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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  • Randy said:

    undocumented SPRAYER feature in ArduCopter

    is there any official info on this feature? thx.

  • Hi - I've just started to work with Pixhawk snd XBEE Wi-Fi (Switchscience  S6B).

    I have followed the directions given in the 3DRobotics  tutorial ( ) on how to connect

    the two together.  The problem is that Mission planner is not able to recognize


    a)  XBEE was set up using XCTU.  

    b)Two XBEEs are able to communicate with each other

    through a common access point.

    c) "ping" was successfully used to detect both XBEEs through the common access point.  

    d) One XBEE was connected to an Arduino Mini Pro board using the hardwire serial 

    interface (Vcc, Gnd, Tx, Rx),  A second XBEE was connected to a PC using a USB connection.  I was able to receive data from Arduino on my PC using the this wi-fi set-up.

    I think I have completed the setups for the XBEEs properly.  What could be causing

    the failure to recognize PIXHAWK by Mission Planner  ?

    Any comments/suggestions would be appreciated.


    • Developer


      Maybe the baud-rate is wrong somewhere?

      The Xbee's will be talking at some baudrate and the Mission Planner and Pixhawk must use that same baud rate.

      Selecting the baud-rate on the MP is easy, it's a drop-down next to the connect button.

      On the Pixhawk there's a SERIAL1_BAUD parameters that can be used to change the baud rate of Telemetry1 port.  By default it's "57" which means the Xbee must be running at 57600.  If the XBee is running at a slower rate then both this parameter should be changed to match.

      • Randy,Thanks for your quick reply.

        I have confirmed the baud rate of the XBee and Pixhawk, but is a situation that can not be still connected.

        Do you have any cause to be considered in the other?

  • Question about position hold on V3.2rc12;

    in several quads, when flying fast in POSHOLD and release the sticks, the quad slows down, tilts against the flight direction and stops. (basically this sould be th end of the stop) but it then tilts back in flight direction slightly, flys forward a bit more and comes to a complete stop.

    which parameter would you tune in this case? 

    as mentioned it happens in 4-5 different local quads with different setups.

  • I went back to V3.1. My quads don't seem as stable with V3.1.5.  Could something have changed that would affect vibration between V3.1 and V3.1.5? It seems that with V3.1.5 my x and y values diverge from each other more than they do with V3.1. If it's calm tomorrow I'll do similar flights with both versions and post the logs.

    • Why don't you try the 3.2? it's beta but many test were done, my cuad flies better with it ;)

      • I'v been thinking about giving 3.2 a try. It's encouraging to hear that your quad flies better with it. What size quad are you flying? I have a Talon 550 and Tarot 650.

        • A cheap chinese 550 and a Tarot 650 with extended motor arms, the Tarot is new, at first I try 3.15 to avoid Beta but I convinced with the other cuad to migrate to 3.2, just now I'm going to try autotune with it . This is my Tarot I'm going to comment my results with Tarot

          • Nice job on the Tarot. Looks like it's pretty stable on 3.2.

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