On Wed, Nov 5, 2008 at 7:30 PM, Csaba Halász wrote:
> On Wed, Nov 5, 2008 at 3:20 PM, Curtis Olson <wrote:
> > What is the proper mechanism for calling nasal initialization code in an
> > aircraft specific nasal file.
> >
> > I see that core nasal code sets a listener on
> > /sim/signals/nasal-dir-initialized however, I don't really care when the
> > nasal-dir is initialized for aircraft specific code since it doesn't live
> in
> > the main nasal directory. Would it be nitpicky of me to ask what it
> means
> > to initialize a directory? Is there a corresponding unix system call for
> > instance? :-)
>
> Slight misnomer, not the directory is initialized of course. Rather,
> the signal means all the modules in the nasal dir are loaded and ready
> to use.
>
> > So is there a "proper" way to do this. I understand the old "set timer"
> > mechanism is discouraged.
>
> Preferably you should wait for a signal that whatever features you
> want to use are ready. If you *use* any modules from the common nasal
> directory (including props.nas!) you should wait for the
> nasal-dir-initialized. If you depend on fdm properties, you should
> wait for fdm-initialized, and so on.
>
> Disclaimer: I am not *the* expert on this, but since nobody answered
> yet, I thought I'd give you my understanding of the situation :)
Thanks, I ended up waiting for the fdm to initialize and that seems to work
just fine. I am prototyping some ideas for velocity hold via elevator for
my UAV project. In simulation it seems to work *really* well to think about
controlling the change in velocity with the elevator. Your actually
velocity responds very slowly to elevator change and it's very difficult to
build a stable single stage controller that takes velocity error as the
input and drives the elevator directly. But if you use velocty error to
command a target acceleration, and then try to achieve that acceleration by
manipulating the elevator, I quickly achieved what I would characterize as
spectacular results. Now the question will be if I can mimic those same
results with a noisy pitot tube sensor, turbulent air, and all kinds of
other inacuracies and biases in the system.
I really need to get my web site update with some pictures of our new
airframe because it is super cool (a flying wing with blended body
fuselage.) And I have a neat movie of it coming off the launcher (I put
myself within inches of death trying to cock that thing by myself on
Monday.)
Curt.
--
Curtis Olson: http://baron.flightgear.org/~curt/
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