3D Robotics

ArduPilot (Legacy) main page




[This original ArduPilot board, now called the "Legacy ArduPilot" is no longer produced or officially supported by the DIY Drones dev team, and this page is maintained just for historic reasons. However, there are still many users of it out there and it still works fine. The user group for Legacy ArduPilot users, for both thermopile and IMU use, is here.]


ArduPilot is a full-featured autopilot based on the Arduino open-source hardware platform. It uses infrared (thermopile) sensors or an IMU for stabilization and GPS for navigation. It is the autopilot used to win the 2009 Sparkfun Autonomous Vehicle Competition.

The hardware is available from Sparkfun for $24.95. An expansion board ("Shield") kits that includes an airspeed sensor, a 3.3v power regulator for 3.3v GPS modules and other sensors and cables and connectors for easy attachment of the XY and Z sensors, is available from our own store for $57.20.


User f

ArduPilot features include:

  • Can be used for an autonomous aircraft, car or boat.
  • Built-in hardware failsafe that uses a separate circuit (multiplexer chip and ATTiny processor) to transfer control from the RC system to the autopilot and back again. Includes ability to reboot the main processor in mid-flight.
  • Multiple 3D waypoints (limited only by memory)
  • Altitude controlled with the elevator and throttle
  • Comes with a 6-pin GPS connector for the 4Hz uBlox5 or 1hz EM406 GPS modules.
  • Has six spare analog inputs (with ADC on each) and six spare digital input/outputs to add additional sensors
  • Supports addition of wireless modules for real-time telemetry
  • Based on a 16MhZ Atmega328 processor. Total onboard processing power aprox 24 MIPS.
  • Very small: 30mm x 47mm
  • Can be powered by either the RC receiver or a separate battery
  • Four RC-in channels (plus the autopilot on/off channel) can be processed by the autopilot. Autopilot can also control four channels out.
  • LEDs for power, failsafe (on/off), status and GPS (satellite lock).


ArduPilot requires the free Arduino IDE to edit and upload the code to the ArduPilot board.

The code is currently optimized for the Mutiplex EasyStar three-channel powered glider and FMA sensors, but can be modified for other aircraft and sensors. It uses the rudder/ailerons and elevator to maintain level flight and navigate to GPS waypoints. It supports a desktop setup utility and ground station software. It also includes a "fly-by-wire" mode that simply stabilizes RC flight. The main code is ArduPilot2.x.zip in the download section of our Google Code repository, where x is the latest version.

What you need to make a fully-functional autopilot:

Open source extras:

  • If you want to build your own board from scratch, the necessary files and component lists are here.
  • [Note: you shouldn't need this, since this code is loaded on the ArduPilot board at the factory] Latest multiplexer code (for the board's second processor, an Attiny, which runs the failsafe system) is here.
    Instructions for loading this code are here.

Recommended UAV setup:


Airframe option one: Hobbico SuperStar (49" wingspan, $95, shown above). This is an inexpensive, good flying high-wing trainer with ailerons. It can be hand launched in a park or take off from a runway, and replacement parts are readily available in case of a crash. If you want much better performance with this aircraft, you can upgrade it to a brushless motor, speed controller and a LiPo battery. [If you don't already have one, you'll also need a balancing charger and power supply.] Note: any stable aircraft with both ailerons (for stabilization) and rudder (for navigation) can work, so feel free to experiment with what you've got.


Airframe option two (recommended for ArduPilot 2.x): EasyStar (shown above). Performance can be improved with the modifications described in this post.

You'll also need:

  • A six or seven channel RC transmitter and receiver, with at least one toggle switch (ideally three-position but two-position will work, too, although you will have to mix channels to have access to both autopilot modes in the air), such as the Futaba 7C.
  • Some servos (at least three for ArduPilot 1.0; at least two for ArduPilot 2.x) and at least three female-to-female servo cables to connect the RC receiver to ArduPilot.

Cool optional extras for your UAV:

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  • field test June 6 2010 b.TXT

    Had a good test flight with 2.6 firmware. Here's the flight log. Stabilization worked great but Fly_by_wire gave me some drift. There some wind.

    Do I need to adjust anything before trying the full AUTO mode?

    PS> I'm using just XY sensor with no shield
  • Developer
    I just finished flying the latest update on 2.6. This update should solve any failsafe issues.

    Throttle Failsafe is now user selectable.
    There is also a new CH3_TRIM value of 0 which means trim the throttle at startup. Any PWM value will skip reading the throttle trim at startup and use that value instead. Mine is 1100, which I found out by reading the serial header at startup.

    Throttle failsafe will not kick in during manual mode. Good for preventing accidents on the ground.

    I found an issue with reverse throttle. I don't know anyone who flies this setup so it never came up as a bug. If you do, please verify the fix works for you.

    I added more granularity to the events.pde tab which should let you have more detailed control for the throttle failsafe.

    You can try it out by downloading the latest from the SVN repository. You will need to update your header file and copy over any changes you made.
  • Assan 2.4 GHz sorry...
  • RX is Assan GHz with built in failsafe.
    Actually, this is a problem in case of radio loss, the RX will go into failsafe and will trick the Ardupilot failsafe into thinking the radio is transmitting don't you think?
  • ok, thanks :)
    Does this apply to ailerons throw as well?

  • 3D Robotics

    I think your problem is due to a low-voltage radio triggering the failsafe; please wait a day or two for us to sort that out.
  • xyz by the way
  • I'm using Thermopiles from CoPilot
  • Developer
    check out FieldSetup It mentions it. I clarified the language a bit to match the current behavior in 2.6.
  • 3D Robotics

    Are you using the IMU or thermopiles? As for the throttle thing, I suspect that's due to a misconfigured failsafe. We're going to turn failsafe to off in the next version of the code, which we'll release next week.
This reply was deleted.