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

I thought I would just show you my little trick with a Lego block, I took a square Lego brick removed the center post .. made a small hole in it with a heated pin.. then added foam inside and hot glued the brick over the Baro ..making sure it was nicely sealed around the smd chips... What this does it add a baffle and stops pressure buffeting the sensor . similar to how DJi's IMU box is made ..result better altitude hold .. Enjoy..


hi everyone. Can someone please help figure out what's happen here. It triggers to RTL even without entering into rtl. I disable my failsafe (both battery and gps). Attached herewith my log.


Sorry guys, I don't want be boring or abusive but I had no response from my last post with dataflash log (post in page 39, maybe forgotten because that),
I'm desperate with this Alt Hold issue, I think that my vibrations are acceptable (you can confirm in the log with IMU data activated), I'm hoping a answer from you, if no responses/solutions  I'll stick a older firmware in the APM.

Thanks in advance


Jeff P

Oh, R202SBW is compatible to Pixhawk!

My R6303SB may be fault one. Get other Futaba unit.


Daniel, you are using the latest 3.1 I imagine...

Also it would be better to link your original post so it would easier for people to find it.

The link to your original post is right on the left of your name. Click on that little horizontal 8 symbol...

Hi Jay,

Search for errors in the log, ERR (an error message) or for flight mode changes and what happened just before it went to RTL


because no one has an idea where the error is.?
thanks for the answers


Thanks Peter.

On Yesterday, I and my friend had test Double Pixhawk with Arducopter 3.1.1-rc1. We have use parameter's Default are very stable but Them need little tune.



     Looking good!  Those are insanely stable.

Thank you, Randy

      Pixhawk is very good about respond for control.



     I just seeNew Beta Firmware Arducopter 3.1.1-rc2 in Mission Planner. What's have fix bug or new Feature?

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