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M4 strange behaviour

PostPosted: Sun Mar 27, 2016 11:25 am
by whizz101
Hello,

I recently damaged my AQ6 and replaced it with an m4. All went well in the build and everything seemed good, i loaded up the same pids as i had been using with the AQ6.
I had completed three flights with no major problems. I had had some issues with my Hacc & Vacc jumping around a bit , but i put this down to flying in a a deep valley.

The problems occurred on the second half of my third flight, It started to sort have a few glitches on the yaw axis, so i decided to land. As i was positioning for touch down, just a few centimetres from the ground, she suddenly tilted forward and tried to fly off! At that point i immediately shut down power. The result was a couple of broken props and a hard landing.

I am totally at a loss to why she tilted forward. I was in manual mode. It was as if i was in position hold with low Hacc and Vacc and she was trying to reposition.

I have looked at the logs and can see that my vibration on the z axis has increased since the first flight i did the day before, But i don;t think this would have the effect that i suffered.

I would like to upload the log, but it is close to 30KB and there is a limit of 5KB here. How is everyone else doing it.?

Any help working out why this happened would be very much appreciated...

Re: M4 strange behaviour

PostPosted: Sun Mar 27, 2016 11:44 am
by aBUGSworstnightmare
Use dropbox for the logs.

Let us have more details on your craft.

Re: M4 strange behaviour

PostPosted: Sun Mar 27, 2016 12:05 pm
by whizz101
I am a dropbox newby.....

It seems i need your email address to share?

Re: M4 strange behaviour

PostPosted: Sun Mar 27, 2016 12:32 pm
by whizz101
ok, think i worked out dropbox!

This link should give you the three logs of the three flights.

https://www.dropbox.com/sh/v21zkqa9zrrb ... mJ4sa?dl=0

Re: M4 strange behaviour

PostPosted: Sun Mar 27, 2016 1:07 pm
by whizz101
my set up!

20160327_135931.jpg

Re: M4 strange behaviour

PostPosted: Sun Mar 27, 2016 1:51 pm
by brat002
I also had similar problem, that was solved after redo mag calibration.

Re: M4 strange behaviour

PostPosted: Sun Mar 27, 2016 2:02 pm
by whizz101
brat002 wrote:I also had similar problem, that was solved after redo mag calibration.

Interesting, I had been doing the mag calibration just before that flight....

Is there any way to look at the logs to see a problem with the mags?

And why would mag calibration have the effect of tilting the copter forward? i can understand it messing with yaw,but not forward attitude?

I was just about to fly again for first time... i will redo the mag calibration.

Concerning the mag calibration, should i have all my servo's and fpv transmitters on whilst doing the mag calibration?

Thanks for the info....fingers crossed for next flight!

Re: M4 strange behaviour

PostPosted: Mon Mar 28, 2016 8:58 am
by chschmid
When you boot the M4 and connect to QGC, does the primary flight display show the right direction?

Cheers
Christof

Re: M4 strange behaviour

PostPosted: Mon Mar 28, 2016 10:26 am
by whizz101
Hello again...

The mag is about 10 degrees off. i have done several calibrations on the mags, but always seems off!

I'm going to do it in a new place today!

Re: M4 strange behaviour

PostPosted: Mon Mar 28, 2016 10:47 am
by whizz101
Hello again.

Is there a way to see how hard the sensor filters are working from looking at the logs?