I maidened my APM2 yesterday. It's running the latest code offered by the mission planner--2.34. I've got the skywalker parameters file from april 2012 set on it.
Just as the subject line says, when I switched to either fbw A or stabilize (didn't try fbw b), the plane inverted. I didn't leave it there long enough to confirm that it was trying to level out, but from the footage and the log playback, I'd say that's where it was headed.
To aid in confiming this, I played the log several times with various sensors checked in the tuning window. Seems that the accelerometer Z axis calibrates to -1000 while X and & axes are both 0. I know that the Z would be offset because of gravity, but noting every time I enabled one of those modes during the flight, you can see the Z axis graph climb up to positive values.
So, I suppose the simple question is: how do I invert the Z axis of the accelerometer? Or, why would this be part of a normal setup?
I'm sure it's worth noting that I manually level the plane--I don't have the acc calibrate on boot. I checked to see if I had done that this time, and I believe I did, based on seeing a slightly sharp shift in the values for gyro & acc.
I had done this once by accident in my multiwiicopter. There it was easy enough to add or subtract a - in front of the sensor's raw term. I have a feeling that's not so much the case in such a complicated system?
Your insight is appreciated!