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 guys, AltHold motors pulsing problem in my hexa :(

    My baro is covered with foam and my vibrations are under control (I guess...), but with default pid's when I engage the Alt Hold the copter starts to make small pulses on motors and sometimes starts to oscillate the altitude (almost scare...) . I tried to low the Alt_Hold value to 0.5 but the oscillations becomes worst.  Tried to disable all dataflash logging, but no luck.

    I have just a Tlog that I would appreciate if you can analyze and give me some help.

    APM 2.6, Frame F550 clone, Sunnysky 980kv motors, 30A simonk esc's.

    Thanks in advance!

    P.s.: The first part of the flgiht log was with 1.2 Alt_Hold value, and the final seconds was with 1.0 value.

    2014-01-19 23-06-34.tlog

  • Hello ,

    I have small issue with average throttle , i have APM 2.5 with latest code and i have RC Hitec Aurora 9 my throttle lowest value around 1100 and max is 1900 , however the mid value of the throttle is set to 600 and up to 900 or so. now my question is to increase this value? when ever i arm the copter and when the throttle reach 50% the motors work 100% speed. 

    i cant hover i tried Alt hold, Stable mode all same!.

    please help.

  • Sorry if off topic.  I am picking up an Tarot Ironman 1000.  I currrently have a 960 and 650 Tarot and PID tuning was fine.  I just got the PID's close and then ran an Autotune.  Does anyone have some general PID's for the Ironman, It is my first Octo and not sure if I can Autotune on the 3.1 defaults.  My 960 and S800 have higher then default PID's and higher Stab P.  I have read info that suggests that on the Octo I should lower the PIDs to start.  Any help would be appreciated!

    Many thanks  JEFF

  • I have a pixhawk coming in and was wandering were do we have a 5v input for RSSI measurements on the pixhawk and how to connect it?

    Is it supported with the 3.1 rc1 firmware?

  • Is the sonar used for any altitude hold functions in 3.1? I used the sonar in the earlier versions pre 2.9 but my understanding was that it was no longer used for altitude hold below 15 feet and was now used solely for terrain following/collision avoidance.

  • Hi,

    Did anybody test AC 3.1 on an APM 1.0 board ? (a b 2560). With AC 3.1, my sonar doesn't show any value in the test section, while still working well with previous firmware versions... Am I the only one in that case ?


  • Hi,

    Recently i changed from 10x4.5 plastic propellers to 10x3.8 Carbon fibre propellers. After the change my quad always seem to oscillation in stabilise mode even after redoing the Autotune. I am also using the provided Vibration dampers with pixhawk. I have run compassmot and got 8% interference only. I have checked the alignment of motors as well as the propeller adapters. Everything is the same as before when using the plastic propellers which were quite stable. My quad specs are as follows,

    4 Turnigy SK3 Aerodrive 1130kv motors

    Talon V2 carbon fibre quadcopter frame

    Gemfan 10x3.8 Carbon fibre propellers

    Pixhawk+ 3DR External compass & GPS+3DR Telemetry+Power Module

    I have attached a log. Please help me to diagnose what the issue is.

    2014-01-18 18-54.log

    Photo 18-1-14 9 46 02 pm.jpg

    Photo 18-1-14 9 46 21 pm.jpg

  • Hello,

    I have already asked in the forum, but there is no answer.

    Is there already support for pitch and roll for the camera on the PIXHAWK?

    Since the external I ² C LED is not to buy, also lack the ports for GPS and Arming status. So we could use our old Led hardware.

    regards Peter

  • Today, I just got PIXHawk from fedex. I do install Board to my Quad and used Beta Firmware 3.1.1-rc1.

    It's very smooth control and Perfect's Loiter. But, I saw bug about Battery warning is no have alarm from buzzer. But, Battery Failsafe is still work.

    I don't know RSSI port. What's connect RSSI Port? Randy, You can answer me please.....




  • Hi Randy

    I watched a video of yours where you explored the instance of GPS interference from a Sonar device. I am currently experiencing the same interference from an FPV setup, Devention 5803TX 5.8ghz and a DV04 Camera with a clover leaf antenna. if you dont mind, did you solve this problem?

    My TX5803 is about 15 inches and Below the UBLOX GPS on my APM 2.6 i got from 3DR robotics.

    i guess some copper shielding tape would work but what would need to be shielded, the bottom of the GPS? the TX5803? Does GPS work in the same GHZ range? 

    thanks in advance

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