Flip crash at launch

[rput]

Hi all,

After an initial good start with my 2nd AQ board (1st one was fried by me... ) I just encountered some strange behaviour.

I was going to show the stability of the quadcopter with AQ at a friend who lives about 50 km away. The quad was armed and then put in position hold. Then I slowly increased throttle (as I had done before with the same quad) and instead of taking of, it made a nice sideways flip as can be seen on the video link (slow motion):



I looked at the logfile, but am not sure what is going wrong. I do notice some strange spikes in the motor signals:

Here is the full logfile:

055-AQ.Log

(1.07 MiB) Downloaded 524 times

I also notice some sawtooth on the UK_POS parameters:

Any insight would be much appreciated.

[Kisssys]

Looks like your XY gyro is bad. Static they should be about 1.33 volts.

[leopold1]

A question.
Did you plug in the battery of the quad and then moved it to the launch position? It could be that the initial calibration was bad. I had two crashes for this reason. I now do a short test preflight and if bad you can see some strange behaviour and land quickly. Replugging the batt resolves it. And letting the quad calibrate undisturbed.

[rput]

Thanks for the replies. I think I indeed had it plugged in before moving it to the launch position. That could explain it.
Is there any problem with launching in Position Hold mode?

[leopold1]

I would do it. Altitude can be jumpy and you need a gps fix.

[rput]

@Steve, Where can I check the Z-gyro voltage? I have reset the firmware, mixing table, and other parameters and it is flying again but RTH is now not working good yet. I doubt this is linked, but could it be? Either way I would like to ensure my voltages are ok.

@Leopold, did you mean wouldn't?

[Kisssys]

LOG_VOLTAGE 0 1 and 2 are gyro x y z. This is a plot of raw data from the gyro sensor's from the 055-AQ.LOG you posted.
I would be very cautious flying until to find out what's going on.

[Kisssys]

Hi rput,

The X and Y gyro is one IC and the Z is a different one. It looked like your X Y was not working at the time. On the gyro sensor's the voltage when the copter is sitting still should all be about 1.33 volts. I would guess it's a soldering joint on the voltage doubler circuit which sometimes with a little flux and solder you can resolder them. If it's a new board you might first discuss this with whom you bought it from before you go messing with it.

You might try a little heat and a little cold to see if it comes and goes.

Cheers
Steve

[rput]

that is very illuminating, thanks for the detailed explanation Steve. I will contact the seller to see what he suggests.

Cheers,
Richard