The document outlines a workshop by Todd Stellanova on PX4 quadcopters, discussing components such as flight control boards, setup procedures, and safety measures. It details the Pixhawk project and its components, emphasizing the open-source nature of the firmware, software, and hardware designs. Additionally, it covers the calibration process, flight modes, waypoints, battery monitoring, failsafes, and advanced features for multiple drone fleets.

1. Droneflow
PX4 Quadcopter Workshop
Todd Stellanova
Founder,

2. What we’re talking about
• Options for flight control boards
• Key parts of a hackable PX4 multicopter system
• Setting up PX4 and QGroundControl
• Fine tuning and better safety
• Flight modes and automation
• Going further: firmware and hardware hacking

3. • Ardupilot/Arducopter still runs on
legacy APM 2.6x hardware,
reaching EOL
• Latest AC now also runs on
PX4 hardware
• OpenPilot runs on various boards:
• CC3D (STM32F3, no position
hold or navigation)
• Revo (STM32F4, beta
navigation)
• Others: MultiWii, Paparazzi,
VRBrain, etc.
Open Source Flight Control Boards

4. Pixhawk Project
• Pixhawk is a research project
of the Computer Vision and
Geometry Lab of ETH Zurich,
an academic institution
• Powers most of the cool
quadcopter demos you’ve
seen on TED and elsewhere
• PX4 is the autopilot hw and
sw, QGroundControl is the
ground control sw, mavlink is
the comms protocol

5. • PX4 1.x consists of a
main flight control board
(PX4FMU) and a failsafe /
IO board (PX4IO)
• “Pixhawk” is FMU+IO
combined into a single
board (PX4 2.x)
PX4FMU 1.7
PX4IO 1.3
Stacked
Pixhawk 2.4

6. Business of Open Source
• Pixhawk team does most of the hw design work (for free)
• 3DRobotics.com provides early prototypes back to Pixhawk
and iterates to fix bugs, typically releasing the first
commercial version.
• Eventually design files are released on Github. 3DR has been
known to withhold some optimizations and bug fixes.
• Some time later, boards from China and HK start appearing
on eBay and Aliexpress at half the price. YMMV
• Meanwhile, the firmware continues to iterate on Github.

7. PX4 Setup

8. (Pixhawk setup)

9. Initial setup steps
• Bind RC receiver and transmitter
• Ensure receiver outputs something the PX4
understands (PPM, S.Bus)
• Calibrate ESC and fix motor spin

10. ESC Calibration & Motors
• Ensure ESCs are calibrated to your RC receiver
• Especially important for RC passthrough for fixed
wings in case of FMU failure— unlikely you could fly
multicopter with no FMU
• Ensure motors are spinning the way you want
(clockwise or counterclockwise)

11. Motor Spin / Prop Directions

12. Setup: Firmware
• Install empty SD Card
• Connect FMU to QGroundControl via USB cable
• Flash latest FMU firmware from build server
• Reboot holding down arming switch to flash latest
PX4IO firmware
• Select airframe defaults, save and reboot

13. Sensor Calibration
• Attach power source (eg BEC)
• Attach Telemetry radio and connect to QGC
• Calibrate Gyroscope, Magnetometer (3D compass),
Accelerometer

14. RC Calibration
• Follow instructions carefully in QGC
• For flight mode switches it helps to understand the
flight modes…

15. Flight Modes
• Six main modes:
• Stabilized (manual RC)
• Seatbelt/Easy (altitude hold / position hold)
• Auto/Loiter/RTL (mission / pause / return home)
• Switch between them using flight switches

16. Flight Modes: Switching

17. Flight Modes: State Machine

18. Missions / Waypoints
• QGC and PX4 adhere to mavlink waypoint handling (as
does Arducopter, Andropilot, etc. but not OpenPilot)
• All waypoints are part of a navigation “mission”
• Missions can include takeoff and landing, YMMV
• PX4 only supports waypoints in Auto mode
• Can switch between mission and “Loiter” to pause
mission

19. Battery Monitoring
• PX4IO onboard voltage sensor warns via mavlink and
buzzer when battery is low, critical. Can configure
warning levels.
• Use battery capacity parameter if you want to estimate
time remaining
• Use a backup charge balance monitor alarm

20. Failsafes
• RC receiver probably has one (PPM, S.Bus)
• PPM defaults to “hold last before Tx loss”
• PX4FMU can detect RC loss
• PX4IO can also hold PWM levels on FMU loss. Helpful
for midair reboots.
• PX4IO manual RC passthru useful for fixed wings

21. Advanced: Tuning Sensors
and Config
• FlightPlot
• QGC Advanced
Config

22. Fleets of Drones
• mavlink supports
meshes of multiple
drones
• qgroundcontrol
supports monitoring
multiple drones
simultaneously
• but radios have limited
bandwidth

23. Going Further
• Flight control software is entirely open source:
github.com/PX4/Firmware
• Ground control software is entirely open source:
github.com/mavlink/qgroundcontrol
• Hardware design is (mostly) open source:
github.com/PX4/Hardware