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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  • Hello!

    I mounted a Spidex Micro Quad with APM 2.5 and FW3.1.2

    Anybody knows the "correct" PID for this tiny quad?

    Dimensions (center to center)

    right to left = 165mm

    front to back = 145mm

    1804 2400kv

    5x3 props


    • I would suggest an Autotune is the best way to get the good PIDs values. did you try it?

      • hello!

        To try autotune... first the quad should fly safely....LOL

  • Developer

    It's just a matter of developer time.  The requests for feature enhancements far outweigh the actual amount of time that the developers have to implement those features.

    • Thanks Randy for your replies .. I would like to ask that this request be put on the list of "to do's" It would be great and safe to have the feature where we can limit the altitude to a specific height .. Not triggering anything but not allowing the copter to exceed the height set. This is what the CAA  FAA  and CASA ... would like to see as part of our safety systems when we show them our operations manual .

  • I tend to agree, especially in the case of beginners who are more apt to crash then save their copters. at least with a fence, it gives both the quad and the beginner pilot a chance to work with the aircraft to bring it back home or fly it around and learn how to get out of a situation like a high altitude mistake.

  • Just out of Curiosity, is there a way to set a Ceiling on how high an Arducopter Drone can go? as a new flyer, i would like to limit it to about 30 feet  until i become more accustomed to piloting a quad. this way i would never have to worry about it getting too high to see?

    • Yes, you may use the geofence.

      • So, say the local control tower says you can fly but we will restrict you to 400 ft . this can be set .. in the fence altitude and set it to "do nothing"  or should be be specified "loiter" at that max altitude ??.. I have heard stories not to use the "fence"  as when the copter hits it . things have been going wrong and leading to fly aways and crashes .. is the fence function reliable??  We have now converted three of our machines to arducopter . which we have been happy with, besides the not so steady loiter and pendulum effect in light to medium winds ... we used to use MAX altitude .. all the time on DJI WK .. just set 120m and forget it ... copter goes to max altitude we take our photos move left and right or down abit  . and then land ..perfect so it would be nice to do the same with APM.. we were just scared to use the feature ..thanks Reuben

        • Developer

          Then max altitude fence will trigger an RTL if you're in Acro, Stabilize or Auto.  If you're in Loiter or AltHold it should stop the copter about 2m below the fence but if you somehow break through it (like a wind gust pushes the copter above the fence) then it will trigger an RTL.

          I think the altitude fence is generally pretty safe to use.  The issues we have had with the circular fence is that really bad GPS positions can lead to false positives and then the copter flies off to where it thinks home is which may actually be quite far from the actual home.  GPS Glitch detection has made it more reliable.  There's still one additional fix that we plan to put in which is to ensure that the autopilot doesn't try to re-take control more than once every 20seconds.  So at the moment it will retake control after 20meters.  This means if the GPS position is really bad then the autopilot may retake control too often and not give the pilot much opportunity to take back manual control.  For these reasons I'm not really promoting the use of the circular fence much.  It will generally work but I've actually heard more complaints that it's caused their copter to fly off than I have positive reports that it saved someone's copter.

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