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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So PaulA is correct in thinking there's more to it than just the GPS_HDOP_GOOD check.  The EKF has it's own checks that involve:

  • number of satellites is > 6 (this check is really redundant unless the HDOP_GOOD is set ridiculously high)
  • checks GPS vertical velocity is consistent with the inertial nav velocity
  • checks GPS reported speed accuracy

So what can happen is that even if the hdop values are low, the EKF checks may not have passed and we don't report that well.  It'll just say "Waiting for 3D lock" (or something like that).  That's a bit misleading and we should fix it.

BTW, if you're going to do a mission, it's best to first arm in Loiter or PosHold instead of Stabilize, AltHold or Acro.  This better ensures that the GPS checks have passed before you try to enter AUTO.  The failure tone you heard was because those checks hadn't passed when you switched from Stabilize to Auto.  I'm just saying you might as well make sure those test have passed while the vehicle is on the ground if you're planning to do a mission.

Evgeny, Jesus, Paul, Artem,

Well, I wouldn't have expected that!  I've heard of the PixHack but did not know it had built in anti-vibration isolated IMU.  It seems like a good idea but in this case at least it's performance is not good.  I'd recommend going back to the more traditional 3M vibration dampening foam.

Evgeny, we don't actually have a lot of vehicles with this level of vibration.  I was wondering if you could leave it in it's current configuration and test -rc9 when it's out in about a week (or maybe a little less)?  We're going to try one more idea to improve vibration resistance.  After that testing is done, I'd recommend using the 3M foam or something similar.

У меня оригинальный, купленный напрямую у производителя. Разбирал - там все надежно. Да и уровень вибраций IMU очень хороший (обычно я летаю с худшими вибрациями), а вот для IMU2 вибрации запредельные (я правда не уверен, что для него теже границы что и для MPU6000). Плюс у меня под Пиксом двусторонний скотч, но сверху еще стяжка, т.к. оставлять его просто на скотче стремно - он тяжелый, может при резких маневрах улететь. Сейчас делаю другой коптер на той же раме, но с антивибрационной развязкой, если поможет, то значит проблема в Пиксе, если нет - в софте.

Ok, I leave this frame for testing RC9. And now I assembling new frame same as previous but with anti-vibration platform and try to check in with AC3.3

Thanks for support.

I tried rc8 on my 250 size quad. Althold, poshold, loiter, rtl is ok. and also I have tried flip, everything looks good in my opinion

Only flip mode needs fine tuning on my 250 size quad

Thanks Randy !
So a green indicator on the PixHawk, while fence has been setup, isn't valid to assume you are good to go..

Taking off in any of the GPS assisted modes is a better check.
That is a kind of misleading I think, I.e green light should be good in all cases ?

So a combination of GPS being below the HDOP value, as I think number of Sats is specified with it's own indicator (default 6)
AND EKF initial values (while still on the ground) passing correctly should be used to present the green light on the PixHawk might be a better approach?

Just a suggestion...

I noticed with RC8 that after a while a get a fast flashing green light which would indicate low hdop I'm assuming.

I also found it a pain when scripting a number of missions that I needed to constantly switch flight modes because the copter would not arm in Auto Mode.  I was using Tower to quickly load different flight plans and just needed to have them run only to have to walk over to my RC transmitter and flip the switch so it would not be in Auto Mode.  I could have pushed a button on the tablet I suppose but it seem faster to flip a switch.


I was under the impression you couldn't arm in auto mode anyway, can't in 3.2.1 as it's designed that way.

I know but it would be nice if your just using a GCS and what to fly a number of missions that at the end of the mission it would switch back to Loiter or Stabilize once it lands so I can just lock and load.

Yes, the the fast flashing green LED is a good thing.  It means the GPS has SBAS so it's precision should be better.  We will definitely add this to the LED description wiki page before the official release.  Sorry for missing this in the release notes.

Yes, not allowing arming in Auto and not switching out of AUTO at the end of a mission are safety features to stop accidental takeoffs and to reduce accidents caused by the pilot not knowing what flight mode the vehicle is in.

APM planner 2.0.18 supports the AC3.3 params.

Насколько я вижу у тебя в пластиковом корпусе - это не оригинал. Там силикон намного жесче чем в оригинале. + IMU2 сам посебе немного геморой, но это отдельная история, он резонирует на других частотах чем первый. Загрузки 3.2.1 и попробуй полетать? Я бы не ставил 3.3 даже final, на машину твоего размера. У меня на 3.2.1 летает 7кг Y6 с GH4 на подвесе каждый день, четверик для ФПВ и трешка уже очень давно и без нареканий. 

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