PX4 Autopilot Extended to Fully-Actuated Multirotors
This is the repository for the PX4 autopilot with the enhanced ability to work with fully-actuated robots. It is based on the original PX4 firmware (current version branched from master on Jan 21, 2020) and supports all the functionality and airframes of the original PX4 in the same way. However, it additionally provides implementations of attitude strategies for fully-actuated multorotors that allow the 6-DoF flight. It includes the definitions for a hexarotor with all rotors tilted sideways and has been tested on several UAVs.
For more information and to access the publications, please visit the AirLab's website.
To access the original PX4 autopilot repository and website, please visit here and here.
Installation
For general PX4 functionality, please visit PX4 User Guide and PX4 Developer Guide.
To be able to compile the firmware, you need to first setup your system and install the toolchain.
If you are not planning to use the firmware with ROS (the case for all AirLab use) and our ROS packages, you can go directly to the next step (cloning). Otherwise, make sure you are using Ubuntu 18.04 with ROS Melodic and go to the src folder of your catkin workspace before cloning. If there is no catkin workspace, you can create a catkin workspace and go to the src directory with the following command:
mkdir -p catkin_ws/src
cd catkin_ws/src
Now clone this repository and all its submodules:
git clone https://github.com/castacks/PX4-fully-actuated.git Firmware --recursive
Test that everything works fine using the guide on this page.
You can skip the rest of this section if you are not using the autopilot with AirLab's ROS packages. Otherwise make sure to follow all the following steps.
Add the environment variable PX4PATH to your .bashrc file to get global access to the path. For example, if you have used the catkin_ws workspace created above, you can do this:
echo 'export PX4PATH=$HOME/catkin_ws/src/Firmware' >> ~/.bashrc
Now make sure you properly set the Gazebo path to the one in this repo. Add the following to the end of your .bashrc file:
source /usr/share/gazebo/setup.sh
export ROS_PACKAGE_PATH=$ROS_PACKAGE_PATH:$PX4PATH:$PX4PATH/Tools/sitl_gazebo
export GAZEBO_PLUGIN_PATH=$PX4PATH/build/px4_sitl_default/build_gazebo:$GAZEBO_PLUGIN_PATH
export GAZEBO_MODEL_PATH=$PX4PATH/Tools/sitl_gazebo/models:$GAZEBO_MODEL_PATH
export GAZEBO_RESOURCE_PATH=$PX4PATH/Tools/sitl_gazebo/worlds:$GAZEBO_RESOURCE_PATH
How to use
The current tilted-hex airframe is defined to have 30 degrees of side tilt, similar to what is described in our papers. To change the geometry for your airframe, you can modify the definition of the tilted hex or add your own definition. To add the new definition file, please consult the PX4 guides above. To modify our airframe, you can find it here.
After compiling the firmware and uploading it on your hardware (see here), choose Hexarotor x with tilted arms airframe. This firmware also adds a set of parameters all starting with OMNI_. To see the description of the parameters, please refer here. The most important parameter is OMNI_ATT_MODE which supports the attitude strategies.
We have tested the firmware only with Pixracer. If you have flash memory issues when compiling for your hardware, one solution is to comment out the geometries that you don't need in this CMakeLists file.
Simulation and more
More detailed guide will be incrementally added here. Please reach us directly or submit an issue on this repository if you have specific questions, concerns, feedback or bug reports.
To simulate using Gazebo, you can run the SITL simulation of our UAV using the following command (needs to be executed from the Firmware folder):
make px4_sitl gazebo_hexa_x_tilt
Related Packages
A ROS Interface package for this fully-actuated UAV firmware can be accessed from https://bitbucket.org/castacks/core_px4_interface/src/contact-inspection/.
Our ROS position controller which uses this interface to control the fully-actuated robot can be accessed from https://bitbucket.org/castacks/core_pose_controller/src/contact-inspection.
Disclaimer
Note that changing any of the parameters (e.g., the attitude modes) will affect the flight behavior of the UAV mid-flight.
Finally, we are still in the testing/development phase and the code is in no way fully tested or complete. Use the code at your own risk and please report any bugs or issues to help us make the firmware more useful for the users.
Acknowledgment
In the initial commits, the idea of how to extend PX4 to support 3-D thrust and fully-actuated vehicles have been taken from here.
Contact
Azarakhsh Keipour (keipour@gmail.com)