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.

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  • Developer

    I am pleased to present the new "Hybrid flight mode" for APM Copter boards, a "flyable position hold" similar to the same flight mode of DJI, Mikrokopter, Zero-UAV etc... stay tuned! :-)

    Bests, Marco

  • Problem with vertical speed on a large Hexa.

    happy new year to every one ,and congratulations to the all team who worked on the last soft version 3.1.

    Everything works great (stab ,alt hold,loiter,RTL) the only problem is manual landing : reducing gas to land is very touchy and it looks like even in the low part of the gas stick the motors are running too fast !! I have reduce throttle accel P to 0.5, I to 1.0

    and Throttle rate to P 3.5 it is better like this but still difficult to achieve a nice and proper landing.

    Any suggestion for tuning it properly ? Marco pls??

    I had to adjust Throttle MId to 330 to get hovering at  middle stick

    Config :Hexa Tarot 690 ,motors T-motor 4006-13 KV740,Props carbon 13x4,Lipo 4S total weight around 2.2kg with gimbal

  • Developer

    ArduCopter-3.1.1-rc1 is now available through the Mission Planner's Beta firmwares link.  It's really a patch release mostly for Pixhawk users who had run into some SD card reliability issues.

    There are very few changes for APM2 users but includes fixes for Warning #5 (Loiter init bug) mentioned above and fixes an annoying issue when loading ROI commands from the APM.

    If there aren't any significant issues we will make this the official version in about a week.

    Thanks and all feedback welcome!

    Changes from 3.1
    1) Pixhawk improvements:
        a) Telemetry port 2 enabled (for MinimOSD)
        b) SD card reliability improvements
        c) parameters moved to FRAM
        d) faster parameter loading via USB
        e) Futaba SBUS receiver support
    2) Bug fixes:
        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:
        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

    • Hi Randy, 
      do you know how I can take this ArduCopter-3.1.1-rc1 (or another version, preferrably 3.1-rc5) edit the code (add some flightmodes etc) and build this for my pixhawk? 
      I would be so thankfull if you could help me with this!


  • Hi All,

    I have run into problems and need some help to understand. I have two copters, a Hexa and an Octo. Both upgraded to the official 3.1 and I have done the Autotune without problems. I have no cameras onboard until I feel safe with the behavior. The copters became very crisp in their behavior and they have lots of power. I flew a simple Auto mode with two waypoints and automatic landing with the Hexa. Just perfect. Then I added a circle command after the first waypoint. The copter got wild just before the first waypoint followed by a crash. Low vibration level and no wind.

    A couple of days later I tried my Octo. After Autotune, a perfect two waypoint flight. I inserted a circle after the first waypoint, the same thing happened just before reaching the first waypoint. No wind and good enough vibration level. This time I was more alert and switched over to loiter, alt hold and stabilized and succeeded to save the copter after some wild maneuvers.

    3692919985?profile=originalSome thoughts about what could have caused the problem.

    • The PID loops are too close to self oscillation after the AutoTune. They were set much more aggressive than what I used earlier.
    • The APM is too slow in calculating the control loop, as I am collecting too much data.
    • Transition problem in the Circle command
    • I have seen similar behavior when hitting the fence, very aggressive

    After the incidents I have reduced the roll/pitch (50%) Rate P and I.  Reduced Yaw P from 4,5 to 2 and the data collection to default.

    Now the problem is confirmed with several flights with and without Circle command. It seems that the Circle command takes over before slowing down and reaching waypoint #1 and pull full speed towards Circle waypoint and at the same time full yaw. See the added video. Still very aggressive although lowered gains. I will skip the Circle command and wait for a solution.

    Circle command problem

    Please let me know if someone else has experienced the same behavior and thanks for all work you all have done to make it possible for me to fly.


    Frame   Foxtech foldable FH H800
    Prop       RCtimer carbon 12x3.8
    Motor    Tmotor 3506-25
    ESC          RCtimer 20A     High timing
    APM 2.5                 3.1 official firmware
    Battery                   4s 9 Ah Lipo
    Weight                   2630 g
    Radio     Spectrum DX8

    Frame   Foxtech Octo FH-H800
    Prop       APC  12x3.8
    Motor    Tmotor 3506-25
    ESC          Hobbywing Flyfun 30A     High timing
    APM        2.0   3.1 official firmware
    Battery                   4s 9 Ah Lipo
    Weight                   2930 g
    Radio     Spectrum DX8

    2013-12-20 09-55.log.gpx

    2013-12-20 09-55.kmz

    2013-12-20 09-55 hexa crash.log

  • Just out of curiosity, using 3.1 and when the APM is connected to MP what voltage should be displayed in the HUD.

  • Sorry if this has been answered previously.  I have been searching for a list of flight modes (Stabalize, Loter, etc.) and their PWM values.  Is there a table somewhere?





  • greate improvements.

    test autotune on my qav400 quad. 

    roll p need to manually increase a bit. pitch ok.

  • Moderator

    Re Arducopter, from what version will it be for Pixhawk only and no longer be for APM? i.e. Is there still a version or two planned or how close is APM to the end of the road?

  • This has Pixhawk support.

    I guess you can load AC3.1 on the pixhawk using MP.  

    Can you load AC3.1 using QGCS?

    Will QGCS work with trad helis?

This reply was deleted.


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