Copter-3.3 beta testing

Warning #1: an issue has been found with Tower's Pause button which can cause the vehicle to fly to an old position if the vehicle has not sent a position update to Tower in some time.

Warning #2: Copter-3.3.2 fixes a bug found in Copter-3.3.1's desired climb rate initialisation which could lead to a sudden momentary drop when switching from Stabilize or Acro to AltHold, Loiter or PosHold.

Warning #3: Copter-3.3.2 fixes an issue found in Copter-3.3.1 which could lead to hard landings in RTL or AUTO if the WPNAV_SPEED_DN was set too high (i.e. >400 or 4m/s) and/or the WPNAV_ACCEL_Z was set too low (i.e. <100 or 1m/s/s).

Warning #4: a bug was found in Copter-3.3 which could cause a sudden crash if you abort a Take-off initiated from a ground station.  Video description is here.  The bug is fixed in Copter-3.3.1 so we recommend upgrading.

Note #1: AC3.3-rc8 corrected a long standing bug in the HDOP reporting.  HDOP values will appear about 40% lower than previously but this does not actually mean the GPS position is better than before.
Note #2: if upgrading from AC3.2.1 the vehicle's accelerometer calibration needs to be done again.
Note #3: set SERIAL2_PROTOCOL to "3" and reboot the board to enable FrSky telemetry like in previous versions.
Note #4: the wiki will be updated over the next few weeks to explain how to use the new features

Copter-3.3.1 is available through the mission planner.  The full list of changes vs AC3.2.1 can be see in the ReleaseNotes and below are the most recent changes since AC3.3.

Sadly this version (and all future versions) will not run on the APM2.x boards due to CPU speed, flash and RAM restrictions.

Changes from 3.3:

1) Bug fix to prevent potential crash if Follow-Me is used after an aborted takeoff

2) compiler upgraded to 4.9.3 (runs slightly faster than 4.7.2 which was used previously)

Changes from 3.3-rc11:

1) EKF recovers from pre-arm "Compass variance" failure if compasses are consistent

Changes from 3.3-rc10:

1) PreArm "Need 3D Fix" message replaced with detailed reason from EKF

Changes from 3.3-rc9
1) EKF improvements:
    a) simpler optical flow takeoff check
2) Bug Fixes/Minor enhancements:
    a) fix INS3_USE parameter eeprom location
    b) fix SToRM32 serial protocol driver to work with recent versions
    c) increase motor pwm->thrust conversion (aka MOT_THST_EXPO) to 0.65 (was 0.50)
    d) Firmware version sent to GCS in AUTOPILOT_VERSION message
3) Safety:
    a) pre-arm check of compass variance if arming in Loiter, PosHold, Guided
    b) always check GPS before arming in Loiter (previously could be disabled if ARMING_CHECK=0)
    c) sanity check locations received from GCS for follow-me, do-set-home, do-set-ROI
    d) fix optical flow failsafe (was not always triggering LAND when optical flow failed)
    e) failsafe RTL vs LAND decision based on hardcoded 5m from home check (previously used WPNAV_RADIUS parameter)

Thanks for your testing!

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      • Hi, on friday 26.6. I updated from RC 5 to RC 6.

        I changed only the values P Pitch from 13.700000 after Autotune to P 9.740000 (the same value from Roll)

        The Hexacopter has FC Pixhawk 3DR, DJI motors 2312 with esc 420 S and lipo 4S 5000 mAh, time of flight was 12 minutes - without any problems !!!!!!

        Flight modes: Stabilized, AltHold, Loiter, PosHold, Circle, Land, RTL

        enclosed you find the logs 

      • report was doubled

      • Changed droneshare settings. Maybe now? I did change back. Btw, why p limit in mp is 0.2? 0.35 on mine seems to be ok..?

        • Developer

          Hi Kuisma,

          Rate D is limited at the lower end to 0.002.

          I think I see the problem.... maybe.... It looks like the release went out with AUTOTUNE_AGGR set to 0.05. This tends to be a little sensitive, the default should be 0.1.


          • Thanks for the tip. I changed aggr to 0.1 and did another autotune. Now pitch seems ok, but roll is still quite bad. Lot's of wobble and quite sluggish. Yaw feels quite aggressive but it works. Oh, when in stab mode and doing yaw, copter gained quite a lot altitude. This didn't happen in althold mode.

            new results:

            stab roll & pitch: 6.25, 10.95

            rate roll



            rate pitch










            Strangely lot difference in roll and pitch?


            pic of the quad:

            It's 700mm.

            • Developer

              Hi Kuisma,

              Yeh, roll is still messed up. The good news is your problem is specifically what the latest changes to autotune are designed to fix. (Rate noise during the test)

              To dampen down your Yaw control I would suggest turning on feed forward and using your acceleration parameters. A good starting point is:


              If the FF is set to 1 then Autotune will set them at the maximum your copter can handle.

              • Forgot to set those parameters, but tested autotune today with latest firmware. Now it seems to be working ok. Though I think controls are quite a lot softer than with earlier (3.2 or 3.1.5, don't remember which I used to tune it earlier) autotune version.

                this time I got











                • Developer

                  Hi VP Kuisma,

                  That is more like it.

                  Yes it should be a little lower in the D term and P compared to the old Autotune. The old autotune targeted a small amount of overshoot, the new one is targeting perfection. This should mean a slightly more locked in copter.... But we are really splitting hairs here now.

                  Thanks for the feedback!!!!

              • Leonard, this was something i was not knowing. Activating ATC and FF will be considered during autotune and set to max the copter can handle ? if it's so this is pretty cool!

                As i'm flying almost acro i haven't enabled ATC and FF but considered the benfits i'll give it a try....

                • Developer

                  Cool, Thanks Pomaroli!!

                  I will be very interested to hear your feedback!!

                  With the next autotune, I hope you will get a nice tune and close to maximum acceleration parameters.

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