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!

You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –


        • Wow... that's not just a minor glitch. Thanks for the info. 

  • Hello,

    i have a small tri running 3.3.2.on a pixfalcon. Flying in stabilize or pos hold there is always a small drift in yaw. Even when i keep the stick centered, it slowly turns.

    Looking at the logs i found that the DesYaw also drifts and the tri follows quite well. Where does this drift in DesYaw come from?3702178654?profile=original

    2016-02-02 16-13-35.bin
    • Developer

      By the way, Leonard's done some work on the TriCopter "stability patch" for Copter-3.4.  It has a number of improvements including reduced throttle-vs-yaw coupling and better prioritisation when it hits the upper throttle limits meaning you should get better maximum vertical acceleration.

      We have a bit of a shortage of TriCopter pilots so I hope you can help us test when the Copter-3.4 beta becomes available.

      • Developer

        HI Hubertus,

        One thing I forgot when I was talking to Randy. I dropped RATE_YAW_FILT_HZ to 2 Hz and that made all the difference for my tri. So I would suggest trying that first.

    • Developer


      One answer is the desired yaw can be dragged around by the actual yaw if it strays more than about 10 degrees.  There's some argument about whether that's too small an error to lead to the dragging but.. in any case, that's why you're seeing the desired yaw drifting.

      I had a chat with Leonard and we think it's primarily a tuning issue.  If we can get the control better then the desired vs actual will stay closer together and the dragging will stop.

      It looks like the tail servo is oscillating (see blue line below).  Leonard suggests reducing the RATE_YAW_P and RATE_YAW_I by 50% and keep doing that until the oscillations go away. RATE_YAW_P is already low at 0.08 but try even lower like 0.05.  RATE_YAW_I is currently 0.015 so maybe try 0.01.

      He also suggests keeping STB_YAW_P low (it's 4.5, don't raise it).


  • Hi, I get the bad accel health quite a bit in the colder weather. I've read Dmitry's thread and I'm not sure its the same problem as the sensors discharge issue. I see good data from the imu2 accelerometers when indoors, then I take it out where its cold and within 5 minutes imu2 goes bad. Then I can bring it indoors again and it'll start working. I've disabled the prearm checks for INS (then tried disabling all of them), and also have ins_use2=0. If I can manage to arm, it flies fine. But getting past that hurdle is sometimes difficult. I've found a workaround, to power up inside where its warmer then take the MR outside and arm/fly before the lsm303d goes bad (but sometimes this is difficult as the GPS needs a minute or two to lock in). Is there any way to disable the bad accel health warnings and ignore the lsm303d completely besides downgrading to AC3.2.1?

  • Randy / devs

    Is 3.4 gonna be released for testing anytime soon or is that sort of in flux? 

    • Developer


      The motors rework has taken a little longer than expected which is why Copter-3.4 hasn't begun beta testing yet.  There's also another important decision that needs to be made which is do we include any/all of these features in Copter-3.4 or push them off to 3.5?

      • Terrain following
      • Precision landing
      • AP_Arming consolidation with Plane/Rover (this will produce better pre-arm check reporting to the ground station allowing it to display a single full list of all checks that are currently failing)

      I'd say each one of these features will consume about 1 extra week of dev.

      • I'd have to say I'm highly motivated to test out any feature for terrain following!  I've got a few laser altimeters, but open to trying new sensors as well. 

      • take the week + to get it right. Pushing out new versions for the sake of pushing out new versions is never a good thing. Take the time to write it correctly. 99% of us can wait a few weeks before a new version. I personally would rather wait a few months and get a well written code base then to have these things churned out week after week and having to deal with any issues that arrive with them. I'd go so far as saying a new version every 6 months is almost too much too fast.

        That's not to say bug fixes could not be released on a fast ring, but I'd much rather see new "versions" released on a much slower and defined "slow ring" :)

This reply was deleted.


Gremsy liked Gremsy's profile
Mar 12
DIY Robocars via Twitter
RT @chr1sa: Donkeycar 4.4 released with tons of new features, including path learning (useful with GPS outdoors), better Web and Lidar supp…
Nov 27, 2022
DIY Robocars via Twitter
RT @NXP: We are already biting our nails in anticipation of the #NXPCupEMEA challenge! 😉 Did you know there are great cash prizes to be won…
Nov 24, 2022
DIY Robocars via Twitter
RT @gclue_akira: レースまであと3日。今回のコースは激ムズかも。あと一歩 #jetracer
Nov 24, 2022
DIY Robocars via Twitter
UC Berkeley's DIY robocar program
Nov 24, 2022
DIY Robocars via Twitter
RT @chr1sa: The next @DIYRobocars autonomous car race at @circuitlaunch will be on Sat, Dec 10. Thrills, spills and a Brazilian BBQ. Fun…
Nov 24, 2022
DIY Robocars via Twitter
RT @arthiak_tc: Donkey car platform ... Still training uses behavioral cloning #TCXpo #diyrobocar @OttawaAVGroup
Nov 20, 2022
DIY Robocars via Twitter
RT @emurmur77: Points for style. @donkeycar racing in @diyrobocars at @UCSDJacobs thanks @chr1sa for taking the video.…
Nov 20, 2022
DIY Robocars via Twitter
RT @SmallpixelCar: Going to @diyrobocars race at @UCSDJacobs
Nov 8, 2022
DIY Robocars via Twitter
RT @SmallpixelCar: Race @diyrobocars at @UCSDJacobs thanks @chr1sa for taking the video.
Nov 8, 2022
DIY Robocars via Twitter
RT @PiWarsRobotics: Presenting: the Hacky Racers Robotic Racing Series in collaboration with #PiWars. Find out more and register your inter…
Oct 23, 2022
DIY Robocars via Twitter
RT @Hacky_Racers: There will be three classes at this event: A4, A2, and Hacky Racer! A4 and A2 are based around UK paper sizing and existi…
Oct 23, 2022
DIY Robocars via Twitter
Oct 23, 2022
DIY Robocars via Twitter
Oct 19, 2022
DIY Robocars via Twitter
Oct 18, 2022
DIY Robocars via Twitter
RT @NeaveEng: Calling all UK based folks interested in @diyrobocars, @f1tenth, @donkey_car, and similar robot racing competitions! @hacky_r…
Oct 13, 2022