Another Divergence Problem AQ FW R340....

[Jdmagoo]

[Max]

Well maybe not problems per se, but certainly differences. 6.7 is very stable and a lot of people have experience with it, so seems like a good place to start with a new build. But I definitely don't want to discourage you from trying the latest!

-Max

[Jdmagoo]

After reading those links i do now understand why the mixing table is set the way they are. ( to balance power between pitch and roll)

Now this is gonna be hard to explain so please bare with me.

Wouldn't, motors 1 & 2 or 4 &5 (@100%) provide more reactive thrust than 2&4 (@50%) and 3 (@100%) even though they all add up the same?
My trig isn't to good these days but for example. Lets say the pitch motors had to create enough thrust to counter the forward momentum after letting go of the sticks whilst in DVH. The amount of thrust required would be less compare to flying sideways because the two forward motors are equal distance apart on the same angle hence creating the same thrust leverage. If we were flying sideways at the same speed and did the same thing (letting go of the sticks) motor 3 (@100% thrust) would have more leveraging thrust than motors 2 & 4 (@50% thrust each) because these two motors are closer to the COG whilst flying in that direction. So (and please correct my physics if I'm wrong) wouldn't it be better for motors 2 & 4 to have a higher output (higher than 50) to offset this phenomena and balance out the leveraging thrust between Pitch and Roll??

Im basing this theory off the fact that I've only scene this divergence problem (a couple of times now) in the roll axis not the pitch axis.

Or am i way off the mark here?

[Jdmagoo]

[Max]

Any change in leverage based on distance from center is proportionally offset by the distance the motor has to travel to achieve the same amount of total pitch/roll deflection. Eg., roughly speaking, the motor/prop on an arm 2x longer than another will have 2x more torque but will also need to travel 2x further to achieve the same overall tilt angle.

OTOH, since there are 3 motors/arms per side on the roll axis, this makes it heavier than the pitch axis, and may require a bit more power. So increasing the output a bit might help.

There are many other factors which could affect one axis over another, or even just one motor over another. Unless your setup is very unique somehow, I'd tend to start with what has worked for most people (the default hexa mix in QGC). Not saying it's perfect for every situation, but it was mathematically derived, if that makes you feel any better.

Ultimately the "divergence" is the inability of the PID controller to keep up with real-world physics. So either changing the physics or adjusting the controller inputs should fix the problem. It would be cheaper to test this on a rubber-band setup like in some of Menno's tuning videos.

-Max

[Max]

[Jdmagoo]

[teramax]

i am aware that not all here would love to hear my theory but after nearly 3 years of playing with AQ on multible systems i think i can fit this puzzle somehow together.

One thing i could observe every time 100%. The combination of the enormous fast reacting AQ-FC and ESC32 and on the other side motors that could not follow this fast reaction. --woop, rig might fly smooth in normal conditions but fights against divergenze when something unforeseen happens.

I have never had this problems running simple 4in1 BRL-Heli ESC, Turnigy Plush crap or on the other side just powerfull small motors driving small 8" or 9" props.

Think about, this problem does not exist on KK, MWC, DJI, MikroKopter....why?
Maybe cause the have a PID set for every axle or maybe they just react as fast / slow as the motors can handle this reaction.

just my two cents
MäX

[Jdmagoo]

[teramax]

Idea
Maybe we need a button to tell the flightcontroll:" Hey, you have slow fat lacy motors, calm down and handle with them carefully."