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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      • Thanks for developing!

  • Developer

    Copter-3.3-rc12 is now available through the Mission Planner's beta firmwares link.

    Desperately hoping that this is the final release candidate.  We received some complaints from others on the dev team that they were seeing a "Compass Variance" pre-arm failure which they could never get rid of without power-cycling the board so -rc12 has a change just for this one issue.

    If all goes well we will do the "soft release" of Copter-3.3 no later than next Tuesday.

  • Hi all,
    On page 320 of this thread I have left a post with an issue I had.
    Would there be any kind person who could take a look at my log file and help me understand problem I encountered?
  • Today I had a bad crash with RC11:

    I was flying smothly near to the ground. Suddenly the copter went wild going fast forward then left backwards. My control inputs did not respond to the Copter. So I shut down throttle, setting it with the camera on the ground. The objective of the camera is now destroyed, and some scratches on the display. I did not know what happens. Maybe someone could assist?

    (2015-09-21 14-54-28_crash.bin)


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    • Developer

      Gregmann,Ok, thanks for the log and sorry for your crash.  As Leonard says this one is a GPS glitch - the logic for that is now in the EKF so PaulR also helped with the analysis of the log.  Some of the bits we discovered:

      • the GPS update rate dropped from 5hz to 2.5hz 19 seconds before everything started to really go wrong so there was some early indication that the GPS was having troubles.  It's unclear why the GPS update rate slowed, it could be a GPS power problem, I'm not really sure.
      • the GPS suddenly lost lock completely for 6.4 seconds which is unusual.  We'd expect it to jump around or report bad positions but to suddenly lose lock is a bit odd.  I will ask Michael DuBreil (our GPS expert) to look into this.  I worry that the GPS driver may have actually caused the loss-of-lock as it tried to speed up the GPS again.  That's completely a guess but something we will look into.  Another possibility is that whatever caused the GPS to slow, also caused it to lose lock.
      • The EKF handled the loss of lock fine, it was when the GPS recovered that everything went bad.  There are some things we can do to improve this:
        • EKF will tell the position controllers (i.e. Loiter) that it's glitched so the Loiter controller will reset it's position all at once.  This may have avoided some of the vehicle leans you saw as the Loiter controller tried to move back to where it was before the glitch.
        • add a GPS Glitch failsafe.  We need to discuss what the response to a glitch should be but Solo guys have chosen to switch the vehicle into AltHold mode until the Glitch has cleared.  We might support multiple responses like we do with other failsafe.

      • Randy, Thanks for reply.

        In my opinion it looks like the glitch detection feature is not completely implemented.

        Its a nice feature that the controller detects a GPS glitch, but when the situation ends up in a crash, there should be another handling for this situation in the 3.3 code.

        Maybe there are some changes in the EKF part possible that leads to the same behavior as I saw with other EKF issues i saw in the past (switching to Alt hold, beeping, blinking, maybe this could only be overrided if switching to alt hold and then to another mode so that the the copter did not automatically goes back to GPS).

        For 3.4 it would be fine if there is a GPS glitch failsafe.

        Hopefully there is a chance to make the 3.3 more safe in GPS modes.



      • Having suffered a lot of GPS signal lock losses I'm going to have a look at my logs from Sunday. I was operating in Alt Hold mode most of the time so I may have dodged the same issue here.

        I like the drop into Alt Hold mode on GPS glitch and having multiple options would be ideal

    • Developer

      Hi Gregor,

      I am very sorry to hear about your crash and damage!!!

      This is a GPS glitch by the looks of things. I will need to talk to Randy about what happened here but it looks to me like you had a short GPS glitch that wasn't long enough to throw you out of Loiter but when the GPS came back the errors in the GPS position caused the copter to suddenly adjust itself. It looks like the copter would have settled itself quite quickly.

      I always recommend switching to Stabilize in any situation resembling what happened here. Stabilize gives the pilot the best hope of recovery and also gives the pilot the most direct control over the throttle and therefore the ability to kill the flight or attempt a controlled descent.

      I will chat to Randy and see if there is anything else we can tell you.

      Again, sorry to hear about your crash!!

      • Hi Leonardt,

        I thought when moving the Copter in Loiter, it is nearly the same as stabilize. Only when the sticks released its using its positioning features. But I think I was wrong.For the future I will program a switch for emergency (stab mode, landing gear). I was unable while trying to prevent a crash to the trees, dialing a 6 pos dial of the FrSky.

        It would be very nice to get some other suggestions about how to prevent fast autonomous movements in GPS modes, because the manual rc overrride seems to be no solution.

        • No, Loiter mode is fully automated controls all the time. Stick inputs are demands for measured acceleration/velocity, not lean angles such as in Stabilize.

          Yes, you are correct, that mode switch knobs are a poor choice as it's very difficult to get the mode you want quickly in a panic.  Heck, it's difficult even at the best of times.  Having a mode like Stabilize on a panic switch would be a good idea, but will probably require a complicated mix in your Tx.  One option would be to put Stabilize at the extreme end of your knob, so that all the way counter-clockwise was Stabilize.  Then you just grab it and turn it till it stops.

This reply was deleted.


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