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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  • I realized a very bad autotune with both rc7 and rc8

    The frame is deadcat style/V-style. So I started with iris+ parameters as preset. And it was flying ok. Seemed a little agressive. 
    Tried autotune. Roll tune happened within 2-3 minutes. But pitch took a very long time, more than 10minutes I guess. Yaw also completed quickly. When I look at the tuned parameters, I think roll and yaw parameters are in acceptable range and probably good. But It was so difficult to fly with this new PIDs, I could't test how good they were. With these new pids its pitch was uncontrollable. A screeshot of PIDs after autotune is attached.


    • Developer

      Hi Pritam,

      That is definitely a terrible tune on pitch!!!

      Do you have a log?

      I would suggest resetting your pitch parameters and redoing the pitch tune. You may need to increase the aggr to 0.1 for pitch. You can do just the pitch by setting the Autotune_axis to 2.

      Sorry for the slow reply!!

    • I've had the same thing, low pitch stab and PID values from rc7/rc8 autotunes.   Your PIDs don't look to bad, you could try increase the stabilize and see if it's better?  Also your IMAX numbers are low, I think these were increased significantly in recent RCs.

    • Developer


      If you have a look from when the AutoTune was performed Leonard can probably take a look.

  • Please taka a look at my log's.

    It's RC7, and since 3.2.1 I have frequent EKF errors....
    Is that because of the magnetometers differences (with Gyro/GPS) ?

    Recently my copter's turned off motors while in stable at altitude 120m (no logs attached:().
    Logs showed that there was EKF nav problem again (error 16 as I remember).

    You've said that it's fixed in RC-6/7. I doubt then...
    • Developer


      The problem is probably caused by very high vibrations.  Below is the output of the VIBE message which shows the vibrations are up above 50m/s/s and clipping of the accelerometers is also happening.  So not sure what vibration isolation system you're using but I'd recommend the 3M foam.  Feel free to post a picture of how your flight controller is mounted.


      • Motors and props are perfectly balanced. FC is mounted by using thick 3m foam, exactly.
        When FC replaced by naze32 , copter is flying briliant. Are you sure it's vibrations?
        Please look at the magnetometer data... MagX for example. For me it could be caused by electromagnetic interferences - as problem is happening mainly in one place...
        With rc7 copter is wobbling-in comparing to rc5. No autotune has been done since rc5.

        • Developer


          The VIBE message is pretty definitive about the amount of vibration.  I'm not necessarily saying it's the only cause of the EKF-Check errors but the vibrations are very serious it would be best to resolve that issue first.  The levels are about 3x what my IRIS produces and in the same range as the Evgeny logs in which the vehicle lost attitude control.

          We are working on improved vibration resistance for -rc9 but in any case, these vibes are pretty serious and should be taken care of.

          • BTW, had another crash copter on 3.3-RC8. It's Pixhack too. 

            It's quad V-tail. Fly good in stab and Althold but after few minutes its made crazy and go to ground in angle ~45 rgad.

            Log in attach. I think this because high vibration too.

            Still wait for RC9

            2015-08-03 17-47-11.bin

            • Yes, extremely, extremely high vibrations on that one.

This reply was deleted.


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