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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Ok I think GPS (Loiter mode) makes my H4 approach ground at sub optimal angle and speed.

Happened on -rcX  October 31 (rainy afternoon) and again today when filming icing.

Arducopter 3.1
Stab mode and Alt Hold were just fine.
The moment I switch to Loiter mode copter flies forward and hits tree branches. Then it flies in the opposite direction and touches the wall.  Crash landing. Will need to replace 2 carbon props due to tips become shorter.  Minute after that crash I had it up in the air and filmed it all in stab mode.  Do not trust that GPS.  GPS track was weird when I tick "show map" in log browser.   May be with that water on the trees GPS signal was not strong enough?

Looking for advice to get that GPS stop crashing copter.


sorry for your crash.

First time loiter with 3.1 and 5010 620kv motors.. thx

gps сигнал не то что плохой он ужасен))) в момент улёта спутников всего 5 hdop больше 4 это очень плохо

перед запуском надо было подождать минут 5 чтоб поймал нормальный сигнал

  Did anybody try v3.1 in APM1  ?


Im using v3.1 on my APM1 board.  I had to disable a few features to get it onto the board though.  So far I've tuned my thr_accel_p to hold altitude nicely and now Im waiting for a calm weekend to do autotune...


gps speak badly hooked, very bad

Hi Andre:

  Thank you for the information, I will try from  GitHub   .

Waiting for your good news.

Thanks Юрий.   I would say with HDOP > 2.5 ignore GPS.... and do not crash into houses.

I do not think HDOP is displayed on the MP main screen.   It would help to have it in OSD (via Mavlink) and on MP screen.

I let Randy comment on inertial position hold in lioter.  Should that be preventing such fly aways when GPS signal is weak and reported pos jumps around?

HDOP is shown on the MP main screen, bottom left of the map.

still seeing 3.0.1 firmware. but I loaded wot was 3.0.1 and I guess it loaded 3.1 coz I got the warning about motors turn slow when armed but I cant see the MOT_SPIN to change it. so tested and motors don't turn so I don't know which firmware im using.


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.

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