Hi all,
I need some help interpreting the attached log file.
Scenario :
I was flying my Arducopter Y-6, (What a machine, by the way!)
APM 2.6
AC3.xx
Stock hardware, no mods or changes.
5300mah 3S Lipo
Took off, flew around for about 30 secs, hit LOITER at about 3m Height. Held perfectly.
Throttled up, climb out to about 30 meteres, still in LOITER.
Hang around at this altitide for around 2 minutes, slowly yawing left and right to get some nice camera shots.
SUDDENLY, no power, ALL the motors stop, and the copter falls to the ground tumbling from about 20 meters up. During the fall I changed to STABILISE, and applied full throttle, nothing.
Amazingly only damage is one broken prop, this is one tough bird!
Now I have tried to decipher the logs. I have checked the following graphs:
VOLTS - battery was 12.4 at full , dropped quite quickly, but never below 11V
Satts - 7 satellites all the time, HDOP 1.8VCC - 5.0 to 5.5 V all the time, so no brownout on the APM
the only funny I can see is the graph of Throttle in vs throttle out, As the motors quit, the throttle out goes haywire, but no indication WHY.
I think perhaps I just dont know where to look..
Any Ideas? Any help will be greatly appreciated.
Wessie
Replies
Ok so went out today to do further testing, and finally I have a reproducable crash.
I destroyed 4 sets of props, but I can now make my copter crash at will.
I tested STAB, LOITER, and RTL today, all work great, even LAND is 100%.
To make the copter(y6) crash, I put it in loiter, then yaw hard left.
The copter banks right as it yaws, flips over , and crashes. EVERY TIME. I immediately put new props on, and it flies 100%. In STAB mode I can do some quite serious high speed flying and hard banking maneuvres directly after a crash, so i have pretty much ruled out hardware failures..
As this point I have narrowed it down to:
1. A funky problem in the y-6 code, or
2. Some PID settings (mine are all pretty much default) that may be too agressive still, or
3. A bad connection on a ESC
Got home and started stripping the Copter, and RE-checking all the bullets and soldering to the motors, found nothing funny .
I wish someone out there , who has a y-6, would yaw hard in loiter, to see if it does the same. At least then I can rule out the code issue.
Will keep at it, I MUST get to the bottom of this one. Any suggestions welcome.
UPDATE :
So one week later, and some serious flying and checking EVERYTHING after the crash, I think I have pretty much ruled out Hardware failure.
After the crash, I replaced two propellors, and have been flying since. same hardware, same software, same pids.
Unfortunately looks like this will be one of those frustrating ones where the cause will never be known.
My guess? I think that a gust of wind may have put the craft at an akward angle in LOITER mode, and the APM lost the plot. I may of course be wrong, so I will go down that road in a new thread.
Thank you to everyone for your help and advice.
Hi Wessie,
yesterday I had similar problem - one channel (roll) got crazy for a second and quad fliped in roll. It was just during takeoff and only
one proppeler is broken. But it scaried me since latest versions of ACM didn't surprise me this way.
When I checked logs, only the roll channel changed value for a moment, others left OK. From this i deduce there was some problem with PPM encoder on my APM v 1.4 unless i did it manually on my RC TX, but i didn't.
Moreover I'm using FrSky with telemetry and it didn't give me any alarm of missed signal
Note that have lodade latest FW version of PPM encoder.
Here is the screen shot of the attitude and ThrIn, one can see it at point 940 where RollIn (red line) went suddenly down.
RC TX - futaba FF9 + FrSky DHT-U
RC RX - FrSky D8R-XP
APM v. 1.4
ACM 3.0.1
2013-08-09 15-34 1.log
Hi Wessie,
Not too sure if this relates, but........
The Quad I bought lately, suddenly tonight had a problem after I loaded the latest code.
I erased, reloaded, re- configured, programmed ESC's numerous times, but the right front motor just did not want to run.
I kind of narrowed it down to the ESC, and wanted to replace it with a spare I had, but the bullets were different, so I had to use the ones from the "faulty" ESC.
Long story short, after cutting off the heatshrink, one bullet pulled off the wire lead with very little force, never was soldered properly :-(
I re soldered all three bullets and sockets, problem gone.....
Going to have to check the other three ESC's.
So glad this happened on the ground.......
I had the same problem with my 3dr apm 2.5 running 3.0.1-rc5 850kv 20a esc 10x4.7 with 3s 3300mah setup. I had a bad crash broke all the legs so i ordered new esc from hobbyking the f-30a blue esc and reflashed them with SimonK firmware and upgraded to 880kv motors and 11x4.7 props I still had the problem happen except i pushed the throttle and it caught itself and flew up and I landed it so i got luck that time. I have the same problem and I ordered 4s 3300mah battery hoping that maybe the battery failsafe subsys error i was seeing in the logs and I don't fly the batteries below the POSTED through-out DIYdrones post i have read for couple of years so I am not new to this either. I will report back whether the motor cutout happens with 4s or not as I am having the same problem and still couple of weeks into researching the problem trying 3DR posted specs of using 880kv with 11x4.7 props and a 4s this time I might have to switch the props to 10x4.7 when i use the 4s battery instead of the 3s.
Hi wessie,
Your failure description looks quite close to the one I had recently, also with no apparent cause for the drop in motor power that caused the crash : http://diydrones.com/group/arducopterusergroup/forum/topics/help-ne...
I also excluded : geofence limits, loss of GPS, ESC sof cut out (voltage was still high enough), no motors problems, no broken props. I saw another thread about sun light impact on barometer, even if APM is encased, that could provoke a drop in altitude, but I can't determine if this could be the cause.
Very annoying as theses gremlins could come back anytime. (by the way I flew afterwards the exact same mission with same quadcopter without problem...)
Some random comments after reading this entire thread: First off, low-voltage and thermal cutouts on ESCs will obviously result in a crash on multicopters if they engage and thus are worse than useless. Also did not see mentioned anything about bullet connectors (esc/motor); these can be a source of trouble; reseat them all, maybe use a gel. Also some motors may need a bit of end-play so they don't bind up when they get warm. Loose prop(s)? Also suggest close inspection of all of the wire connectors to the pins on the Rx and APM, at least that will re-seat them (I'm surprised we don't have more trouble with those, or maybe we do and just don't know it). Look for chaffing where wires run over any sharp edges (a source of trad heli crashes).
Hope you find & kill the gremlin!
You mentioned the only damage was one broken propeller. Is it possible the blade broke in flight and that is what caused the crash. I have had blades break on my Hex in flight. Came down hard, but with 5 motors still working it was manageable. Actually got video of one that was in front of my camera. I could also hear the change in the audio. Good luck.
Is it possible the logging frequency is much lower than the ESC frequency? Ie you might miss a spike inbetween two log samples, but the ESC picked it up and did the voltage cutoff?
My plane motor cut out recently and wouldnt restart, even in manual. Luckily I was simply able to glide it home. Back on the ground it worked fine, without looking at the logs I concluded it was the ESC low voltage cut.
It then occurred to me that having this on with Ardupilot is a disaster waiting to happen, as if this happens during Auto the APM wont know anything about it. Im not sure I ever read any warnings to that effect in the wiki, but it might not hurt. I like the idea of a checklist in the ground station too.
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