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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    • Developer

      Hi Henri,

      Sorry for the slow reply. I have tried a couple times but couldn't do it as I only had my phone.

      This is the process I use when starting tuning a large copter. First up set these parameters

      MOT_THST_BAT_MAX,number of cells x 4.2
      MOT_THST_BAT_MIN, number of cells x 3.5


      Then set the control loop parameters to their defaults.

      In stabilize slowly increase your throttle until the copter starts to lift of the ground. Listen for any sign of oscillation and if you hear it be ready to shut down the throttle immediately.

      One of the things I find is if you are hovering lower than 30% then you will tend to have trouble with autotune. If you are hovering at a very low throttle position then add weight to get your copter up into the 30% to 40% range. If you are above that then no problems.

      Once you can take off safely then you can start testing small roll and pitch inputs. Keep the copter low so you don't do too much damage if you need to shut it down. I will tend to do this at around 0.5 m.

      If you find the copter reasonably safe then you can increase height to say 5m and increase the roll and pitch inputs.

      If you find the copter is a little wobbly (slow wobbles about as fast as you can say wobble wobble wobble) then increase the Rate D terms (you can use the slider set to go from 0.004 to 0.008). Just make sure you don't increase it to the point you get oscillations. 

      If you get oscillations then you may have a flexible frame or something like a gimbal that can move. If you are lucky you will be able to just reduce Rate D. I haven't seen anything that oscillates on the stock PID settings.

      This should get you flying. Then you can build up your roll and pitch inputs (30 degrees) to the point where you feel comfortable running auto tune. If you don't feel comfortable you may need to do a manual tune before you can run Autotune.

      Hope that helps and sorry for the delay!!!!

      • Hi leonardthall.

        Thank you very much for your help. Ecalc software "said" that hovering should be around 45 to 48% throttle. (8S 10A) giving a possible 4 to 6 minutes flight. So hopefully should go ok. I'll follow your directions.

        On a different subject:

        Still with 3.3 RC5:

        Following a successful autotune on a 1 meter (axis to axis) hexacopter,  storing values after completion of auto tune indicated on mission planner (one axis at a time). everything looked great. Did first roll then pitch and finally yaw. This last one took really a long time.. 

        Anyway few days later wanted to take off and aircraft was really jerky, short wobbles, and it was really hard to see if it was in the pitch or roll axis. Diminishing the D value a bit at a time did sort of "calm down" the beast but I couldn't work out why it did change so much. (From a fantastically stable aircraft in the air just at the end of auto tune to a nervous wild jerky beast)!

        Just thought I let you know as something changed in between without clear reason.



    • The default PID's are normally pretty acceptable to get you in the air on your maiden.  Have you experienced any problems with the settings?

      • 3702705392?profile=originalWell it depends which "default" one selects from mission planner. 

        I guess PID are very different depending upon weight motors prop size and shapes etc...

        So I would have like to get some "possibly working PID" for the model I did mentioned. (Heavy H shape aircraft).


        • What is the default setting and wich to choose for Tarot FY690S ?

          Any help on this are welcome ;-)

        • You shouldn't need to touch those when starting out.

          The tunable parameters for flight are on the "Extended Tuning" tab.  Their default value should get you a reasonably stable take off. You may need to slightly tweak to keep it stable, but it shouldn't be far off 

          The challenge with sharing PID's is they're based on a myriad of factors which don't typically replicate when DIY'ing a model.  In your case, you are flying a very large and heavy craft with an indeterminant frame, motor, ESC and weight balance combination.  If I don't have all of those the same as yours, my PID's -- particularly having been tuned and therefore very specific to my craft -- are likely to be a risky proposition.

          TBH, this quad is a significant investment and I'd caution against running beta firmware before you've tested with a stable release.

  • Dont know if this belong here....i have this hex with rc5. Almost tried all 3.3 rc's, but hasnt done much flying. Just waiting for release.

    Anyway, today i was trying to calibrate a attopilot and locked the hex down to prevent lift. In stabilize mode the pixhawk throttled up ALOT by itself after i gave just around 5-10%, like if i have raised throttle slowly to nearly full.  Throttling down again was possible. Tried several times and it was the same. In alt hold the throttling was normal. Thought of trying to fly in stab mode to see if it happened then, but found it to risky. 

    Is there a parameter that can cause this? Have weighted it down before many times and it wasnt like this, throttle was normal.

    All is calibrated. transmitter in missionplanner, esc's, compass, accel..


    • I think I had same and I concluded that program feeds input to motors, does not see response from a barometers and feeds even more input to motors to increase lift. Is it a logical assumption?

      I tried to fly mine in stabilize mode and it did not get anywhere, if that matters.

      • eh, maybe if it had a plan to go somewhere on its own :) dont think it knew i put rocks on its feet, haha

        Maybe if there was a mission and it should reach a certain height, but not in stab mode, i cant imagine...

        You mean you couldnt take off?

        • sorry, bad choice of words. did not get anywhere = it means it did fly fine and did not fly away from me.

          stabilize mode worked fine. no issues. I have different problems - failsafe RTL, controls invert in super simple mode, etc.

          I posted logs here about them.

This reply was deleted.


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Aug 25