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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            • Rate Loiter P

              • Ya i already increase the rate loiter p and the problem still occur and the movement of the quad more than i put the rate loiter p in default. I already increase with small amount until 3.0 . You can look in this link with the new video and is it normal the GPS moving a bit? In this video i havent increase the rate liter p.


                Thx @willy for keeping in touch
                • Here my pid setting and logs after i set the loiter pid and rate loiter d

                  2014-03-28 17-57-01.log

                  Capture loiter p 1.jpeg

                  • @willy, after change loiter PID P to 0.2 and Rate loiter D to 2.8 its better setting and not a lot big movement but not really lock in position still drift. and the compass already did great I'm trying to do waypoint mission and super simple mode.. both doing great and I'm comparing to my phone compass its doing same only miss 1-3 degree.

                    this the newest video after i change the setting


                    @randy, hi randy thx for replying. ya. the HDOP quite low that why I'm confuse why I'm not lock at position in my loiter. I'm using Ublox neo-6m but not cn06.

                  • Developer

                    Generally people don't need to adjust the Loiter PIDs.  The defaults should be fine.  The HDOP values are suspiciously low at only 0.7 ~ 0.9.  Are you using a fantastic Ublox or the not-very-reliable Mediatek?

                  • Andre, please lower your Loiter PID from 1.5 to 0.2. Also redo Compass and Accel Calibration.  Verify that your copter faces North if you point it to North and it also faces SouthWest if you move it towards SouthWest. Some APM 2.6 with external compass have problem with compass orientation.

  • With PPM receiver, Channel 6 pass through not working in Arducopter 3.1.2 however its working in Arduplane 2.78b

    I am using 4 channel Receiver from Frsky. In PPM mode, This receiver outputs upto 8 channels on the PPM stream and also have PWM type RSSI.

    On the quad side, I have assigned APM 2.6 output ch 6 to the zoom control for my 10x zoom cam.

    APM 2.6, output Ch 7 is assigned to the recording On/Off operation.

    It seems that there is bug in the Arducopter 3.1.2, which needs to be taken care.

    • I've been looking to control zoon with the TX.

      What camera are you using?


  • Did loiter have any change on this release? I am asking this because before loiter was flyable, now it feels loose and the input's are not responded adequated until I grow stabilizer roll and pitch P which make stabilized very agressive. Another question is, what can make the copter fly leaning a little bit to the sides when going forward while in loiter? In stabilized it flies nice.

  • Hi guys,

    I created a small quad (F450 frame based) for a friend with an apm 2.5 (FW 3.1)
    As he is just starting out I wanted to make the apm a little less aggressive on the lean angle.
    By default this is 45°, so I want to reduce this to about 30° (nice and mellow)

    I changed the ANGLE_MAX from 4500 to 3000.
    When I did a test (stabilize) it still was tilting very aggressively, went out of control and had a minor crash.
    During this test I gave max pitch on the sticks to see if the predefined angle angle was working.
    Well it didn't unfortunately.

    Do I need to alter the ANGLE_RATE_MAX as well? Currently this is still on the default of 18000 (180°/sec).
    Other suggestions are welcome :-)


This reply was deleted.