[Paparazzi-devel] Incorrect Proportional Pitch Deflection, Correct Derivative Pitch Deflection

[Chris Wozny]

All,

I've run into a peculiar situation with my PD gains for pitch on my
elevons in AUTO1. I'm using Lisa/M 1.0 on the dev branch. The
deflection I'm receiving to counteract the motion of the aircraft in
pitch is correct (i.e. PITCH_DGAIN is correct.) However, the
proportional gain is the opposite of what it should be doing i.e. when
I'm pitched lower than my set point, the elevons pitch further down
instead of trying to pitch the aircraft back up. The obvious
correction to me would be to flip the sign on the PITCH_PGAIN, but the
range on the numbers is only negative and zero, so I don't know how
that would work. Does anyone know how to flip the effect of the
PITCH_PGAIN? The pitch and roll commands in MANUAL work properly so I
don't think it could be a reversal of the servos that would fix it
(especially since the PITCH_DGAIN works properly.) Finally, the servos
do not hold their commanded position in AUTO1 and overshoot when going
from the commanded pitch/roll back to neutral. I've included the logs
of the flights, the airframe configuration, and even the video of the
(attempted) flight which the logs correspond to. Has anyone seen this
type of behavior from their aircraft?

Video of (Attempted) Flight
http://www.youtube.com/watch?v=i9y_Nh8QQYY

Video of Commanded Input in AUTO1
http://www.youtube.com/watch?v=uDeERiqehjU

Airframe Configuration
http://ece.arizona.edu/~cwozny/mini_vertigo_az_high_aoa.xml

Flight Data/Log
http://ece.arizona.edu/~cwozny/flight_03_filmed.data
http://ece.arizona.edu/~cwozny/flight_03_filmed.log

I hope everyone has a good weekend!

Cheers,
Chris