[Paparazzi-devel] Tuning the vertical loop for rotorcraft fw

[Christoph Niemann]

Hi everybody and a happy new year!

Currently I'm doing my first steps tuning a rotrcraft. The ATT loop
seems to work well but I'm experiencing problems in tuning the
vertical loop. To do so I took my airframe into a hall with a ceiling
allowing to fly about six meters high without being disturbed by wind
and also not to fly in the ground effect.
So far I'm trying to do this in the Attitude Z Hold Mode. In my
opinion I should activate it and then give full throttle to allow the
controller to control the height. To have compareable results I
allways the set the altitide setpoint to a determined value.
What happens when I engange it? It gives to much thrust and fly up to
the ceiling until it reduce the thrust and get It back. You can the
the pattern in the enlosed plot.
I have no clue what to do. I played around with the contoller values
and tried for instance puttin everything to "0". By increasing the
pgain again a valiue of lets say 80 is enough to reproduce the
behavior again. I also tried to set the nominal throttle by hand, I
think with very few success.
Now I have no idea. Which values should I have a look at? What could
be the problem? Did I missunderstand something?
What I've got to say its a pretty old Paparazzi
(v4.0_stable-13-gcca26bb-dirty) but currently I can't update it, since
the Hardware is pretty beta, but the hw shouldn't be the problem,
since the z value seems ok to me.

Kind regards and thank you for your help

Christoph

vloop.png
Description: PNG image