prefix]/plan nav_msgs/Pathdrones is an array of strings, where the number of strings is the number of drones and each string is the topic prefix for a drone.
For example, ['d1', 'd2'] refers to 2 drones, and the flight data topic for the first drone is /d1/flight_data.
The default is ['solo'].arena_x defines the X extent of the arena, in meters. The default is 2.arena_y defines the Y extent of the arena, in meters. The default is 2.arena_z defines the Z extent of the arena, in meters. Must be greater than 1.5. The default is 2.flock2 was developed along with several other projects while ROS2 was rapidly changing.
All of the related projects adopted similar conventions around branch names:
master branch works with the latest ROS2 release (Foxy as of this writing)crystal, dashing or eloquentThe following projects and branches were tested together: