Another Divergence Problem AQ FW R340....

[Jdmagoo]

I have a divergence problem...

Are my motors/props underpowered??

I have a Hexa X with an AUW of 3kg with TM MN3110-17 motors and TM 11x3.7 props.

Looking at the log file I noticed all motors were clipping during the divergence before the Hexa ultimately crashed.

During hover the LOG_MOT_PITCH and LOG_MOT_ROLL are showing around +- 800. The TILT RATE D is default under FW R340.

Should I reduce TILT RATE D until the value gets below +-500? Will this fix the divergence? Or should I put bigger props on?

The Mixer table is the default table for a Hexa X in GCS 1.3

A real bugger as two props are broken and the VectorDD gimbal is bent (bad) and i don't know that i can repair it. Before the divergence i was blown away by the stability of the platform and how accurate the PH and AH are. With that type of performance i don't know that i could justify the DIMU upgrade. But now the divergence thing happened i might have to rethink this.

Log:
https://www.dropbox.com/s/p50a470vf0shn ... QL.LOG.zip

Video:

http://youtu.be/w08c9TbXQhs

Towards the end of the video just before the hexa hits the ground you can see the Gimbal hit its limits and bounce back. The VectorDD did a good job at handling the divergence, but its too bad it occurred in the first place.

Looking forward to your help

Many Thanks

James

[Cookiemonsta]

I also have these motors with 11 inch graupner eprops and I don't think it's underpowered.
Shouldn't log_mot_pitch and roll be around 300 max?

[Jdmagoo]

[Jdmagoo]

[LPR]

James

When I started flying my octo I had a lot of divergence problem. My motors allowed the octo to hover at around 40% throttle but my props were not balanced and the aluminum heli tail boom arms were too flexible and caused more vibration. If I lowered the tilt rate D the divergence would be reduced. To test for divergence I found while the octo was in pos/alt hold a quick jab of pitch or roll would cause the octo over shoot and then go back and forth a couple of times till it would stop moving and hover.

I had the motor mix at 50 instead of 100 and that was the major cause of the problem. After I reduced the vibration I was able to use 100 in the motor mix and go back to default rate D without have any divergence.

Angle's quad had 15 props and motors that did not have enough power to react quick enough to keep away from the divergence.

Divergence looks to be caused by a multi not being able to change tilt fast enough to have the multi stop were it is trying to stop. I found that reducing rate D helps, more power to the motors help, smaller props helps, a stiff frame helps and of course low vibration helps.

Larry

[Jdmagoo]

[Jdmagoo]

Would the mikrokopter mixing table be more appropriate? Where you read 64 replace this with the equivalent of 100 for AQ

I don't understand why the default mixing table for hexa x has motors with +- 50? Surely you want all motors to be able to output at 100% when the FC requires? Doesn't the FC govern how much output is required for each motor at any given situation, therefore if some motors require 100% then there shouldn't be a software lock restricting this? If I'm right then the default mixing table needs to be changed to something similar to the mikrokopter table as attached and the wiki updated.

I understand that some people reduce the output of the mixing table to make PID tuning easier, but this shouldn't be the default. Reducing vibrations, correct prop and motor selections for the given frame weight should be pushed more than reducing the mixing table outputs. But again I'm still very new to this and am learning every day so could be very wrong. Am looking forward to feedback to all of this.

[Cookiemonsta]

[Jdmagoo]

[Max]