Overcompensating (slow) - How to fix?

[hkubota]

A bit background: I got a Naza kit and I like it. In ATTI (ACC) mode flying slowly all is well. Helped a lot to get used to fly around as it's fairly easy to control. However FFF in ATTI mode sucks and it messes what the Naza thinks is "down". So I got myself a Naze32 which is basically MultiWii on a modern platform, to learn proper flying.

Initial tests showed all is working fine: no oscillations. It moves where it should move. Both in ACC and ACRO mode. The main point is ACRO mode, so this is what I want to use. And it should be easier to tune I'd think. I can hover fine. No drift. In ACC mode there usually is a drift in one direction depending on where the battery ends up to be (velcro straps, so it moves a bit every time I change battery).
All the following is for ACRO mode. Software is r204. Quad is small (X move, 20cm between motors, 7x3x3 props, 12A ESC with simonk firmware, 2200mAh 3S battery. PID are default 4.0, 0.030, 23 for roll and pitch. Yaw 8.5, 0.045, 0

The problem:

When I fly forward after a short while (about 3s) the quad compensates and overcompensates, basically stopping the forward flight and going quite a bit backwards. If I decrease throttle, this overcompensation is even stronger and more than once brought me nearly into troubles.

The question:

What parameter is responsible for this behavor?

All docs I found about PID setting are about oscillations, which I don't have.

Harald

[Crashpilot1000]

I is to high

[hkubota]

Thanks for the reply. It was half wrong and half right: I is the parameter (I was not sure of that, so I am very glad you pointed me to the right direction), but it was too low. I went lower and lower and it got gradually worse: the distance until it overcompensated became less. So I move the other way. And lo' and behold: that was it.

For reference: for roll and pitch: P=7, I=0.055, D=23. looptime=2000 microseconds (not sure it matters).
At P=11 I see and hear some oscillations when hovering.

I is very large when I look at https://docs.google.com/spreadsheet/ccc?key=0Aqd4uudAEzq_dDZZaVloOGRpYjB2eFJVTWF6V1F5c1E#gid=0
but then, my quad is smaller than usual.

With those I can flow forward for one soccer field.

Now to tune D...

[hkubota]

A small update here for those who'll read this in the future: I changed in the meantime from GF 7x3.5x3 props to APC Thing Electric 7x5 and with P=5.1, I=0.030, D=23 it flies rock solid and keeps whatever orienation. Very nice flying now.

[vpb]

Maybe the same problem with me, but it's just PID problem, my Y6, ACC PID after tuning is 4.0 0.60 0.20.