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
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!
What are the red motor mounts made of? It looks to have broken off at a narrow point. Consistent with hitting the ground, of course, but also where I might expect failure under sudden strain of full-throttle. Speculation.
Speaking of speculation - where was the black cat at the fateful moment?
Any motor mounts of mine that have failed (or needed replacement because they were at risk of failing), did so at roughly that same location - where they join the arm, often via a stretch of material that is narrower than the rest of the mount. Even worse, manufacturers compound the problem by cutting material out of the mount nearby, further concentrating the stresses. I guess it looks cool.
It begins with stress-weakening, barely visible (maybe just a local discolouration), then hairline cracking (still easy to overlook), then sudden, catastrophic snapping.
I make my own mounts now, and I avoid that narrowing phenomenon entirely. It's trouble.
Ok. But given the sudden chaos in the video (and 200 feet away!), your eyes work much faster than mine.
Here's a useful video on why motor mounts fail roughly where yours failed:
(you can skip the first 5:50 entirely)
Motor mount 'stealth' fatigue is a serious hazard.
Where is your other posts on this? I assume you have a log of autotune somewhere.
Sorry, I have distracted for the last week or so. The main problem with your autotune is the active breaking tends to need a low rate D but your AUTOTUNE_MIN_D is set to 0.004 when it needs to be set to 0.001 for a small quad like this.
As you have already discovered, you will need to manually set ATC_ACCEL parameters if you tune manually. Autotune does this for you during a tune based on measurements it makes.
It also looks like you may not be tuning in very calm conditions. This can mess up autotune on small quads quite badly.
I have to do some back to back testing of active braking vs non-active braking on my quad to see how much it improves things when using autotune.
Your vibrations are pretty high. Large props into the wind can vibrate a fair amount especially if the frame is flexible. Your tune doesn't look like it is causing the problem though.
Well about 18 or so multi rotor builds over last 6 years and I find they don't all do this my friend. It doesn't happen with my NAZE32, APMs, Openpilot Revo, DJIs and so on. I have only had this happen one time ages ago, but cant remember now why and which FC it was and then how I fixed it.
If what you say should be true, it should happen in every case then? So then why doesn't it happen if I unplug the battery when it is "armed"? Yet when it is put into safe mode the motors go "stiff" after 5 seconds and then stay stiff after I unplug the battery.
I would assume if the caps are doing this then they would do it constantly armed or disarmed? Why is it that when armed they are not and when disarmed and put back into safe mode, after 5 seconds they go stiff again? I would have assumed once put into safe mode, nothing should be going to the motors or the ESCs caps? Yet they are?
This is a Pixhawk fw issue I think.
It has ALWAYS done this on every one of my multirotors. From back when I started using the early miltiwii boards, all the way up to my hawks. Here is a pretty good explanation why.
When the safety button is solid there is nothing being sent to the esc's. I bet if you pull the esc out of the pixhawk while everything is powered up you will see the same thing. This is what your ESC does and has nothing to do with the pixhawk.