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.

You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –


                • Joe, did you get any logs?  

                  I see that you've managed to fly 3.1.2 and find that it is OK.  If you could get some logs of the problem that would be good to help us figure out what it could be.  As it stands now, there's been no changes to 3.1.2 that would affect Loiter, so it's very odd that 3.1.2 would fix a problem with 3.1.1.

          • GPS and INAV, ATT, and probably CTUN and NTUN.

            Problem is... you might not get any logs in Loiter from an Octo.  You might need to test on the quad.  You can try the Octo, but it really depends on what features you have running.  I can't remember exactly where the breakpoint is.

  • Surprising Marco.
    In Parameters.h i find "k_param_rc_feel_rp, / / 40".

    After flashing, I got   RC_FEEL_RP = 100.


    • Developer

      Ok, so the eeprom location is 40 but actually the default value is 100.  That's only available on the Pixhawk.  It'll be out on the APM2 when AC3.2 goes out.  It just filters the roll-in and pitch-in while in stabilize, althold and drift flight modes.  If you go to the MP's Flight Data screen, press Ctrl-F then push the paramgen button, then restart the MP then in the Advanced Params list you'll find the 5 available settings for it from Very Soft to Very Crisp.  Alternatively you can just set the parameter's number manually through the full parameter list.   0=Very Soft, 25=Soft, 50=Medium, 75=Crisp, 100=Very Crisp.


      • Have to say the Soft mode feels exactly like Mikrokopter. Flew both and i could hardly notice a difference. Although my friends quadcopter crashed with 3.1.2RC2 when we tried to autotune, it suddenly yaw and crashed. .Know idea what went wrong

        Video 13-2-14 4 25 50
        Shared with Dropbox
        • Developer

          Looking your video i think have gradually lost power to one motor, n fact begins to turn on itself slowly and gradually.
          Possible "LiPo cutoff protection" of the ESC not set correctly.

          • Hi marco,
            This was with a fully balanced charged 3S lipo. The ESC setting are the ones recommended in the ardupilot website. It was working very well on 3.1.2RC1. Maybe I'll get my friend to pass me the crash log and post them here.
  • I just flashed Arducopter 3.1.1, and I don't want my motor spin up when arming. However I couldn't find the MOT_SPIN_ARMED parameter in the full parameter list, where can I find it exactly?

  • Developer

    AC-3.1.2-rc2 has been released to the mission planner.  No changes for the APM2 but there are two very small changes for the Pixhawk (these will be released for the APM as part of AC3.2):

    1) GPS Glitch detection disabled when connected via USB
    2) RC_FEEL_RP param added for adjusting responsiveness to pilot roll/pitch input in Stabilize, Drift, AltHold modes

    All feedback welcome.

    • Developer

      Great news Randy, thanks!
      About "RC_FEEL_RP", i see the default value is "40", this value is in line with the old feeling input?

This reply was deleted.


Chris Anderson liked Zara Mae Pickering's profile
May 21
Azjeg liked Azjeg's profile
Apr 27
Benewake LiDAR liked Benewake LiDAR's profile
Apr 12
Gremsy liked Gremsy's profile
Mar 12