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Adjusting turn rates? (confused about parameters)

Posted by Foxzilla on May 17, 2015 at 5:38am
Hi all,

After a few years planning, I'm finally in the stage where I can try to fly my plane with the Pixhawk. The first thing I noticed is that the plane (Skywalker 1900mm) turns very slowly (FBWA). After researching a bit about tuning and the different parameters, I first tried to increase the Bank Max and Pitch Max/Min values (LIM_ROLL_CD, LIM_PITCH_MAX, LIM_PITCH_MIN) and this seemed to help the situation. I'm having trouble understanding these parameters though: shouldn't they change the planes max angle? How come changing this value seems to change the maximum servo throws? When tested on the ground with FBWA the servo throws look VERY minimalistic on the default settings so it's no wonder it moved so sluggishly in the air.

Another question about this is the PID tuning - will completing PID tuning (http://plane.ardupilot.com/wiki/flying/tuning/roll-pitch-controller-tuning) also increase servo throw and make the plane do sharper turns? AUTOTUNE is on my to do list, but completing it is challenging when the plane moves so sluggishly (I keep having to switch to manual so that the plane doesn't go too far away).

In short: what are the steps to change how the plane turns and also gains/loses altitude?

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Replies

  • Foxzilla May 17, 2015 at 1:52pm

    Well looks like I just needed to RTFM - inverted rudder servo makes a big difference. There is just so much stuff to remember. Today I had the first successful autopilot mission without changing the default PIDs. This was in almost completely windless environment though, so I think I'm still going to do the autotune at some point.

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