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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    • Thanks a lot! Clearly, Pixhawk will take the roles!
    • Marco, thank you for your replying. I have another question about the fw 3.2. Will it support APM 2.6? Thanks
      • @weidan i think fw3.2 and so on will always support apm 26. Because apm 2.5 and 2.6 was basically same only with and without internal compass.. another story if compare with pixhawk..

        *correct me if im wrong.
        • Developer

          Of course, 3.2 support APM 2.x but without the EKF and, i'm sorry, optical flow if Hybrid is enabled, something we had to disable because there is no more space in the APM for all this things.

    • Developer

      Hybrid mode is inside APM Copter V3.2, which will be released in a few week.
      Probably take another name, as well as "Loiter" could become "Position Hold" (more appropriate to other systems).
      In my opinion become the most used flight mode in APM Copter, because it corresponds exactly to "GPS" of DJI and "PH" of Mikrokopter.
      It's a "flyable Loiter", not so tied to navigation when you reposition the quad.
      At the moment please do not fly the master, there's some little issue to be resolved.
      Tthere's a lot of great improvements in the future release (EKF, Hybrid and other), many interesting for owners of Pixhawk and VR Brain.


      • Marco, i have been flying and using AC3.1.1-rc1 for the last 2 months for video on weddings and surveys of vegetation/plantation. There's a slight twitching when flying in "hybrid loiter" but i still say, it is acceptable and will not cause the copter to crash/flip. I am using APM 2.5.2. Anticipating for the early release of AC3.2. Thanks Marco.

        • Developer

          I think this "twitching" is normal because in the Hybrid code there's a sorta of "virtual switching" from alt-hold controller to position hold and viceversa.
          But now there's some evolution inside the code about Hybrid, stay tuned for the official exit.

      • AC3.2 is the most exciting firmware release so far. Those are handful improvements over AC3.1.3, therefore my expectations are heavenly. I wish a not as much bug on this ;D.

        Now on its 62% completion... I don't think it will be available in a week or two. Let's hope for the best.

    • At the risk of sounding stupid, what is hybrid mode??

      • HM is like a faster loiter. When your sticks are centered, its the equivalent of loiter , but when you start moving about the sticks, it changes to alt-hold with the direction your sticks are taking the copter. Search YT for Marco Robustini and within his many videos he has a demo showing it in action.

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