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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  • A few more handles on the altitude reset issue.  

    It always happens when switching from Stabilize to either alt hold or loiter.  I have never seen it happen when switching to RTL.

    Hardware is APM 2.5 with light shielded baro's.  If the altitude does not reset in flight, I usually land withtin one or two feet of initial altitude after 8-12 minutes.

    If the altitude resets, you land below zero by that same amount.

    The flight characteristics seem unaffected.


  • Hello All

    I didnt get this question answered so i thought i would ask again. 

    I just noticed in Mission Planner, on the Full parameters list, there is a drop down menu that seems to contain templates for different parameters for flight. i am interested in the Aerial photography "template". 

    What are these and do they work for any Quad/hexa/Octo? since all of my drones are camera drones, i would like to try them out, i am just wondering if they are indeed active and available for use?

    thanks in advance

    • No Answer on this? Beuller...Beuller? :P

  • Randy,

    here are three OSD recordings of the home altitude resetting in flight.  2 are from me on two different multirotors (hex and an H quad)  the other is the same problem from someone else that posted on youtube.  The remaining video is to show that this does not happen all the time.

    This has been around since at least the 3.1 release candidates and is still here in 3.1.2

    37 seconds in
    no problem
    27 seconds in
    44 seconds in

    the first video on the list above I stumbled across while loading the videos on Youtube.  Same exact issue.

    I rarely fly with my PC data link turned on.  I'll turn that on and capture a log along with the OSD recording this weekend weather permitting.

    Thanks for getting the bug looked at.


  • Developer


         If you could provide a log of that, that would be helpful thanks.

  • Hi Randy, I was just trying to do a bit of hovering to test pixhawk with my TMotor mt3506 650kv motors with propellers 14".
    After takeoff everything seems ok,and altholt is ok, but there are problems with the loiter ruth..

    With apm2.6 instead is a rock. O.o

    How so?

    here is the log




    • Are there pixhawk esc synch problems known?

      I got perfect flight with apm, changed to pixhawk and 2 crash flips with afro esc

      • I fly with 4 Afro Slim 20A no problem!

  • The code is pretty good   but I am really concerned about adding more features as opposed to cleaning up the code we have first.   Like everbody i am betting a lot on the reliability of the code.  Perhaps i am unique but would rather have that improved than add another flight mode.

    For example you can make the altitude shown by the apm reset to zero in flight by changing flight modes in a specific sequence.   

    Try this... take off in stabilize mode, fly up to say 35 feet and level off.  Switch to alt hold and watch your altitude shown on the osd reset to zero.  (It seems to happen most often if you do this within about 10 seconds.)   Note that you will land exactly -35 feet on the osd.

    I can make this repeat about one in four times.   When things like this stop happening I am ready for some new features.

  • yes it s pretty hard to know more about team and who are paid for working on it..

    but personnally i prefer to see less new features but improve all already here...we are so many features that add another should be complicated more the code so add new bugs......with pixawk generation,it s time to aim the most reliable code without release new feature.

    it s my point of view 

This reply was deleted.


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