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 –


    • On RC5 that works fine ;o)



      • Hey thanks for your reply .
        Can I test to retract without arming for testing purpose ? Cause I have all connected and configured my ch8 but nothing happened on the ground. I haven't flyed with this new frame yet
        • Sure you can.

          As I have a Tarot650 Sport sitting in it's bag with gear up, the first thing I do when I connect a battery is gear down without arming.

          Also, the first thing I did was to connect the gear directly to the receiver to be sure it's working OK.

          I did had some problems, as the manual was nonexistant, but after I sorted that out, it was easy to set them with 3.3.

          • Ok, after more investigation, my brand new landing gear controler is simply death...

            Thanks you for your help, really .

            • maybe is something wrong with wires..

    • Yup, works great  for me :)  I'm using the standard tarot retract controller from the 650sport (which I believe also comes with most of their other current frames).  The only thing it doesn't do as advertised is to automatically retract the gear after takeoff, it has to be retracted by rc switch.  But it always deploys for me automatically when landing or rtl.

  • Developer

    Copter-3.3-rc7 should be available through the mission planner's beta firmware link in about an hour.

    We think this at least partially resolves the attitude estimation problems that Winston, RobertS and Peter Barker (on another thread) found.  Still, we recommend staying on -rc5 until we've had more time to be sure. We're pushing out this version because we believe it's safer than leaving a clearly broken -rc6 in place.

    If you do feel brave enough to test -rc7 please be on the lookout for attitude estimation errors especially in the first minute of flight.

    Changes since AC3.3-rc6:
    1) reduce EKF gyro bias uncertainty that caused attitude estimate errors
    2) force 400hz IMU logging on (temporary for release candidate testing)

    Sincere apologies for the troubles and thanks for helping us test so these types of troubles don't spill out into the larger community!

    • T3

      Hi Randy,

      I had two successful flights with rc6. The second however started a little strange: After arming and while still on the ground, the copter showed massive wobbles/oscillations - similar as with wrong PIDs. Then after disarming and arming again all was fine. Sounds like it is related. Send me a PM if you are interested in the log.

      Best regards,


    • Hi Randy,

      I guess I will be surprised if this is actually the source of the problem. I am running rc5 with close to these values (1e5 rather than 8e6 in GBIAS_PNOISE) and I don't see this massive oscillation. Here is a graph from wednesday with rc5. You can see that the overall changes are very small and the oscillation occurs around a mean that looks close to what you actually want. I suppose the increase in uncertainty could be the culprit (I didn't change the default), maybe the initial perturbation throws everything off? If it stop raining I might experiment a little to get more data.


      • So I ran tests with rc7 with GBIAS_PNOISE set to 1e5, 8e6 and 1e6 respsectively. I can't say that rc7 felt any different to rc5. The learned offsets looked pretty similar to what I was getting with rc5 and control seemed good.

        It was fairly gusty but the copter coped fine and the EKF innovations seemed ok. I couldn't see any difference in roll/pitch/yaw between DCM and EKF. The logs are pretty large because of the IMU logging so I won't post here. I guess a theory might be if you have high vibrations then you will be more susceptible to bad gyro bias learning.

        I did notice two unrelated things:

        1. You can't set GBIAS_PNOISE in tower, it thinks the value is effectively 0.

        2. I still see very aggresive throttle up with RCMAP. Spin on arming does not work for me and as soon as I touch the throttle the thing tries to take off.

        Graphs below. Let me know if you want me to plot anything else.


This reply was deleted.


DIY Robocars via Twitter
RT @DanielChiaJH: @a1k0n @diyrobocars @circuitlaunch And here's the final showdown! Video courtesy of @chr1sa I think I was a little faste…
22 hours ago
DIY Robocars via Twitter
RT @DanielChiaJH: @a1k0n @armand_dpl @SmallpixelCar @diyrobocars @circuitlaunch I use @foxglovedev Foxglove Studio for my visualization nee…
22 hours ago
DIY Robocars via Twitter
22 hours ago
DIY Robocars via Twitter
RT @a1k0n: @DanielChiaJH @diyrobocars @circuitlaunch Here's my car's view of that race. About 8.4 second lap times for laps 2 and 3... both…
DIY Robocars via Twitter
RT @DanielChiaJH: Great racing against @a1k0n today at @diyrobocars! Pretty cool to both break sun-9s at the track today I think I got very…
DIY Robocars via Twitter
Broadcasting the @circuitlaunch race live now at Races begin around 2:00pm PT
Oct 1
DIY Robocars via Twitter
RT @a1k0n: ran a huge number of hyperparameter tuning experiments yesterday; now I can train a new policy, far with better quality, in 15 m…
Oct 1
DIY Robocars via Twitter
RT @a1k0n: Did I get rid of hand-tuned parameters? Yes. Am I still hand-tuning more parameters? Also yes. I have a few knobs to address the…
Sep 26
DIY Robocars via Twitter
RT @a1k0n: I'm not going to spoil it, but (after charging the battery) this works way better than it has any right to. The car is now faste…
Sep 26
DIY Robocars via Twitter
RT @a1k0n: Decided to just see what happens if I run the sim-trained neural net on the car, with some safety rails around max throttle slew…
Sep 26
DIY Robocars via Twitter
Sep 24
DIY Robocars via Twitter
RT @SmallpixelCar: @a1k0n @diyrobocars I learned from this. This is my speed profile. Looks like I am too conservative on the right side of…
Sep 24
DIY Robocars via Twitter
RT @a1k0n: @SmallpixelCar @diyrobocars Dot color is speed; brighter is faster. Yeah, it has less room to explore in the tighter part, and t…
Sep 24
DIY Robocars via Twitter
RT @a1k0n: I'm gonna try to do proper offline reinforcement learning for @diyrobocars and throw away all my manual parameter tuning for the…
Sep 23
DIY Robocars via Twitter
RT @circuitlaunch: DIY Robocars & Brazilian BBQ - Sat 10/1. Our track combines hairpin curves with an intersection for max danger. Take tha…
Sep 22
DIY Robocars via Twitter
RT @SmallpixelCar: Had an great test today on @RAMS_RC_Club track. However the car starts to drift at 40mph. Some experts recommended to ch…
Sep 11