Help for a beginner: flyaway in stabilize mode

Hi Guys,
I’ve had a couple flyaways now with my Mini APM 3.1 in my custom quadcopter.
I’m not sure what to make of the log files. There appear to be references to problems with the compass, but I’m not sure what are “normal” errors, and what are “real” errors.
I think it has something to do with when the battery gets a bit low. The failsafe doesn’t seem to kick in properly, instead, it just hangs there in the air, or spins out of control and crashes.
I have tested that the fail-safe is set properly and that it does, indeed land properly when I shut off my radio.

I’m quite a beginner, and could use some advice from the pros. :slight_smile:

Please let me know if there is more info that I can provide.

I am at best an intermediate uav person, but have some experience with logs.

My comments:

  • your GPS HDOP is high to start with, then goes much higher when you get a GPS error. Check GPS wiring, GPS mounting, and make sure you let the quad lock well (a few minutes at least) before taking off
  • it is not a good idea to run the battery down and let the quad failsafe kick in. I use one of the $3 LIPO monitors on my APM quad and when the alarm goes off, I land it myself immediately. You are trusting too much in automation and battery technology IMHO.
  • you are getting a lot of barometer errors. Don’t fly with a bare APM card, make sure the APM is packaged and some people recommend putting a little foam rubber on top to make sure the barometer is not confused by the prop wash

Hopefully you will get someone more expert to reply, but that is my 2 cents, FWIW. Good luck and happy flying.

The Mini APM a clone bare board in most cases so will need covering with a little foam.

Here is an Auto Analysis of your dataflash log:

Size (kb) 1124.7158203125
No of lines 15836
Duration 5 days, 14:46:46
Vehicletype ArduCopter
Firmware Version V3.2.1
Firmware Hash 36b405fb
Hardware Type
Free Mem 0
Skipped Lines 0

Test: Autotune = UNKNOWN - No ATUN log data
Test: Balance/Twist = GOOD -
Test: Brownout = GOOD -
Test: Compass = GOOD - No MAG data, unable to test mag_field interference

Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = FAIL - ERRs found: FS_BATT GPS_GLITCH GPS
Test: GPS = FAIL - GPS glitch errors found (4)
Min satellites: 0, Max HDop: 99.99
Test: IMU Mismatch = UNKNOWN - No IMU log data
Test: Parameters = GOOD -
Test: PM = GOOD -
Test: Pitch/Roll = FAIL - Roll (-69.58, line 14637) > maximum lean angle (45.00)
Test: Thrust = GOOD -
Test: VCC = GOOD -

As was said above, you definitely had a GPS failure where the sat count went to 0 and the HDOP to 99.99 which is a really bad situation and probably resulted in the flyaway.

Thanks so much for the replies!
All of these things make sense to me, but what is confusing is that I was always in manual (stabilize) mode and wasn’t running a mission/using waypoints. I wasn’t using either GPS or BARO at the time. Could they still be to blame?

I believe stabilize uses barometer and GPS inputs.

As far as I understand, stabilize does “not” use GPS or barometer. Being new to this stuff, I’d recommend watching all of the videos on the link below. Painless360 has some good stuff.

ahem. so, um… looks like I had RTL set for the low-battery failsafe in mission planner. OOPS! :astonished:
I had assumed that the receiver failsafe would happen, and didn’t check the one in MP. Lesson learned! Thanks folks for your kind help!