Project Pixhawk

Please refer to https://aerostack2.github.io/_02_examples/pixhawk/project_px4_vision/index.html for more information.

Installation

You need to clone and build as2_platform_pixhawk, refer to https://aerostack2.github.io/_03_aerial_platforms/_pixhawk/index.html for more information.

To install this project, clone the repository:

git clone https://github.com/aerostack2/project_px4_vision

To start using this project, please go to the root folder of the project.

Execution

0. Pre-requisites

For this drones, aerostack2 nodes must be launched in the onboard computer of each drone, and the ground station can be launched in both the onboard computer of the drone or in an external computer.

For simulation, we use a docker image for launch Gazebo Garden with the Pixhawk SITL. You need to build it with the following command:

cd sitl_config/docker && ./docker_build.bash

Then, configure the simulation in the sitl_config/world.yaml file. You can change the world, the number of drones, the initial position, etc.

Finally, you need to launch the simulation with the following command:

./launch_sitl.bash

At the execution ends, close tmux sessions with the following command:

./stop_tmuxinator_sitl.bash

1. Launch aerostack2 nodes for each drone

Launch Micro XRCE Agent for each drone:

• For real:

MicroXRCEAgent serial -b 921600 --dev /dev/ttyUSB0

• For simulation:

MicroXRCEAgent udp4 -p 8888

To launch aerostack2 nodes for each drone, execute once the following command:

./launch_as2.bash -n drone0

Re-launch the command for each drone you want to launch, changing the drone namespace with the flag -n.

The flags for the components launcher are:

• -n: select drone namespace to launch. Default is 'drone0'
• -c: motion controller plugin (pid_speed_controller, differential_flatness_controller), choices: [pid, df]. Default: pid
• -x: launch micro_xrce_agent for real flights. Default not launch
• -r: record rosbag. Default not launch
• -g: launch using gnome-terminal instead of tmux. Default not set

2. Launch aerostack2 nodes for the ground station

To launch aerostack2 nodes for the ground station, execute once the following command:

./launch_ground_station.bash -n drone0

The flags for the components launcher are:

• -n: drone namespaces, comma separated. Default is 'drone0'
• -t: launch keyboard teleoperation. Default not launch
• -v: open rviz. Default not launch
• -m: launch mocap4ros2. Default not launch
• -r: record rosbag. Default not launch
• -g: launch using gnome-terminal instead of tmux. Default not set

3. Launch a mission

There are several missions that can be executed:

• AS2 keyboard teleoperation control: You can use the keyboard teleoperation launched with the ground station, using the flag -t:

  ./launch_ground_station.bash -t

• AS2 Python API single drone mission: You can execute a mission that used AS2 Python API, launching the mission with:

  python3 mission.py -n drone0

• AS2 Python API single drone mission using GPS: You can execute a mission that used AS2 Python API with GPS, launching the mission with:

  python3 mission_gps.py -n drone0

• AS2 Mission Interpreter single drone mission: You can execute a mission that used AS2 Mission Interpreter, launching the mission with:

  python3 mission_interpreter.py -n drone0

• AS2 Behavior Trees single drone mission: You can execute a mission that used AS2 Behavior Trees, launching the mission with:

  python3 mission_behavior_tree.py -n drone0

4. End the execution

If you are using tmux, you can end the execution with the following command:

• End the execution of all nodes:

  ./stop_tmuxinator_as2.bash drone0

• End the execution of all nodes of the ground station:

  ./stop_tmuxinator_ground_station.bash

• End the execution of both:

  ./stop_tmuxinator.bash drone0

You can force the end of all tmux sessions with the command:

tmux kill-server

If you are using gnome-terminal, you can end the execution by closing the terminal.

Developers guide

All projects in aerostack2 are structured in the same way. The project is divided into the following directories:

• tmuxinator: Contains the tmuxinator launch file, which is used to launch all aerostack2 nodes.
  • aerostack2.yaml: Tmuxinator launch file for each drone. The list of nodes to be launched is defined here.
  • ground_station.yaml: Tmuxinator launch file for the ground station. The list of nodes to be launched is defined here.
• config: Contains the configuration files for the launchers of the nodes in the drones.
• config_ground_station: Contains the configuration files for the launchers of the nodes in the ground station.
• launch_as2.bash: Script to launch nodes defined in tmuxinator/aerostack2.yaml.
• launch_ground_station.bash: Script to launch nodes defined in tmuxinator/ground_station.yaml.
• mission_*.py: Differents python mission files that can be executed.
• stop_tmuxinator_as2.bash: Script to stop all nodes launched by launch_as2.bash.
• stop_tmuxinator_ground_station.bash: Script to stop all nodes launched by launch_ground_station.bash.
• stop_tmuxinator.bash: Script to stop all nodes launched by launch_as2.bash and launch_ground_station.bash.
• rosbag/record_rosbag.bash: Script to record a rosbag. Can be modified to record only the topics that are needed.
• trees*: Contains the behavior trees that can be executed. They can be selected in the aerostack2.yaml file.
• utils: Contains utils scripts for launchers.

Both python and bash scripts have a help message that can be displayed by running the script with the -h option. For example, ./launch_as2.bash -h will display the help message for the launch_as2.bash script.

Note: For knowing all parameters for each launch, you can execute the following command:

ros2 launch my_package my_launch.py -s

Also, you can see them in the default config file of the package, in the config folder. If you want to modify the default parameters, you can add the parameter to the config file.