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 

    Is it possible to connect a sonar to Pixhawk not for ALT Hold ... but to use it for a real time distance measurement displayed in MP Flight Data screen ?  Also I asked before but got no reply about using wind speed cups mounted on the top of a multirotor to provide the wind speed of the weather not the speed of the copter ..also displayed in MP..

    Cheers for any ideas 


    • Kind of pointless given sonars have a range of < 10 m. Unless what you want is so too see this value but have the APM ignore it. Have you tried setting the sonar gain to 0 so the sonar value is never actually used. This mgight make the value available in mp after you enable sonar.

      • Hi I want to use it for obstacle avoidance while flying close to my target , So while hovering near my target i want to know how fay away I am .. I would like to not go too close so I want a range from 1 to 5 meters so I can look at my screen and see a distance figure displayed .. either in my FPV googles or MP screen on tablet ..

  • @Jonathan, this is the problem i have discussed with Randy and he advised that you are the best guy to spot it. when the first command in mission planner is 'Takeoff' the next command following 'Takeoff' is not executed. i tried this on two different  APM2.6 and One Pixhawk. all other navigation commands seem to be working fine. attached is the log file when flown with AC 3.1.2. i am facing the same problem with AC3.1.3. Randy mentioned this happens when wpnav-rad is set to 0. i did set the wpnav-rad to 0 in all my missions.


    • I'll add it to my todo list - in the mean time, it sounds like setting your WPNAV_RADIUS to something within the documented range would be prudent?

  • @randy, i did send a log to jonathan challenger about a month back on your advice but did not get reply. but i did keep wpnav-radius as zero. i will try the takeoff command by changing the wpnav-rad to a higher value than zero. may be 2m.

  • how Up to Date is the Vibration Guide line in the Arducopter Wiki?  

    By That i Mean, has the sensitivity settings changed between Firmware 2.9 and the Current Firmware 3.1.1 ? please advise

    • Your stick is below center at almost all times in your log.

      • yes the THR_MID is 400 so it would be below center

This reply was deleted.


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