On Tuesday 18 December 2007 22:52, Tiago Gusmão wrote: > LeeE wrote: > > Hi all, > > > > I've noticed recently that after re-loading an autopilot the > > filters that are being used seem to be getting a bit > > 'confused'. I spotted it when I was comparing the unfiltered > > input with the filtered output and saw that the input was > > stable to 2 decimal places but the filtered output seemed to be > > oscillating very quickly up to the first decimal place. > > > > I don't know if this happens with all filter types - all the > > ones I've been using are noise-spike types. > > > > LeeE > > Are you sure it's oscillating instead of just catching up with > the current input? anyway, you can try to enable debug on that > filter and show us some values. > > In the meantime i've had my own problem with the AP (now solved, > don't use alpha=0 or you will get a NaN that will bring FG to a > halt if tied to the controls) > but i found some things that don't make much sense to me > > xmlauto.cxx, line 798, FGXMLAutopilot::reinit: > > -why is build() called there? it's already called inside init() > > -maybe my C++ is a little forgotten, but don't we need to delete > the objects contained in components() ? > > Cheers, > Tiago
Hi Tiago, I'm not absolutely sure it's oscillating - it's changing too fast to actually see the numbers to be sure - but the visual pattern - that is, the apparent 'shape' that you can see suggests it is rapidly switching between two values, which change more slowly, over time, as the input changes. Like I said, I compared the un-filtered input with the filtered output and while the input could be stable to 2 decimal places the filtered output could be changing at the first decimal place i.e. the output was varying more than the input by a factor of up to 100, so it's not a case of the filter trying to catch up. The effect is that it is oscillating because it's vastly overshooting it's target in both directions. LeeE ------------------------------------------------------------------------- SF.Net email is sponsored by: Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
