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Rudder servo offset in FBWA

Posted by Martin on August 30, 2013 at 6:00am

I have an APM 2.5 running Arduplane 2.74b. I have the autopilot mounted upside down. I have already changed the relevant setting and re-leveled the plane.

So, my problem is that when I switch to FBWA the rudder centre position offsets to the left. The offset is probably about 40% of the full servo range. That's a lot, almost at the end of the range.

The plane is a rudder-elevator only model. I have set the rudder to aileron mix to 1. The offset doesn't happen in stabilize mode. The rudder stays centered as in manual mode.

I was planning on tuning the pid controllers, but did not dare to fly the plane. Any recommendations?

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Replies

  • Søren Kuula August 31, 2013 at 3:23am

    Hi,

    The plane is a rudder-elevator only model. I have set the rudder to aileron mix to 1

    You must mean the aileron to rudder mix and not opposite?

    Well ... try to isolate the problem. If you return the autopilot to "normal right side up" orientation, does it work as expected?

    You have checked the INS (looking at the horizon in the mission planner) to see if you got the upside down configuration right?

    Not relevant for this problem but be careful: Also check the compass heading.

    Regards

    Soren

  • Martin August 30, 2013 at 7:13am

    If I set KFF_RDDRMIX to 0, then naturally there's no offset in FBWA, but when I set it to anything other than 0 then there's a fixed offset.

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