[simpits-tech] May the Force Feedback be with you...

[Matt Bailey]

On Saturday 08 February 2003 17:03, you wrote:
> Hi All,
> I woke up this morning and was thinking of some comments for this problem
> of trim and centering the stick. Matt has said it well. My comment for trim
> was going to be the same. As for the closed cylinder I'm not so sure. If
> the cylinder is closed the movement of the shaft will increase the pressure
> to a point were you can't move the shaft.

	Hmmmm, true. But you don't necessarily have to have full control deflection 
occur at full cylinder compression. You would want to leave a few percent of 
the cylinder available at full stick deflection, for the compressed air to 
occupy. This way you could get full stick deflection.

> The cylinder will need to be big
> so the amount of movement won't increase the pressure much.

	You could just make the compressor component of the cylinder (the part 
connected to the stick...sorry, I don't know the correct name for this 
device, plunger?) smaller to decrease the rate at which pressure builds. You 
DO want pressure to build fairly rapidly. Getting the distances, travel, etc 
right would require experimentation. I picked this method because by its 
nature it seems to fundamentally match what happens in the real world. A very 
slightly sloppy center position, with naturally increasing pressure as the 
control is moved further from center.

> If the cylinder
> is attached to a big chamber(and maybe this is what you are thinking Matt)
> then the movement of the cylinder won't be noticed.

	I don't quite follow this part. By cylinder, are you referring to what I was 
trying to say earlier by "plunger"? The part that goes inside the chamber.

> This system will also
> need two cylinders per axis.

	Yep.

> My idea may work, use an innertube around a
> circular disk (attached to the stick) inside a retaining ring. The pressure
> would be controlled the same way but when you move the stick the disk would
> press on the innertube and you would feel the pressure. The air would
> simply move to the otherside of the tube and the pressure would remain the
> same. The stick would self center because the tube would go back the the
> orginal shape. This would be the same pressure in all directions.Trim would
> be just moving the tube assembly to a different center. Any thoughts or
> comments?

	Interesting. I don't really think just moving air around is sufficient, you 
want some compression going on. But, you'd be compressing the air by reducing 
the space inside the tube. The logistics of the system would be much simpler 
than my idea.

	-Matt Bailey