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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  • Flashed 3.1 (from 3.0.1) to my f800 with APM 2.6

    3.1 Worked perfectly fine without any changes to tuning or compass settings.

    Today I had to test AutoTune. (I was a little nervous to try that......but)

    It also worked perfectly fine and now my RcTimer f800 Flies better than ever!!! :-) I´m So Happy!!

    Thanks for all your great work guys!

    And a a Happy New ArduCopter Year!!

  • Hi Randy,

    Does the min throttle out in recent version fixed to 1110?

    I am using wii esc firmware and it fixed to 1050-18xx. So every times I arms the copter, the motors always spin.

    Will I change the esc firmware or is there any way to configure the ACM?

    I just back to build an octa and I lost much information from 2.9 version.



  • I got to fly 3.1 on my large quad with APM 2.5. I used all the same settings from 3.0.1 and it went very well.


    I do have a couple of comments/questions:

    1. During Auto missions it yaws to the next waypoint about 10-20 meters before it hits the waypoint. I have the radius set to 2 meters (WPMAV_RADIUS = 200). It seams to me that it should not start to yaw until it enters the waypoint radius circle. Is this a bug?
    2. Also during Auto missions the yaw changes are very harsh. Is there a way to slow down the yaw acceleration during Auto missions? Also can I decrease the max yaw rate a little during missions. I think I did this on past versions but I had to change some defaults and recompile. When will 3.1 source code be available on the download page so I can decrease the AUTO_YAW_SLEW_RATE parameter?




  • Hello people

    I have a very well functioning hexa with APM 2.6 and fw 3.1rc5

    i would like to ask the experts if i install the latest fw 3.1 do i have to do compassmot calibration again?

    I have to admit that i dread that calibration because its a big hexa with MT-2820 motors and 13 inch props and i'm holding it down by hand ... it's not going anywhere with the propellers reversed but it's quite scary being so close to them at 75% throttle.

  • This is my hexa,

    All up weight is 2.6 kga

    Motors are 2836-9 950,

    Esc sk 30amps

    and I feel more power is needed , could somebody recommend me better motors for this hexa .wIll appreciate your recommendations.thanks



  • Thanks for the updated firmware, guys.  I upgraded this afternoon before taking the quad up for a shot of the sunset over the in-laws' house.  I like the update and looking forward to playing with Drift mode some more.

  • Hello,

    I was quite late so I updated my Radio 9XR with the latest firmware and my 2 chassis  TBS in 3.1 ... After redoing the inits use Radio, ESC and accelerometer ...

    Well almost all flies well ! he lost power after 30s and I do not have enough power to maintain it properly, the Trottle is background and is 1 meter from the ground and made ​​the yo-yo ....

    I thought my 3S4000 Batteries HS but were 5 at the same time frame and 2 TBS, they all two 1.6 kg with battery and have not magnified during the holidays themselves ;)....

    There must be a new parameter but I can not put my finger on SNIF!

    If you have an idea or hear the walkthrough, I am strongly taker ....

  • Hello!

    I have a problem with v.3.1 and Altitude.

    Please see the video:

    The copter is on the table, and the altitude on MP is changing all the time...

    How to solve this?


  • Merry Chrismas guys,

    i've a compass issue with firmware V 3.1 on my old (standard) APM 1.4. After compass calibrating is is never showing exactly north (compared with a magnetic compass). There is a difference of approx 15 degree. 

    However, i tried a flight in simple mode. After takeoff, i noticed a small continous yaw but the quad was stable in the air and the feeling for the trottle was really great.

    Possibly i did a mistake when calibrating in mission planner. Which compass type i shouldchoose (intern, extern, manual and which orientation)?

  • Hello,

    One question. I don't know if this is the correct post, but I have installed the v.3.1 in my case.

    The question is:

    I have 2 apm 2.6 with 433 telemetry. I only have one ground module, and I want to work with this 2 apm. (not at the same time) 

    Why not work the ground module with this 2  Air modules, if the config in this are the same?

    Sorry for my english.

This reply was deleted.


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