[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:

Views: 311525

Comment by David Low on August 1, 2009 at 8:22pm
Same with you all, previously I also faced the same issue: The plane just goes to one direction regardless of RTL or waypoints until I used the "I_Can_Fly" code released by Jordi.
Nothing is changed in the source code, as for the easystar.h; what I changed is just the gps protocol (to EM406), Pitch and Roll inverse
Just let me know if you guys need any extra info to help troubleshooting :)

Comment by Jordi Muñoz on August 1, 2009 at 8:25pm
Pitch and Roll inverse..........
Comment by David Low on August 1, 2009 at 8:28pm
I used EM406 in binary protocol
Comment by Greg Fletcher on August 1, 2009 at 11:00pm
I think I may know whats going on here. You guys are still in FAKE_BEARING mode. I know you checked your easystar.h file, but was it the copy in the library? You are compiling the one in ../library/aurdupilot folder, but is that the one you are looking at and changing? Easy mistake to make if your in a hurry. Your GCS is displaying gps course and course to wp. The is steering the plane to the FAKE_BEARING ! You aren't using the easystar.h file you think you are. Maybe?
Comment by Peter Meister on August 1, 2009 at 11:09pm

Its not the fake_bearing. As I have changed it to different degree settings and it still goes north-east. I tried that many many moons ago. Now Bryan what do you mean inverse pitch and roll...?? Are you talking about reversing it, if so I do that, mine are set to 1 for both. If you are not talking about reversing those, please enlighten me on this thought a little further, and what code you are talking about :)

I am using the I_CAN_FLY and the PETER version as well. Both do the same thing, north-east...
Comment by Peter Meister on August 1, 2009 at 11:15pm
What about running it in NMEA mode. The EM406A. Jordi ?
Comment by Greg Fletcher on August 1, 2009 at 11:33pm
Read my post again. Are you changing the easystar.h file in the ......\aurdupilot2.23 folder or the one in the
Documents\Arduino\arduino-0016-win\arduino-0016\hardware\libraries\Ardupilot folder?
Comment by Bryan Cuervo on August 2, 2009 at 4:39am
If I remember right, you had one or two good flights with the I_CAN_FLY version but then you replaced your rudder servo. With the new servo, you had to reverse the rudder direction in the .h file. After this change, the plane went back to her abnormal behavior. If changing the rudder direction was the only variable altered to cause the program to misbehave, I was wondering what would happen if you changed that variable back?
But, David just reported that he is successfuly flying I_CAN_FLY with both pitch and roll reversed so that blows that theory!
Looks like our header files are identical so I'll also try the I_CAN_FLY version and see what happens.
Comment by fefenin on August 2, 2009 at 6:25am
@ Greg Fletcher,

yes of course we are changing the fake bearing settings in the right path:arduino-0016-win\arduino-0016\hardware\libraries\Ardupilot folder

i've tryied many times as Peter to delete evrything that is linked to arduino environement and there is still this strange behavior

@ everyone else
i don't have the ground station but when i put the plane on top of my car and run away following the servo moves (extension lead + aileron servo into the car of course) that leads me in the same direction far away from the bearing and distance it shows on the ground station...

are you using ailerons or rudder configuration???

i'm using ailerons (rudder stay center when autopilot occurs)

i'm sure we have to watch closer in here:

void navigation(void)
if((data_update_event&0x01)==0x01) //Verify if we have new GPS data.. Is like a flag...

data_update_event&=0xFE; //Resetting flag, 0xFE is equeal to ~0x01 (not)

float dt_t = (float)(millis()-NAV_timer)/1000.0; //Timer

if (Tx_Switch_Status()==0x01) //Check if we are in mode 2 (transmitter switch in middle position) if yes enter to waypoint mode
Set_New_Waypoint(current_wp); //Loading current waypoint.
update_distance(); //Updating the distance between the current position and the destioantion waypoints
Waypoint_Switcher(wp_distance, wp_radius); //Waypoint switcher...
else //If we are not in mode 2 please return home (waypoint 0)
//Here we put home position.
Set_New_Waypoint(0); //Waypoint zero is home.
update_distance(); //

wp_bearing=calc_bearing(lat, lon, wp_current_lat, wp_current_lon); //Calculating bearing

//Now calculates the roll set point, in order to turn to the desired heading..
roll_set_point= calc_roll(heading_error((int)DESIRED_FAKE_BEARING, ground_course),dt_t);
roll_set_point= calc_roll(heading_error((int)wp_bearing, ground_course),dt_t); //Calculate the roll set point depending the heading error.

NAV_timer=millis(); //Resetting timer

roll_set_point is corrupt but wp_distance and bear_calc seems to be ok according the ardustion
Comment by Bryan Cuervo on August 2, 2009 at 9:47am
I think you are on the right track. When fake bearing is active and you walk around with the plane, the ailerons guide you in the right direction. The navigation control system (outer loop) code appears to work but when you return to wp_bearing, the outer loop fails.


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