ArduCopter-3.1 released!

After months of testing AC3.1 is finally available in the Mission Planner and GitHub.

Warning #1: If the vehicle is left landed (but armed) while in AltHold or Loiter mode for more than a few seconds, the vehicle may suddenly jump into the air the moment the pilot raises the throttle above zero.  The reason is the baro altitude may fall while the vehicle is sitting on the ground.  In AC3.2 this bug is fixed because we reset the target before take-off.

Warning #2: Motors will spin (slowly) by default as soon as the copter is armed!  You can switch this feature off by setting the MOT_SPIN_ARMED parameter to zero.

Warning #3: if you see "Bad Gyro" on the HUD then you may have a blown 3.3V regulator.  See this thread for details.

Warning #4: if you use a sonar set the SONAR_GAIN parameter to 0.8 or lower

Warning #5: Trad Heli users should now connect their main rotor ESC to APM's RC8 output

Warning #6: Trad Heli BUG causes loss of collective control in ACRO mode if swash type set to flybarred (i.e. not flybarless).  Will be fixed in AC3.2.


The major improvements over AC3.0.1 are (full list here):

1. Pixhawk support (Tridge & PX4 development team)

2. Autotune of Roll and Pitch gains (Leonard/Randy)

3. Drift mode (Jason)

4. Improved Acro (Rob/Leonard) and new Sport mode (Leonard)

5. Arming, Take-off, Land in Loiter or AltHold

6. TradHeli improvements (Rob) including:

a) support for direct drive tail rotors

b) smoother ramp-up of main rotor

c) reduced collective for better control in stabilize mode (STAB_COL_MIN, STAB_COL_MAX params)

7. Support for SingleCopter (Bill King)

8. Performance improvements resolve AltHold troubles for Hexa & Octacopters

9. Safety Improvements:

a) GPS Glitch detection (Randy)

b) Motors spin when armed (Jonathan Challinger)

c) crash detector shuts off motors if copter flipped for 2secs

d) batt failsafe option to RTL instead of LAND, gps failsafe option to trigger AltHold instead of Land

e) more pre-arm checks of inertial nav speed,

10. Bug fixes:

a) optical flow working again (although performance is still not great because not integrated with inertial navigation)

b) ROI working (use DO_SET_ROI command)


How to upgrade:
Click on the MissionPlanner's Initial Setup >> Install Firmware screen.  The version numbers should appear as "ArduCopter-3.1", then click the appropriate frame icon and it should upgrade as per usual.

Special thanks to Marco and the many beta testers on the AC3.0.1 thread who put their copters at risk during the testing of this new version and uncovered many problems so that you don't have to!  Here are some of their videos: loiter in wind, patio sonar, autotune, autotune2, roi, beach, acro, vrbrain, tricopter, train spotting, radio failsafe, the tree, double loiter


If you haven't seen it recently, please check out the ArduCopter wiki.


Feel free to post comments below and we're going to use the new APM Forum for support issues so please post your support requests there.

You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –


  • I've just posted my APM1 Autotune results over on the new APM Forum if anyone is able to browse through them and comment -


  • Developer

    AC3.1.1 has just been released and should show up in the mission planner within an hour.  There are no changes vs -rc2 but as a recap here are the changes vs AC3.1:
    1) Pixhawk improvements:
        a) Faster arming
        b) AHRS_TRIM fix - reduces movement in loiter when yawing
        c) AUX Out 5 & 6 turned into general purpose I/O pins
        d) Three more relays added (relays are pins that can be set to 0V or 5V)
        e) do-set-servo fix to allow servos to be controlled from ground station
        f) Motorsync CLI test
        g) PX4 parameters moved from SD card to eeprom
        h) additional pre-arm checks for baro & inertial nav altitude and lean angle
        i) Telemetry port 2 enabled (for MinimOSD)
        j) SD card reliability improvements
        k) parameters moved to FRAM
        l) faster parameter loading via USB
        m) Futaba SBUS receiver support
    2) Bug fixes (for both APM2, Pixhawk):
        a) Loiter initialisation fix (Loiter would act like AltHold until flight mode switch changed position)
        b) ROI commands were not returning Lat, Lon, Alt to mission planner when mission was loaded from APM
    3) TradHeli only fixes (for both APM2, Pixhawk):
        a) Drift now uses same (reduced) collective range as stabilize mode
        b) AutoTune disabled (for tradheli only)
        c) Landing collective (smaller than normal collective) used whenever copter is not moving

    Some of the "Pixhawk improvements" like "Faster Arming" will be release for the APM2.x as part of the next release, AC3.2.

