Re: [Flightgear-devel] [off list] patch for control lockingbyautopilot

[woodyst <wo...@gm...>]

2007/7/3, Roy Vegard Ovesen <roy...@ha...>:
> On Thursday 28 June 2007 19:50, woodyst wrote:
> > With my yoke stopped, with js_demo i see a lot of lines as:
> > | 0000 -0.0 +0.1 +1.0 -1.0 -1.0 +0.0 +0.0   .  |
> >
> > all of them without changes.
>
> Since it only shows one decimal digit, a change of 0.002 would not be shown in
> js_demo.

Yes, it was the problem. I changed js_demo.cxx so it puts 3 decimals
and then I can see an ocasional movement of 0,010 some times.

I apologize if I've confused someone with my previous posts.

>
> >
> > So autopilot may change axis values (because my yoke is not noisy) and
> > this difference (position 0 of yoke and autopilot setting) may be greater
> > than a.tolerance, so it vibrates (I think, correct me if it is not
> > correct).
>
> I think you have misunderstood how input.cxx works. It does not look at the
> difference between the joystick position and the autopilot stick position. It
> looks at the joystick position from the previous sample and if the joystick
> hasn't moved more than tolerance, then its new position is not applied.
>
> You could hold the joystick in the full right position, far away from the
> position that the autopilot wants the stick to be in. But if you can hold it
> still there then input.cxx will not update the position and the joystick will
> not fight with the autopilot.

It is correct.

>
> > > > No, it is not noisy. I have tested it with utils and found that my yoke
> > > > is very quiet. I think my previous afirmation may be correct.
> > >
> > > Very quiet might not be quiet enough. If the noise is more than the
> > > tolerance value hardcoded into input.cxx (0.002) then you will see what
> > > you are seeing.
> >
> > When I do not touch my yoke it does not pass any event. So there may be
> > another problem with it. Please probe it by your own keeping your
> > joystick stopped
> > (test it with js_demo or something similar). You will see what is my
> > problem.
>
> I have actually seen the problem. My joystick (Thrustmaster(r) Top GunTM Fox 2
> ProTM USB) is actually quiet enough that when it sits on my table untouched
> in the center position, it does not fight with the autopilot. If I bump the
> table, jump up and down on the floor, listen to loud crappy music, etc. then
> it will vibrate, and it will fight with the autopilot.
>
> _I_ am still convinced that your joystick is more noisy than the tolerance
> limit in input.cxx. I have a few suggestions you could try:
>
> - If the joystick driver has a dead zone option try that.

I have put it in the fgfs file that describes my yoke. I have
calculated the ideal dead zone for eliminating noise. It is about 0.01
(the deviation I saw in previous tests. I have used 0.01 because it is
the max deviation from center I have observed with yoke centered.

> - Try setting the tolerance limit in input.cxx to a higher value.

This is a problem, because then it only reacts to my movements every
+-tolerance increment, so I lose sensitivity (and this is a very good
yoke).

> - Remove the noise from your joystick: clean or replace the pots.

The yoke is almost new. I think noise may be caused by the internal
design of the yoke plus the vibration of the table, that it is very
weak. I think the dead zone in the xml is the better solution for me,
because I maintain the sensitivity of the device.

Thank you very much for your patience. Sorry for the large discussion,
but I was desperate and autopilot was unusable in my machine.

Nevertheless I think this thread has contributed with some very
interesting new ideas for the AP that I would like to improve.

If we get any common point of view I would be grateful and I would
help in implementing some changes.

Best Regards.

Woodyst.

>
>
> --
> Roy Vegard Ovesen
>
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-- 
Woodyst.