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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    • I think you have to do esc calibration. Your motors do not seem to work together at the same time.

      • thank you for this answer, I remade a calibration from arducopter the problem was still present. maybe the esc by esc again??

        • Oh i upgraded the firmware from v3.0.1 to v3.1.2?  You have to do the complete calibration again such as compass, accel, and radio.  The reason for the 2 motors overheating is that your gyro/acce/ are not calibrated.  If you upgrade from v3.1.1, to v3.1.2, then no need to do these.And don't forget to calibrate the esc's again. i hope this helps. 

  • If I switch to loiter, flying only 5m/s with my 600 size Heli it starts to jerk and wobble around. It slams the brakes too hard to stop on the spot. I played around with the WP Accel and loiter-speed parameter but with no success.
    I think it’s very important to have a parameter to adjust loiter acceleration.
  • Developer


        thanks very much.   A guy called Jonathan Challinger is going to have a look at this.

  • hi i am was a newbie in rc and i just built my quadcopter with apm.. i still using default pid and i use H quad.. when i try loiter and position.. i got drift in that mode.. i test it in a bit windy condition.. please help me to read my logs and help me to resolve this problem.. i saw in youtube so many people got their loiter like a rock solid. thx. Im using 3.1.2 firmware.. my compassmot wa 4%.. and my x,y vibration was less than 2

    • Did you try Autotune feature?

  • Its a bit out of topic,,but here is link where u can check magnetic interference in atmosphere which affect your radio ,compass and gps...very useful..19 and 20.02.2014 was very bad..

  • Randy,

    here are the log files from the Quad.  There is a 9 meg one but the limit to the discussion is 7 meg.  Both recent long flights show the home alt reset.

    Let me know if this is not what you need.




  • Developer


         Instead of a telemetry log, a dataflash log is always recorded with each flight so you should have them on the board.  They actually give much higher data rates than the tlogs.

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