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!
Replies
A shot in the dark maybe but this kind of unstable behaviour could be due to a too soft anti vibration/ dampening of Pixhawk. How is your Pixhawk held on the frame?
On the mount like that:
Not sure whether it's too soft. What do you think?
Those dampers look way too close-set to me. It will cause the controller to wobble and definitely cause problems.
Thanks for your reply.
I use only bottom plate of the mount posted above - another set of holes for dampers are in the carbon frame's plate itself. They are about 45x45mm. It's definitely not a pixhawk size, although it used to work on AC 3.2. Could it be an issue on AC 3.3?
Did you look at the EKF while it was in the air? At first glance the vibration levels don't look bad despite the clipping, so maybe the following is a waste of time, but is my experience with knocking vibration down. However, I would think with your setup hard movements could cause wobbling and weird IMU behavior. OTOH I could be totally wrong.
On a quad with not a lot of real estate to mount stuff, I ended up doing this, which resulted in very low VIBE levels. It has a AUAV-X2 secured with 3m tape, but has had a Pixhawk. Another thing is 4 10-12mm squares at the outer corners seem to isolate vibrate best. HK Orange Latex is very good and you get a lot for <$2. I think it may even work better than the 3DR foam which isn't available now. Rubberized cement holds well.
I also found that mounting plates that look like swiss cheese do not bode well. On this copter was glued a thin piece of aluminum plate to give a solid surface on a pretty flimsy CF plate with lots of holes. Without that vibrations were marginal. With it, nearly nothing. Rarely do I mount directly to the top plate unless it is solid. The Pixhack is a nice product btw.
On this one with a Pixhawk I used 4 Plexiglas pieces mounted on the top plate using 3M 10lb tape. It's thick and helped isolate vibration. This picture was taken when it had 3DR foam, but now has the HK latex.
Hi John,
sorry to see your crash!!
Can you please provide a log of the flip and a couple of photos of your copter.
This is how you need to tune your copter.
Reduce Rate P, I, and D by 25% at a time, from defaults, until your copter is stable.
Increase Rate D until you start to see oscillations.
Reduce Rate D until you don't see oscillations
Increase Rate P until you see oscillations
Decrease Rate P until you see oscillations
Set Rate I equal to P
Check to make sure your copter is stable when quickly rolled and pitched to 45 degrees and the stick is let go. Don't hold the stick to build up speed, this test should be done as quickly as possible.
If the copter passes this test perform Autotune on each axis.
Logs: http://1drv.ms/1MPxlJ5
First file - P value tuning. Second one - more about I value tuning.
Photo: http://1drv.ms/1PuM8I2
The only difference is that GPS is put on stick now (the same location, but on stick).
Hi John,
I would suggest changing
INS_GYRO_FILTER to 40
and
RATE_ROL_FILT_HZ to 40
RATE_PIT_FILT_HZ to 40
Let us know how you go.
Thank you for your help, I'll try to apply the strategy that you proposed.
Just a quick question. What did you mean by the following?
Check to make sure your copter is stable when quickly rolled and pitched to 45 degrees and the stick is let go. Don't hold the stick to build up speed, this test should be done as quickly as possible.
Should the quad withstand when I do the same but speed it up significantly first?
So much has changed since 3.1.5 and I forgot so much since 3.2.1
I'm sure it's been discussed and answered over and over, BUT, if after Auto Tune the copter seems to not hold well in slightly windy conditions, should AUTOTUNE_AGGR be increased or decreased. I did it at .07.
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