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.

Views: 151248

Reply to This

Replies to This Discussion

Yes I would try that, make them 3.0 for roll and pitch... you can leave yaw as it is. The rate gains that Randy was pointing out seem too low to be causing your problem.

I think the rate gains could even be a bit larger, but for your next text maybe leave it as it is. However I would also lower the integration gains (I for rate roll and rate pitch) from 0.085/0.08 to 0.010. Normally your quad should also fly pretty okay with I's and D's to zero if your P's are not too high...

Does the quad respond good (good directions) to minor pitch/roll/yaw inputs? If it does, try setting the parameters as I just said ;-). Start with minor deviations, go to bigger deviations and in the end try fast deviations. (but I would avoid moving your stick instantaneously to their extreme positions...)

Let me know how it flew ;-)


Thank you for the feedback.
I will certainly give it a try as suggested.
Hopefully the weather stays fine for some testing :-)


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.

Hi. i got problem with my loiter. i want ask help from anybody how to fix this thing.. i using  H-quad. with apm 2.6. i got everything works but the loiter not rock solid as it should. the loiter still moving but kindly lock in one position but in big area. like repositioning but the wind very light in my situation. almost no wind. flying in stabilize and alt hold was great.

my vibration less than 1 and -1. and i got 7% on compassmot. and i got 10-12 satelite. i also did autotune before i test loiter. im using moon gel as my vibration dampening. anyone know how to fix it?

please kindly open this link to see the video of my problem.

and here i attach my log. thx before for helping.



There's nothing wrong with your copter as shown in your log except that in Loiter Mode the values of your roll and pitch are too low(in the ATT graph). You might want to increase your Loiter PIDs to keep your copter in one place.

Hi there,

is there somewhere a description of the datalog fields (other than I'm looking in particular for ThrOut and DCRate in CTUN which change curiously just before a random crash from LOITER mode (firmware 3.1 on a hex).




This is my pid setting.. sorry for newbie question.. which one i should increaise.. rate loiter? and can u estimate how much should i increase the pid?

thx for replying @willy


     I think that's the best page.  Often during a crash, you'll see the throttle climb up to full as the copter starts leaning over.  This is normal and it's caused by "angle boost".  This is there to try and correct for the loss of vertical thrust caused by having the copter leaning over.  You might be able to confirm this by also graphing the ATT message's Roll and pitch angles.

What happened to getting support over in the APM forums? I was trying to do the right thing and move my questions over there, per the mods here...why is it always the nice guys that get the short end of the stick? :)

I've been posting stuff over there and it seems like nobody is really there. Should I just thow in the towel and join the party here?

I'll take that as a, here goes!

 (all of this AC 3.1.1 on a Pixhawk)

Loiter Climb and Descend Rate

I've searched the wiki and google but I'm not sure I am understanding this correctly, so if you know, please just help a brother out:
I want to ascend and descend faster in Loiter mode. What parameter do I change for this?
I've noticed that, while in loiter, my quad will never really hold a steady heading, and videos show a slight but noticable wagging left and right.  What is the proper way to diagnose and tune this out?
- Motor 4 not being logged
I was looking at logs recently and noticed that motors 1-3 show expected values, but motor 4 is just a flatline. Can somebody confirm that we can see four motors for a quadcopter, or suggestions?
-Battery Failsafe Error even though Batt Failsafe Disabled
I had a battery failsafe event/error even though it was disabled. Is this possible? I'd really like to get to the bottom of that -- More info here:

Brit, I answered you over there. ;)

I was going to say.... I had a questioin over there on "APM->Code" about Github that wasn't getting any bites, but I looked and maybe about half of the posts there had no responses.

BTW, I don't know if there's a better place to put github questions/problems...

Thank you, Rob, much appreciated.

Might you have any thoughts on the battery failsafe topic? This one has stumped me -- maybe a fresh pair of eyes would help?

Reply to Discussion


© 2019   Created by Chris Anderson.   Powered by

Badges  |  Report an Issue  |  Terms of Service