3D Robotics

ArduPilot (Legacy) main page

 

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[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).


Resources:

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:

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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.

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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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Comments

  • 3D Robotics
    Nigel, we'll certainly try to do the first. The second is tougher, but do listen to this week's podcast when it's released later today, as we discuss just this subject.
  • When 2.5 is released will it be possible to get a list of changes (added features, bug fixes)? Also, to help those of us who make changes to the software (eg to print out different variables for telemetry/debugging), is it possible to have some sort of roadmap of future planned releases/functionality enhancements or hardware dependencies?
    Thanks
  • Developer
    I mean nice spot! ;-)
  • Developer
    Opps sorry! Nice sport Automatik!! please erase the first highlighted line... All this will be gone in V2.5.

    /****************************************************************
    * This function calculate the desired roll angle...
    ****************************************************************/
    int calc_roll(float error,float dt)
    {
    static float I;
    static float D;
    static float previous_error;

    //Integratior part
    I+= (float)error*dt; //1000 microseconds / 1000 = 1 millisecond
    I= constrain(I,-10,10); //Limits
    I=reset(I);
    //error=(error*head_P)+(I*head_I); <--Erase!!

    //Derivation part
    D=(error-previous_error)/dt;
    previous_error=error;

    error=(error*head_P)+(I*head_I)+(D*head_D);

    return constrain(error,head_error_min,head_error_max); //Limiting the roll....
    }
  • 3D Robotics
    We've redone that section in the 2.5 code, which will be in beta in about a week.
  • I took a look at ArduPilot code v2.4 and in examining some roll stuff I cam across following calculations for PID error. Looking at Integrator part of calculation- see first bold line - I can see how error is calculated. Also, note that derivative is not used ( head_D is set to 0 in easystar.h file (from file: #define head_D 0 //Derivative not used, but someday...). So few lines later error is calculated again - see second bold line. So it looks like error is recalculated again...If we really don't want derivative then I think that whole derivative section should be commented out, and that output of this subroutine should be first bold line .

    Is this really the case of just forgetting to comment-out some lines, or calculation is proper (if so why, as I don't get why error is recomputed)?

    In \ArduPilot_EasyStar_V24\Control.pde

    /****************************************************************
    * This function calculate the desired roll angle...
    ****************************************************************/
    int calc_roll(float error,float dt)
    {
    static float I;
    static float D;
    static float previous_error;

    //Integratior part
    I+= (float)error*dt; //1000 microseconds / 1000 = 1 millisecond
    I= constrain(I,-10,10); //Limits
    I=reset(I);
    error=(error*head_P)+(I*head_I);

    //Derivation part
    D=(error-previous_error)/dt;
    previous_error=error;

    error=(error*head_P)+(I*head_I)+(D*head_D);

    return constrain(error,head_error_min,head_error_max); //Limiting the roll....
    }
  • Any update on when 2.4.6 will be available?
  • Must have Chris, but the unit has nor been out of the lab. I re did it and put hold altitude to 6700 ft and now ArduStation reeds correctly.
    Thanks
    Earl
  • 3D Robotics
    Earl,

    The config utility reads the home altitude from the EEPROM after a bind-plug calibration. It is possible you last did that process at a lower altitude?
  • I think I found part of the problem. All the waypointa and Home position read about 5100 feet. That is not correct. The correct altitude is about 6590 feet.
    Is the configuration program using the wrong datum maybe ?
    Earl
This reply was deleted.