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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  • Hello,

    can somebody please look into this? When i turn the Copter and fly forward the copter will yaw and rolls to one side. You can see this in this video at 3:30 ( there is no yaw or roll input and on the OSD the copter thinks its roll-axis is in level. This part is in the picture in the attachments. This is also a big issue when flying in Drift-mode. If you have no stick input for several seconds the copter will be in level again.

    I also found a bug in ROI, i am using a servo gimbal and can controll the pich via CH6. As soon as a ROI-command comes i can not control the pitch anymore, even in different flight modes, i have to disconnect the battery to regain control.


    2014-02-02 15-43.log

  • Moderator

    Some advice please:

    1) My Alt_hold is good but I feel it could be a little better. There's quite a bit of height lost in forward flight which is regained again when stopping. (APM2.5 is cased and baro covered and shaded).

    Current settings are:

    Alt hold P - 1.0, Thr accel - P - 0.75, I - 1.50, D - 0.010, IMAX - 6.500 (no longer sure of what the defaults were).

    2) Loiter is very good but fidgety, even in low wind, it always twitching slightly. Other videos I've seen of 'copters in Loiter show a much smoother ride than mine.

    My Loiter settings are: Loiter PID - 1.0, Rate Loiter P - 1.0, I - 0.500, D - 0.012, IMAX - 3.0, Loiter speed - 800.

    What can I change to improve things?

  • AC3.1, APM2.6, setting WP

    1) WP1

    2) DO_SET_ROI

    3)WP 3,4.....10

    From WP1 to WP3, Quad point  WP2(ROI), after that, QUAD point next WP

    how to set ROI for entire WP?

  • Any word on the barometer issue (asymptotic altitude loss) caused by shaking the board? Curious to hear if my inertial acceleration coefficient solution fixed it. It seemed to be due to the MEMS sensor design related to mechanical forcing.

  • Developer

    AC 3.1.2-rc1 (release candidate) is now available in the Mission Planner's Beta Firmwares link.

    There are no changes for the APM2 (beyond the firmware name) but it fixes a potentially serious bug for Pixhawk.

    We found that if the Pixhawk board temperature climbed above 65 degrees C then some boards would see the altitude readings jump by 200m.  If you were in altHold, Loiter or Auto this could cause the copter to descend very rapidly.  The fix increases the input-output pin speed settings so they can keep up with the high cpu <-> baro communication rate.

    Many thanks to Darrell Burkey for supplying the log file that found this bug.

  • Hi

    Other than sbus any chance of JR Xbus support being added. The link posted below shows that Xbus mode b is quite similar to sbus.

    Having Xbus work on pixhawk will be a great help with wire management for those of us using new JR transmitters like XG14 as the ppm encoder solution is very messy on small frames with all those wires.



  • Well is Futaba Sbus support only for Pixhawk at the moment?

    Is there a Sbus support for APM 2.5 (FW 3.1)?

    I already have a Futaba sbus Rx (R6303sb) that I would like to try. I must utilize sbus since this Rx has only 3 channels.

    If not, I will have to get a compatible Frsky Rx.

    Would someone please let me know.


  • Got some flying in over the long weekend. This thing is locked in so nice with 3.1


  • once again gathered scheme Octo Quadro copter and once again noticed a bug when calibrating regulators "All at once calibration" is calibrated 7 regulators and 8th not noticed that the firmware 3.0.1 checking on 3.1 and yesterday happened 3.1.1 after unsuccessful attempts to connect with a PC without changing anything save for example in the Setting up Flight Modes unplug try again and calibration passes
    ps other oddities me not seen for a year of successful flights, my previous message (above) on the collapse was false (planting-UPS with snow) effloresced soldering wiring regulators and one of the wires fell

    yet tested the same scheme Octo Quadro copter with different screws to the top of the stand 1045 and 1000 kV lower 1260 and 530 kv 3 battery pack, fly perfectly but have to deal now with vibration according to a log reaches 4-5 but I will correct, after a test flight at -20 C satisfied

  • Hi Randy, Marco and the DEV Team,

    I have just loaded 3.1.1 and the Hex is still flying like a dream, the stability is amazing and it gives me an enormous amount of confidence to just want to go out and fly, fly, and fly some more.

    Thanks a heap for all your dedication and hard work, like was you to Michael with MP.

    Great work


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