Hello Everyone - I'm hesitant to start a new discussion but I can't seem to find any information to solve the problem I'm having. I'm very desperate to figure this out! I have a Tarot 690 hex with a genuine pixhawk (v3.3.2). I have flown it about 30 times without any problems whatsoever. However, I've had 2 flights now where it immediately spins out of control on take off. The first time this happened back in March. After many (12+) hours or research I settled on it being caused by EMI from a bad battery that I had been using for the 1st time (now I'm doubting this). So I proceed to fly many many more flights and did not have any problem. Then last week seemingly out of nowhere it happened again.
I'm thinking it might have something to do with the compass system. I am using a 3DR GPS/Compass external mounted high up on a mast. I have been getting pre-arm messages about "inconsistent compasses" from time to time. But I have been able to clear them with compass recalibration. This happened right before last weeks crash.
I don't know if a compass miscalibration could cause this type of behavior. It's a really fast yaw spin in a tight circle. I have looked at the logs and I can't figure out if the compasses are abnormal.
Is there someone that could possibly look at these logs and help me determine the problem? Even if someone could just look at the compass data I'd so much appreciate it! Thank you!!!!
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If anyone could please help me out here I would be so grateful. I'm so confused as to why this keeps happening. I've spent many hours reading the forums and inspecting the hex. I'm about to replace all the ESC's... I don't know what else to do. I've attached the most recent crash log.
16-05-23_18-43-12SpinCrash.bin
From the logs motors 6,1, and 3 are spinning faster than 5,2, and 4. This should generate a counter clockwise rotation.
The logs show that your rotation was clockwise so it looks like a hardware issue.
Compass will not cause spinning.
Here is a test flight that behaved normally. Is it normal for the 1, 3, 6 (green in graph) motors to be spinning consistantly faster than the 2, 4, 5 (blue in graph)? I see this happening even when there is no yaw rotation (yaw is red). There were no issues with this flight.
NormalFlight.png
Thanks a ton for looking at this Michael. I believe the 2 logs show the drone spinning in opposite directions. Is that correct? The 16-03-07 log is counter-clockwise and the 16-05-07 is clockwise?
If there were a mechanical problem I would imagine the direction of spin would be consistent. Or maybe not?
Right the first log shows a slow rotation with motors 3 and 4 being neutral. 2 and 5 are high and 6 and 1 low. The usual cause is that one of the motors is leaning in that direction.
Ugh - I'm still having the same intermittent problem. I will have 1-2 successful flights and then it happens again! Here are 2 more logs. The first flight went fine at the beginning and then it started spinning out of control towards the end of the flight. The second log is from today - it just started spinning at take off (like most of the other crash flights). There was a perfect flight in between these 2 crash logs. I really really wish I could figure what is causing this! I've triple checked every mechanical connection. Maybe a bad ESC? I'm at a loss. Please help if you can!
It wasn't letting me attach files earlier. Here are the 2 logs....
16-05-17_17-19-00Crash.bin
16-05-23_18-43-12SpinCrash.bin
You're amazing! It turns out motor number 4 had come loose. I was so fixated on it being a compass issue that I missed this. I'm amazed you saw this from the log!
It's still a mystery to me what happened in the second log. This was from 2 months ago (and many flights in between). I can't imagine this motor could have been the problem then too. I see what you mean about the motors not matching the direction of rotation. So maybe another hardware issue. I had linked the issue to a new battery. To test the theory I even flew with the same battery a second time and had more strange behavior and another crash. Have you ever encountered something like this?
Thanks so much!!