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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Alex, i believe they send you a power module in the kit as stated on the purchase page

I see it now. That means what I was told is correct: they aren't compatible which is understandable. Power needs for Pixhawk might very well be different than APM 2.5&2.6

APM will still be a great autopilot for small to midsize multicopters (up to hexa I would say). For Octo and larger multicopters, Pixhawk will sure be a better route...

Alex i am pretty sure that is the same Power Module as the APM 2.6, as it is listed it says 3DR power Module with ATX 60. i have 3 APM 2.6 boards, and all use that one, i dont see anyone specifically designed for the PixHawk on the 3DR site.

Yes, Thor is correct.  The PM is the same as the one on the APM2.6.

What I've heard is that because the Pixhawk is only 3.3V while the APM2 is 5V, using this same PM means that the Pixhawk can only read the current up to 60amps (the APM using the same PM could read up to 90amps).  It's not dangerous, nothing will blow up but it ends up reading a smaller range.  Most copters hover somewhere around 25amps so it's not terrible.  I hear 3DR will be making a few different power modules in the future including ones that can monitor much higher currents (and voltages) whether you're using an APM2 or Pixhawk.

 Seems to me from what Randy said its another thing that could be a problem. Ya ya I know "its not a problem" now. You develop a whole new controller why not finish the job and not use band-aids or it will get us buy sort of deal till we put out a new one later.  If I was going to the trouble and expense to switch out to a Pixhawk or use it on a new build I would want a better module but hey that's just me.

Thanks Thor, Randy. It just makes it better with the same PM.

Randy, if pixhawk is 3.3V, will users fry it if they try and power it from the output rails at 5-5.5v?

It's what I was going to do, as my rigs are 6S and don't use a PM.


     No, it should be ok.  The power supply is much more sophisticated on the Pixhawk (as compared with the APM2) so it'll draw power from either the power module or whatever's supplied through the output rails.  It's mentioned at the bottom of this page.  If you have both a power module and plug in the external BEC then it'll use the power module unless it drops below 4V at which point it will switch to the output rail.

     I'm not sure what is the max voltage that can be fed into the Pixhawk's output rail but I think it's even higher than 5V.

Ahah! So it does. Cool - looks like it's a straight swap in for me. Cheers Randy.

Another query - The safety switch - is it really that big? I've no idea how I'm going to mount that...

Require an hole, 8 mm, but it can be fixed in another way.

In this image a prototype of the new "APM Power Module 2.0" in my hands (thanks Craig), which supports high amperage and over 6S LiPo, i think will be released to the market in Q1 2014.
Being just a prototype doesn't have the appropriate power connectors, and there is obviously the possibility that the final version is completely different.
This is the only witness who 3DRobotics is also working on this, useful if you want to install like me the Pixhawk on a big multirotor with double LiPo pack at high amperage/voltage.

Nice!!  I'm jealous.

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