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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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.

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.



     Apparently it's suppose to be connected to the SBUS pin which is just to the right of the "RC IN" pin but I hear it doesn't work yet (it's on my list to look at).

I have been using the RC in port with my Pixhawks with Futaba SBUS. All working good so far

Try to lower your D rate both Pitch and roll by 5, start it with pitch.


    Yes, SBUS seems good if you're on AC3.1.1-rc1 but the RSSI input is not working yet i think.

Hi Jeff P.

There are some people having problem to connect SBUS, me too. FrSky receiver is working well with Pixhawk. I think there is some variation on receiver model.

What model of Futaba SBUS are you using ?

Odd, my interference goes away when i move the TX, never thought to move the camera which is in the Front of the Aircraft and the GPS is in the rear. i know when i relocate the TX, it reduces interference. i will buy an immersionRC and a good camera an hope it solves my problems. thanks for answering, it is appreciated and helpful.

hello ..yesterday i was upload the code to my ATG600X4 with NTM2830 750kv and 4s 5000mah battery ..everything was ok in STABILIZE MODE but when i was going to ALTITUDE MODE ..i had a crash ..please see what happend at my quad..





I use Futaba R6202SBW
Works perfect

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