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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    • Developer


           It's still quite a ways off.  I'd be surprised if it was ready any sooner than 6 weeks from now.  It will include a significant number of improvements however including the spline waypoints.

      • Randy, That's good to know then. Thank you for your reply.

      • Randy, will spline wp be manageable for APM 2.x, or is it PX/Pixhawk domain ?

        Moreover, is my hope that spline will improve follow-me behaviour misplaced ?

      • i hope it will be ready for sunny days(june will be a great  date to be release)

  • @randy, i am sorry. these logs were made keeping WP_YAW_BEHAVIOR as 1 . that' when the problem occurs. The problem does not occurs when the WP_YAW_BEHAVIOR is kep as 2 (default). i had mentioned in my earlier post vise versa. I have not tried  this param for 0 and 3 values. as i mentioned i do nt have any problem with value kept as 1 or 2 when i plan my mission only using  'Waypoint' commands even by keeping WP_RADIUS as 0.

  • @randy, pls find the log file attached when WP_YAW_BEHAVIOR was kept as 2. Yes u are right always i keep the WP_RADIUS as 0 for multicopter flights. BUt this issue is resolved when i change this value to 1 (default). also when i have mission with only 'waypoint' commands (NO Takeoff NO RTL) i do not face any issue with value of WP_YAW_BEHAVIOR kept as 2.

    2014-03-05 16-56.log

    • Developer


           Ok, it's interesting that that has an effect.  Setting the WPNAV_RADIUS to zero isn't correct though, it should never be lower than 100.  If you add a waypoint with a delay you'll find it gets stuck at the waypoint as well.

  • Hi guys!!!

    And about simulation?! any news?


  • @randy, i think there is a bug in AC3.1.2 when you change the value of parameter 'WP_YAW_BEHAVIOR' from default of 2 to 1 the RTL command does not executes. the craft would rises to the RTL altitude and would keep loitering there. similarly after executing 'takeoff' command it does not executes the following command and instead keeps loitering at the takeoff altitude. when i changed this value back to 2 all the problems regarding these commands were solved. but this bug does not effects the 'waypoint' command. took me one month to find this problem. i changed to different APM2.5 many times. i did not try other values which are 0 and 3.

    • Developer


           Thanks for looking into this.  Do you have a log file or two showing the problem?  it seems a bit unlikely because the yaw and altitude hold code is completely separate but we can still look into it.

           It sounds a bit more like the copter is unable to reach the target altitude for some reason.  It's probably hovering just below the target or perhaps the WP_RADIUS has been set to be really small?

This reply was deleted.


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