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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     ..ah, thanks for catching that.  fixed!

     We're going to try out the APM Forum to see if it's better for handling support.  I'll be monitoring both in any case but the hard support stuff should probably go over there.  General chat or questions, feedback, video, etc can be here though.  It's a transitional period so let's see how it goes.

All we need now is an equivalent flight mode to the Naza GPS mode and the APM would be exceptional :)

Give Drift mode a go. I think you will find it is better....

Flying on one stick? Hmmmm not sure how that would be better.

Don't get me wrong, I absolutely love the APM and are a big spokesperson for it amongst the people I know, but... I sometimes think the APM is trying to be over-complicated. All these modes and yet the one that you would expect any flight controller to have straight out of the box, that being the equivalent of Naza GPS mode or the APM in stabilize mode but with loiter enabled with no stick input, is missing from the APM. If I knew how to program it I would give it a go but surely it can't be that hard to code for someone that does know what they are doing?

Loiter mode and Position Hold (doesnt hold altitude) is now very similar to GPS mode in Naza with this release.

But do try the drift mode. It is a new experience and if you need GPS mode this will help more.

Hi all

I know this question has probably been asked a million times, when upgrading to APM 3.1 etc. do you loose all your previous setup values, do you have to start from scratch to calibrate everything?

Maybe this can be mentioned in the 3.1 upgrade spiel.

By the way, I just got a 3DR quad and with no wind yesterday in Adelaide I did a blueprint autotune - just perfect.

Went flying today and was very responsive - have not managed to put it on its lid yet.

Without pushing too hard in testing - altitude 60m, speed 61.2km/hr



The most apparent thing to notice in the video is that Marco has a really smooth hand control of the RC Txm.

Look forward to this release. Great work all :)

@John: if you upgrade from version 2.x yes, i think you loose all the setting, if you have installed any old version 3.x no, simply upgrade your board, check the new parameters like "MOT_SPIN_ARMED" and go.
@Shyam: it's not easy to control with gloves... :-)
I use a little bit of negative expo in ALE/ELE/YAW, about 10/15%.

superb randy.. I will load the 3.1 fw version. can I use my channel 6 rx for auto tune? I only have 6 channel rx max to run apm, channel 5 for mode..

Cam, I assure you Randy and Leonard know what they're doing.  The reason why our Loiter was done the way it is now is because it is better than Naza's GPS mode.  Try making precise adjustments to the position of your quad in a high wind with Naza, and then you will see.

No, only with CH7/8 i think, use a 6 channel rx with APM Copter is a bit restrictive.

Hi Randy, One of my hexa's has a hard to reach USB port....requires some diassembly, I am running 3.1RC8.  Is there any reason why I need to move to 3.1? I do not have any issues after about 9 flights.  I know there was the RTL issue, but I never saw it due to my speed settings.  Pls let me know and thanks for a great release, JEFF

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