Advanced autopilot tuning tips: Difference between revisions

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In response to [http://www.mail-archive.com/flightgear-devel@lists.sourceforge.net/msg25856.html this question], see [http://www.mail-archive.com/flightgear-devel@lists.sourceforge.net/msg25859.html] for original response:
In response to [http://www.mail-archive.com/flightgear-devel@lists.sourceforge.net/msg25856.html this question], see [http://www.mail-archive.com/flightgear-devel@lists.sourceforge.net/msg25859.html] for original response:
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iteration the controller sees an error but has no 'trend history'  
iteration the controller sees an error but has no 'trend history'  
to know how effective its correction is, and so may command the max  
to know how effective its correction is, and so may command the max  
correction. As the aircraft responds to the initial correction  
correction. As the aircraft responds to the initial correction  
though, the controller gets feedback upon which it then gauges the  
though, the controller gets feedback upon which it then gauges the  
correction for the next iteration.
correction for the next iteration.
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airspeeds you might need the Pitch-hold controller to be pretty  
airspeeds you might need the Pitch-hold controller to be pretty  
brutal and almost driving into oscillation but at high speeds you  
brutal and almost driving into oscillation but at high speeds you  
need it to be much more delicate. However, judicious use of  
need it to be much more delicate. However, judicious use of  
filters and variable gains can usually get you around most  
filters and variable gains can usually get you around most  
problems.
problems.
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initially worked, I think it may have become broken at some point  
initially worked, I think it may have become broken at some point  
and the rate at which the controllers and filters operate depends  
and the rate at which the controllers and filters operate depends  
more upon the frame rate than anything else. Because the rate at  
more upon the frame rate than anything else. Because the rate at  
which the controllers work is critical, depending upon the gains  
which the controllers work is critical, depending upon the gains  
used, a controller that might be stable on one system might become  
used, a controller that might be stable on one system might become  
unstable on a slower, or even sometimes a faster system (I've seen  
unstable on a slower, or even sometimes a faster system (I've seen  
this sort of problems happen both ways).
this sort of problems happen both ways).
== Related content ==
* [[Autopilot PID controller tuning resources]]
* [[Autopilot configuration reference]]
[[Category:Aircraft enhancement]]

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