Quadcopter crash - please help! - ArduCopter User Group

Good evening all

I was recently flying my quad and about 6 mins into the flight it suddenly flipped and plummeted to the ground. I have had pretty stable flights in most flight modes up to that point and all of the hardware is luckily still working after the crash so the root cause is baffling me. Im busy rebuilding the quad now and i'd really like to understand the problem before i finish.

Im still a noob at analysing the logs but at the end of the flight the pitchIN and rollIN flatlines and the barometer starts to pick up the decent. The sonar is pretty noisy when it is out of range - not sure if this is a contributing factor??

I have also tried to attach the T and R logs but i keep getting errors so if you would like to see them i will send them with another method.

If anyone can shed some light on this i would really appreciate it!

Thanks

2013-02-24 21-17 7.log

2013-02-24 21-17 7.kmz

2013-02-24 21-17 7.log.gpx

Alberto,

Ok, so you're running 2.8.1 which is a very well tested version of the code and the issue happened while the copter was in stabilize mode so it's extremely unlikely that it's a software issue, it's more likely a power or mechanical failure.

Looking at the barometer altitude you can see the altitude ends suddenly while the copter is still in the air. This is most often caused by a brown-out.

Just before the end of the logs, as you say, the the Roll-In and Pitch-In values drop to zero which means that either the tx/rx lost contact with each other and the radio's failsafe kicked-in or ppm encoder browned out (the ppm encoder browns out at 3.0v while the 2560 browns out at 2.7v - in 2.9.1 we can log the failure of the ppmencoder but in 2.8.1 we don't so it's impossible to be sure which it is).

Around the same time the roll/pitch values start to diverge from the roll-in/pitch-in. This could be caused by the low-voltage protection on one of the ESCs kicking in and reducing power to one or more of your motors (you might want to check your ESCs and ensure the low-voltage protection is turned off).

By the way, you should increase your Rate Roll/Pitch I term to 0.1. The defaults were too low in 2.8.1 and we can see your actual pitch is off from the desired pitch (Pitch-In) by 10degrees at time and the error is consistent...a clear sign that I is too low.

Hope this helps.

Replies

Pedro H July 15, 2014 at 2:00pm

Hey Albertino, on your TBS Discovery; did you get the Core power with it?
After my crash on my old quad; i'm ordering the TBS Disco also with Core.

I'm hoping the Disco Core will eliminate the brownout issue.
Developer

Randy March 4, 2013 at 8:35pm

Alberto,

    Ok, so you're running 2.8.1 which is a very well tested version of the code and the issue happened while the copter was in stabilize mode so it's extremely unlikely that it's a software issue, it's more likely a power or mechanical failure.

    Looking at the barometer altitude you can see the altitude ends suddenly while the copter is still in the air. This is most often caused by a brown-out.

    Just before the end of the logs, as you say, the the Roll-In and Pitch-In values drop to zero which means that either the tx/rx lost contact with each other and the radio's failsafe kicked-in or ppm encoder browned out (the ppm encoder browns out at 3.0v while the 2560 browns out at 2.7v - in 2.9.1 we can log the failure of the ppmencoder but in 2.8.1 we don't so it's impossible to be sure which it is).

     Around the same time the roll/pitch values start to diverge from the roll-in/pitch-in. This could be caused by the low-voltage protection on one of the ESCs kicking in and reducing power to one or more of your motors (you might want to check your ESCs and ensure the low-voltage protection is turned off).

By the way, you should increase your Rate Roll/Pitch I term to 0.1. The defaults were too low in 2.8.1 and we can see your actual pitch is off from the desired pitch (Pitch-In) by 10degrees at time and the error is consistent...a clear sign that I is too low.

Hope this helps.
- François LABAT > Randy May 1, 2014 at 12:34pm
  
  Hi, thanks for you help, this site is very helpfull. I upload the new version 3.1.3 on my APM 2.5 with a TBS Quad Frame. All was great when suddenly at full throlle, motors spin low. I land and it flip on his back! I tried to disarm but impossible to do it ! I managed to stop it after a few seconds!
  
  I'm joining log! Could you help me?
  
  Thanks a lot!
  
  2014-05-01 16-10-34.log.gpx
  
  2014-05-01 16-10-34.log
  
  2014-05-01 16-10-34.kmz

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