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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  • Developer
    I have been using a GWS 6:1 gear box with a in runner motors between 3600-4200 kva and larger prop 10x7. I trim of 13 -18mm, (balance prop) to fit also mount gear box for prop clearance. I use 1300 to 2200 11.1v lipo packs, Runs very efficiently for 20-30 min at cruise speeds. 1300 saves weight and I usually fly 5-6 mins for 3-4 flights.
  • >Jordi,
    Have you posted the header file yet that includes the CALIBRATE_SERVOS debug option? I've been looking around the site and can't find it.
  • Developer
    Thats crazy, the HIMAX alone cost 69.99999999 dlls:

    For 10 dlls you can get a Castle Creations ThunderBird 18Amp BEC, Propeller, Gold Bullets and Prop adapter:

    Note that the Thunderbird alone cost you 30 bucks:

    Anyway if somebody wants a replica of my setup now you know... (ALso Metal gear Hitec servos and 2200mhz 20-30C 3Cell Lipo)..
  • Developer
    I also use the EasyStar Power Pak! Is great! You can fly like a funjet!
  • @Earl: the 2200RPV inrunner will do just fine on the EasyStar. Check out what prop dimension and ESC max amp others are using with your battery setup.
  • I just read customer reviews for this motor. Most are using it in an EZ* and say the performance is GREAT. Looks like the one I will go with.
  • TJC,
    I found this motor HXT 2835 (380S) 2200kv Brushless Inrunner for $19. $5 shipping Is this a good deal ? 28mm dia
    I already some 25A ESC's.
  • @Thomas
    where u place the XY sensor? is it in front of esc?
    will the heat from esc affect thermal horizon sensing?
  • Admin

    Don't use the stock motor and propeller that come with the EZ* kit. I recommend that you use either a brushless inrunner or out runner motor. An inrunner is easier to mount than an outrunner, but the choice is yours.

    I purchased the Multiplex Minimag/EZ* power pack kit that comes witha Himax 2815-2000 brushless inrunner, a Castle Creation Thunderbird 18 ESC, and a MPC 5.5X4.5 propeller. I also added a 3S 2200ma LiPo to power the motor.

    I cut off the top of the EZ* motor mount and CAed in a piece of 3/4" schedule 40 PVC slip joint pipe coupler that I cut a 1/4 of the circumference off of long ways. The pipe coupler will hold the motor solidly, but you can remove it if it becomes damaged or you want to try another motor.

    I also mounted the ESC just ahead of the motor on the top side of the fuse for better cooling.

  • I'm making progress with the 223 demo code. Got the stabilization and navigation control outputs in sinc and I'm able to fly RTL and hit the first WP. Had to go into the code under the Sensor tab and make a change to get things to work with my set up. Details can be found here. Disconnecting the throttle and performing walking tests was a big help. It saved my battery, saved time and avoided the risk of crashing. I still don't really understand why the elevator trim changes during flight but maybe that won't matter once I add the AP throttle control.
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