    The reason the versions are slightly different between the APM2 and Pixhawk is not that we're giving preferential treat to the Pixhawk.  It's because it was impossible to release the Pixhawk hardware related fixes (like "SD card reliability improvements") without also including some of the functional improvements.  I didn't want to include these functional improvements for the APM2 because that would have invalidated all the testing we did for AC3.1 and I know there are some issues that would make people unhappy (like this one!)

  • Developer

    By the way, sorry that I haven't been able to do as much log analysis recently.  The issue is that there's just so much demand for log analysis that if I try to do it all I can't make any progress on the development side and that'll seriously delay the implementation of the vast number of enhancements requests.  I think we've dug up a few people that are willing to pick up some of the support load and at least one other who is looking at some automatic log analysis tools so hopefully that together will help answer some of the demand.

    • Hi Randy,

      I think that if there was a place where all the details about logs were held, (what kind of stuff is in there, what it means etc) there would be fewer people asking for help with analysis, i may have missed it if there is such a repository already, 



  • Hello everyone and Helllllllllllppppp me !!!!!,

    On both my quad , I have installed version 3.1 and they are very "soft" power , I increased the value trottle_max to 2000 to find a slightly correct reactivity , but it is not viable , it also has a derivative in yaw to the right, if I change the yaw , it loses enormously altitude.If I go back in v3.0.1 , no problem after the initialization and calibration .. Of course whenever a reset and erase . the frame are two TBS , same ESC and the motors.
    I continue to test the beta version 3.1 on one . but I can not seem to eliminate the problem of power, which does not occur until version 3.0.1 .
    I even tried on Y6 which does not have the same ESC / motors and I have exactly the same problem of power, and reaction to the change on the Yaw .

    Is there a particular parametrage for power 3.1 because , I absolutely do not understand what is happening . I tried full version but the problem appears systematically with version 3.1 and supp .

    thank you very much in advance for any help you could give me


  • can autotune be done with using only sonar to lock alt hold and without using the GPS to lock height and position?

  • On the Morning, I just flight it and observe have drift out position a little bit is about 2 m. I see HDOP on Mission Planner have climb up and Down is 1.7 - 2.5 (sometime over 3.5). I believe GPS Glitch Protection is still working for don't Fly away.

    GPSGLITCH_ACCEL  300 cm^s^s


  • Hi, me again...  Until asking some help for my AltHold issue.  I loaded 3 different firmwares and the behavior is the same, so this is not a bug (like you should already know) in the 3.1. Now I'm with 3.0.1 , raised the THR_MID from 500 to 600 and I got a little better result in ALt Hold mode, but still with some random erratic "jumps" in altitude.  I'll try to low the ACCEL_P value a little bit to try better results, but I don't know what more to do.  Any advice from experts?

    How you can see in the attached images and log from my last flight, the vibrations are under control. 

    Hoping some help, thanks again!

    3.0.1 Vibrations.jpg

    2014-01-24 17-11 10.log

  • Nice video Balloon, really looking forward to the Hybrid update when that comes out.

    I have been flying 3.1 since that come out and very happy with the Hex, especially after auto tune and playing around with them to suit my preference, I couldn't be happier.

    But I think it's time to move onto the beta firmware version and give that a go, one must keep pace with technology and share some of the responsibility of having a go.

    Marco, just a quick question, has the testing been going to plan with the latest version?


  • I have invite from Marco for test New mode is Hybrid for test my Quad. And, This is Alpha Firmware. After test about 6 flight and tune new parameter for my quad. I have feel on control is same DJI with GPS mode and no have weave when move and brake on the air. It no different DJI or MK. I hope it have this's mode in Next Release Firmware.

This reply was deleted.


Shivchand Jaysaval liked Shivchand Jaysaval's profile
Aug 25