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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    • ublox does work normal when connected to ublox softwere...

  • The only thing I can see is that there may be a slight difference between 5V that the 3DR PM develops and the 5V the Attopilot produces.

    I think you can remove the 5V line from the Attop... It supplies it's own power.

    The two grounds are important. Be sure you run a ground from the BEC(s) of the ESCs to the main output servo ground rail.

  • Hi!

    I just ordered a Pixhawk to put on my s800 hexacopter. As I need 12v for video TX and gimbal controller card i have a 3s lipo onboard, the ESC/motors run on 6s. I just want to make shure my thinking is right.

    I want to power the pixhawk from the std. APM Power module from the 3s and monoitor the U and I on the 6s Battery (because it is the one that will become empty first...)

    Is my drawing correct???

    If it is correct you are free to use it on the wiki...

    Best regards Ronny Grimm3701675646?profile=original

  • I have been flying on drift mode and i like its performance. It is like flying a delta wing plane.  However, when i fly fast and let go of the stick, it does automatic braking by pitching up suddenly. This pitching up behavior seems to make the copter flip backwards.  Is there a way to reduce pitching up but allow the copter to slowly stop and loiter?

  • Hi guys!

    Where can I find info regarding the simulator with the 3.1.x version?


  • Developer

    It'd be best if people raised their support issues in the APM Forum.  There's a developer there called Jonathan Challinger who should be able to help with log analysis and other questions.  I'm right in the middle of a pile of dev for AC3.2 so I'm hoping that Jonathan can handle the bulk of the support calls.

  • Randy,

    There is a big fault in Mission Planner 1.2.97. If you accidentally click on the Wizard in Initial Setup while connected to APM, your frame type will be set to 0, although you left the Popup screen!!!

    If you fly with this setting your copter will crash within seconds in stabilize due to big shakings. It costs me only two props, and 2 hours frustation :-)

    So please speak with Michael O.

    • Yep, I just got caught out by this today. First time flying in several weeks (British weather!). Upgraded to 3.1.2 and latest Mission Planner. Did a quick scan of basic PIDs etc to check they still looked ok. Took off in stabilise. Instant flip and crash.

      Turned out that the frame type had been reset to Plus. Luckily no damage done as I was being pretty careful on the first takeoff with a new firmware, but this shouldn't have happened.

      The so-called "wizard" had opened but I hadn't done anything in it; just closed it right away. The software shouldn't write anything to the APM without my telling it to.

    • Same problem, updating APM 2.5 with 3.1.2, crazy HUD during the pre flight vérifications
      luckily for me I did not take off
      good evening to all

    • yes, had the same issue ! 

      but was able to recover the Props :-)

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