Hi reader, this PX4 version is related to the master thesis work "PX4 autopilot customization for non standard gimbal and UWB peripherals" developed by Francesco Malacarne and supervised by Simone Silvestro, Marcello Chiaberge and Gianluca Dara. The goal was to implement a single axis gimbal on a ultralight drone (equipped with Pixracer) and to develop a custom driver for UWB modules (DWM1001-dev) to be used for future indoor navigation applications currently under study at PIC4SeR. While the first part was intended to work only for Pixracer-based systems, the second one should work with any configuration without significant changes (Pixracer and Pixhawk in particular).
The stabilization module is named servo_control. Its working principle can be broken down in the following steps: it subscribes to the attitude topic, it extracts the drone pitch and it creates a counteraction to be published on the pin where the servomotor is connected. In parallel, it takes the radio controller input and it adds it to the stabilization contribution. In the end, the sum of the two components is published on actuator_control_3 topic, so that the servomotor connected to PIN 5 can be driven accordingly.
The final result is a stabilization effect inversely proportional to the drone pitch, where the zero-offset stabilization point can be chosen by the operator using the RC.
The serial driver is named dwm1001. Its working principle can be broken down in the following steps: it opens the serial port (TELEM2 by default), it programs the UWB module with command "lec" and it starts reading the message over the opened serial port. Then, it sorts the information out and it publishes them on a new topic named dwm1001 according to the following structure:
- Distances between the i-th anchor and the tag to be located
- Estimated position (relevant value for indoor navigation)
- Number of detected anchors
- Estimated position indicator for debugging purposes
The final result is a driver able to read information coming from the sensor and publishing them on a new topic.
- Fork this repository into a directory that you know using the following command:
git clone https://github.com/francimala/Firmware.git --recursive
- Open a new terminal and go into the directory where you downloaded the code.
- Plug Pixracer flight controller and build the code using:
make px4_fmu-v4_default upload
- The stabilization module servo_control will start automatically, whereas the driver should be initialized manually.
- Before initializing the driver it is recommended to start the logger so that dwm1001 messages will be all saved into the microSD card. Initialize the logger using logger on into the MAVLink console. If you forget it, don't worry, the logger will automatically start when the drone is armed, nevertheless you will lose some data.
- Initialize the driver using dwm1001 start in MAVLink console. The driver is correctly started if you read the message "Got the beginning" on the serial port.
- When the flight mission is over, you can read the log file accessing the microSD log directory. For the conversion use pyulog (https://github.com/PX4/pyulog). Copy the correct .ulg file in a directory you know and run the command ulog2csv ulog file.ulg in a new terminal. This procedure will create a csv human-friently document in that folder containing all the logs.
- Stabilization module can be found in directory: Firmware/src/modules/servo_control.
- DWM1001 driver can be found in directory: Firmware/src/drivers/distance_sensor/dwm1001
- rc_update has been slightly modified, it publishes on a different topic (actuator_control_rc instead of actuator_control). It can be found in directory: Firmware/src/modules/rc_update
- mission_block.cpp was slightly modified to support 1-axis gimbal. It can be found in directory: Firmware/src/modules/navigator
It is highly suggested to fork this firmware and to build it as is because I had to make small changes to some CMake files to let the firmware integrate the new modules that I created.
- PX4 Developer guide: https://dev.px4.io/master/en/
- PX4 User guide: https://docs.px4.io/master/en/
- PX4 Doxygen: https://px4.github.io/Firmware-Doxygen/dc/d61/md_src_drivers_uavcan_uavcan_drivers_stm32__r_e_a_d_m_e.html
- Connection between Arduino and DWM1001-dev module: https://github.com/francimala/Arduino-MEGA-to-DWM1001
- Servo stabilization module explanation (italian): https://youtu.be/IgG5OOK1Tyw
- Driver explanation (italian): https://youtu.be/0GsJtd7PwT8
- How to manually integrate these customization (italian): https://youtu.be/V-wbH9gnAvw
- How mixing works: https://www.youtube.com/watch?v=N97bxWtoPJ8&ab_channel=FrancescoMalacarne
- UWB testing: https://www.youtube.com/watch?v=FuytZULFfAo&ab_channel=FrancescoMalacarne