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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Bill, no, we don't log whether the input is from the RC or telemetry.  Maybe we will in a future version (good idea!).  It looks a lot like you were trying to disarm the vehicle in the air.  The throttle goes to zero, the yaw goes to full left (Roll and Pitch remain in the middle).   Not saying that's what you were trying to do of course, just that from looking at the RC inputs, that's how it appears.

Strange indeed. That last time I flew I didn't have any problems and I wasn't using telemetry. I'll refrain from using telemetry until I get back to the states. I'll also upgrade my firmware to 3.1.5 when I get back. Thanks Randy.



I've deleted your comment.  Nothing wrong with your message, but let's keep this discussion on topic.

no problem....

I just want to throw this out there largely because i dont understand why this fixed my problem. I was having trouble with Circle Flight Mode in FW 3.1.5 where having it set to what i thought was 4 meter circle produced erratic behavior. thinking that might be the problem, i increased the circle to 8 meters using Mission planner 1.3.5. In Mission Planner i believe this is the version that the change in measurement hasnt occurred yet (from CM to M) so if some one might comment with a theory, i am all ears.

i didnt think a 12 ft (4 m) circle would be hard to navigate but it seems it is on all my quads running APM 2.6 FW 3.1.5. as a side note, 8m performed flawlessly but i cant say it flew a 24 ft circle but it was close, winds were about 2-3 knots max. i tested on two of my quads, X650 and F450

Interestingly, I got the very same problem on my new Hexa with PixHawk.

As per logs, vibrations jump on both IMUs. And it looks, like full throttle is given prior to increased vibrations. So it might be, that vibrations are a consequence of full throttle, and not vice versa. However it is hard to say for sure.


In AC3.2 we have an EKF that can be used by setting the AHRS_EKF_USE parameter to 1 (then reboot the board).  It's not fully tested and I've heard it's a little jerky in Loiter (a problem we will resolve for AC3.2.1) but in any case this is the longer-term solution to resolving the solving this problem which is caused by accelerometer aliasing due to high vibration.

So, I just tried my first Auto Mission with 2 waypoints, which ended in a crash.  It looks like I had a GPS error of somesort when going from WP1 to WP2.  Anyone confirm?  I am running APM 2.5 (no external compass) with 3.1.5.  I have attached a copy of the log.



I've upgraded to 3.1.5 and was wondering whether to run compassmot or not, because of issues in previous versions.

3.1.5 is really stable, so compassmot is working well.

Though some copters hardware fail :-)

Thanks for posting Christian. That looked pretty scary. What was the issue?

Bill, what was that? I didn't get it honestly. 

Was it an commanded move or you did it intentionally?


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