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 –


                  • Jay,

                    Johnatan said that he's revamping the navigation code for 3.2 - I don't think he'll be chasing bugs until that's done (as far as I understand).

                    All the best,


                  • here's the log.

                    2014-04-12 03-05_137.log

                • Thanks Randy,

                  I appreciate that you don't let it "slip". I'll be keeping an eye on it after 3.2 is released too. In the mean time I'll disable the climbing phase. Tonight I thought I saw a twitch in the descending phase. Since it's first time that I noticed, I don't think twice about it - if it happens again I'll report - the two may be related.



          • Mihai, this is AC3.1.3-rc1.

            • I know Jay. There were two bugs:

                - first causes instability (the twitch) on RTL in the climbing phase

                - the second one causes the motors to lock down on large throttle/roll inputs

              Patch 3.1.3 rc1 fixes the second bug, but not the first. That's why you still see the twitch, but not the crash.

              I can understand that after spending their weekend in office tracking down a bug by "some guy" they're not willing to go in it again, but it will keep resurfacing (like it did now with you) until they fix it.



      • thanks Randy.

  • I was looking around the wiki and forums to see if there is a function in Geofence where it has the ability to just stop the copter from actually breaching the Geofence and without it triggering RTL or Land auto-flight mode. As in it cant get past that point and then it just stops there until you turn it around to bring it back rather than it switches into RTL or land. Is that possible?

    Or alternatively have it so it has a time frame that it stops there for say 1 min and if you haven't changed its flight path to come back from the Geofence, only then it will switch to RTL or Land?

    • Thats a good idea.  I fly with a guy who uses naza and it does that.  We boosted his transmitter signal and wanted to see what the improvement would be.  He hit the fence in naza and it does just that.  Stops and will not let you go past it, but you still have full control of the quad.  Its like the super simple fence around you in reverse.

      • Yes I saw that on the NAZA as well and hoped the APM would do this with the newer fw's. I think its more useful like this so you don't risk overfly the boundaries. Alex Il'l do a bit of reading around the forum and see what's wrong with it before deciding to use it. Thanks. .

        • They must have added the Fence function to Naza lately. There wasn't such thing when I was using it 2 years ago.

          APMs wide selection of functionality forcing DJI to add new functions to Naza. I am sure DJI is not very enthusiastic about adding stuff for free (generally not their style) but they have no choice if they want to stay in the competition.  

          Do you happen to know what firmware your friend's Naza running?


This reply was deleted.