Stabilize & FBW invert the plane!

Hi folks,

 

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!

spag

inverted z axis on acc.jpg

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Replies

  • Thanks for the advice guys!

    Inverted mode is set to 0 in the params list.

    I believe my roll was inverted in the radio calibration menu.  I've re-configured everything again.  I did verify proper aileron and elevator direction while on the ground in stab mode, but the prop spun up once I entered the mode, so I may have been distracted by that... is it supposed to start spinning in FBW A and Stabilize modes?

    I've re-leveled, re-calibrated, and re-verified the whole thing again, here.  Rolling the plane farther increases the deflection of the ailerons, just as one would expect... Yet az on the tuning graph shows a solid -1000, just as it did during the flight.  When I invert the plane now, that value climbs up to +1000, just as it did during the flight.

    I'll have to get it in the air to try again, of course, but I don't have much confidence that I've corrected the issue.

    Can any of you who have successful use of stabilize confirm that when level and calibrated your az value is also -1000?  That would settle it, certainly.

    Below is a link to the video of the flight.  The first mode switch was stabilize, then FBW A, then FBW B.  I've also attached the TLOG.  For the actual flight, scroll all the way to 79%.  I was fussing around with everything else prior, forgetting how fast this system can acquire gps.

    http://youtu.be/HAkenhGzHVs

    spag

    2012-07-11 20-46-24 - Copy.tlog

  • Check the wiki under "inverted".  Maybe you have the inverted parameter set.

  • Hi spagoziak,

    Do cpontroll surfaces move the direction they should?
    Just hold it in your hand in stab mode.

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