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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      • Hi Shyam, thank you so much for the reply. During the mission planning, i did put loiter_circle 10.  Also in the full parameter of my copter, i have these values: loiter_radius 20, loiter_rate 30...Now i don't know where i made the mistake?

        In fact i also tried this:  I hovered on Stabilized Mode at about 20 meters high, then, i changed the flight mode to Circle. The copter simply remained on loiter. Maybe you can give me instruction on how to do Circle Mode?  Again thanks.

  • Hi Guys,

    Just a quick question, I need your help with.

    I just upgraded from the old version 3.0 RC8 to the latest firmware, Do I need to recalibrate, or dose everything stay as it was?

    Kind regards


  • hi,

    Can someone tell me why I have an imbalance between 1-2 and 3-4 engines?

    the bird is properly balanced, and the gyro are ok. I tried to reverse the + ESC engines between 1 and 4, 3 and 2. but I still have this imbalance.

    I will seal the last three logs with a battery of different weight

    Thank you in advance for your help


    • Did you do esc calibration? Motors will not spin at the same time if you don't calibrate esc's.

      • Not all ESCs can be calibrated.

        Did he state what ESCs he is using?

        • ESC 30A rctimer with cristal :)

          I'm testing autotune this day and no problem. But I've always an imbalance between 1-2 and 3-4 engines

          And I've made a calibration ESC with APM, and 1 by 1, it's same problem

          • Hello

            Look to the windings of the motors.
            There are probably different.

            • I thought about it, I reversed the engines 1 with 3 and 2 with 4. I always engines 3 and 4 are much more in demand.
              I do not understand what causes this imbalance.

              • Look at the copter config, X or H! The motor rotation is diferent. Just my two cents...


                • I'm in config V with my TBS frame ...

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