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.

You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –


      • Moderator

        No, this is with v3.1.3, using the same parameters as the APM2.5. My vibrations are low, all I changed was the APM and now I can't get Alt_Hold to alt hold so it must be a hardware difference.

        • Graham, I had 3.1.2 working fine with Alt Hold on my APM1 board. Ive now loaded 3.1.3 but haven't tried it with Alt_Hold yet. I also have a sonar fitted to it

          • Moderator

            Thanks John, please let me know if you test it (without sonar), I'd be very interested to know if it's my board or APM1's in general.

  • What causes different offsets? I am doing the offset calculation but keep getting different results, I have got my compassmot down to 2% so I am wondering if I should try the learn mode during flight? Any advice

    • Offsets come from magnets, compassmot comes from current draw through nearby wires. Soon we will also have soft-iron adjustment, which will correct for magnetic field distortions from nearby chunks of non-magnetic iron.

  • I'm still running 3.1.1 on my Hex, just loaded 1.2.99, went to the full parameter file and loaded the latest saved parameter file from this morning where I change the PID's, everything is working fine, stabilised, land, RTL, loiter and Tx failsafe.

    I have not gone past 3.1.1 because I don't want the ability to take off in alt hold or loiter as I have no use for it. I have said it before my Hex does everything it is supposed to and it flies like it is on rails. I have just changed my dual rates to 30% from 15% and it now has given me a lot finer control for precise close in flying to objects.

    I have said it before and I'll say it again, Randy and the Dev team have done a fantastic job with APM, for those of you that can't fly without the aid of loiter or alt hold I hope your flying in an area where there are no cars, buildings or the general public, may the force be with you.

  • Hi, if I update 3.1.2 to 3.1.3 via mission planner. Do I have to recalibrate all sensors?

    • Developer


          No, all parameters are carried over.  The update from 3.1.2 to 3.1.3 is a very small change.

      • Thanks, just update 3.1.2 to 3.1.3 all OK. but I can't find "Position Mode" in Initial setup--> flight modes.

        I use MP version 1.2.99 build 1.1.5197.12871

  • @ Randy  You can view it here also as I did a quick upload to look at it. If you need it on the support forum I of course can do that my friend. As you will see it is turned off and the flight went as planned so I am sure its something in the values for the glitch protection. 


This reply was deleted.


Gremsy liked Gremsy's profile
Mar 12
DIY Robocars via Twitter
RT @chr1sa: Donkeycar 4.4 released with tons of new features, including path learning (useful with GPS outdoors), better Web and Lidar supp…
Nov 27, 2022
DIY Robocars via Twitter
RT @NXP: We are already biting our nails in anticipation of the #NXPCupEMEA challenge! 😉 Did you know there are great cash prizes to be won…
Nov 24, 2022
DIY Robocars via Twitter
RT @gclue_akira: レースまであと3日。今回のコースは激ムズかも。あと一歩 #jetracer
Nov 24, 2022
DIY Robocars via Twitter
UC Berkeley's DIY robocar program
Nov 24, 2022
DIY Robocars via Twitter
RT @chr1sa: The next @DIYRobocars autonomous car race at @circuitlaunch will be on Sat, Dec 10. Thrills, spills and a Brazilian BBQ. Fun…
Nov 24, 2022
DIY Robocars via Twitter
RT @arthiak_tc: Donkey car platform ... Still training uses behavioral cloning #TCXpo #diyrobocar @OttawaAVGroup
Nov 20, 2022
DIY Robocars via Twitter
RT @emurmur77: Points for style. @donkeycar racing in @diyrobocars at @UCSDJacobs thanks @chr1sa for taking the video.…
Nov 20, 2022
DIY Robocars via Twitter
RT @SmallpixelCar: Going to @diyrobocars race at @UCSDJacobs
Nov 8, 2022
DIY Robocars via Twitter
RT @SmallpixelCar: Race @diyrobocars at @UCSDJacobs thanks @chr1sa for taking the video.
Nov 8, 2022
DIY Robocars via Twitter
RT @PiWarsRobotics: Presenting: the Hacky Racers Robotic Racing Series in collaboration with #PiWars. Find out more and register your inter…
Oct 23, 2022
DIY Robocars via Twitter
RT @Hacky_Racers: There will be three classes at this event: A4, A2, and Hacky Racer! A4 and A2 are based around UK paper sizing and existi…
Oct 23, 2022
DIY Robocars via Twitter
Oct 23, 2022
DIY Robocars via Twitter
Oct 19, 2022
DIY Robocars via Twitter
Oct 18, 2022
DIY Robocars via Twitter
RT @NeaveEng: Calling all UK based folks interested in @diyrobocars, @f1tenth, @donkey_car, and similar robot racing competitions! @hacky_r…
Oct 13, 2022