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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I bought the Pixhack for something different. It has internal IMU dampening. Their early versions were not so great, but I have version 2.1 (2.8 is latest). I have no idea how they track the revisions, but there are no versions between 2.1 and 2.8!

Yes, the vibrations are fantastic, so thus far I can say their design appears to work well, but ordered some foam from HK just in case.

I need to know what PID or other parameters to adjust to remove the slight wobble at hover before doing AT. Experience tells me not to do AT unless the copter is stable and good vibration levels. I at least have one part good.

Doesn't look like this vehicle actually flew so I don't think we can trust those Vibe numbers.  Sorry!

I can assure you it did fly. I can also assure you I used the wrong file. What a dope, will try again tomorrow since I cleared out the logs.


It's not clear that switching to the internal compass would help and it's likely on some vehicle it would make things worse.  The gyros drift but the drift is quite slow so even without the internal compass, the heading could remain fairly accurate (i.e. within 30 degrees) for a minute or longer.

The logs were still on the pc. I guess with the Lions winning today my exuberance deluded me to think I loaded the correct log. So much for fantasy vibration levels.



 thank's for comment, now I know that isn't only my problem, (worse with simple mode) , I'm only flying near me now, to tune, check all things, etc. (...anxious) because I notice that, this week I have to pick up my new gps-ext compass and perhaps it's better to disable the int one.

PD: But I notice too, that this issue is much less with the pix and 3.3 than the 3.21 and APM


Ok, yes, so about 2x or 3x the levels on my IRIS.  We think things go bad when the vibe levels are over 60m/s/s so it'll probably fly ok.

Now much sense, I'm near that kind of graph, you scared me ;)


Really sorry for the crash.  I'm sad to say this looks like either a bug or missing sanity checks somewhere in the follow-me processing code.  We actually saw this once during beta testing of Copter-3.3 and although we couldn't find the exact cause we did add more checks and it didn't happen again (until now).  I will try and find other ways this could happen and come up with some more checks.

Can you tell me which version of Tower are you using?

EDIT: sorry, I see you've said you're using Tower version 3.2 which is the latest.


If you happen to have a tlog from Tower itself that might also help us track down the cause (although we will look hard in any case).

Randy thanks so much for looking into this.
Yes I am using the latest 3.2 version of Tower.
I was flying many, many times in FollowMe along with 3.2.1 w/o any issues.
I am also using quite often FollowMe with Tower and Solo (FW 1.2) w/o problems.
So this was a quite frightening experience seeing the motors going to stop all of a sudden and the drone crashing just 3 meters away from me.

How can I extract the Tlog from my Android?
Hi I flew yesterday in guided and follow me leash and face me only problem I had it faced the other way
Using 3.3

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