Re: Optical mouse for DRO anyone? - not for WIRE!

Hello,

Nice thought; but I'm not sure if it will apply here.

The thickness of a braided shoelace or other braided "hollow"
flat "cordage" doesnt necessarily get thicker when the angle of its
weave changes normal to the direction of its length.

Think Chinese finger puzzle. You can pull it longer or shorter, but
if crushed flat it will still be the same thickness... (The change
to accomodate the length variable occurs in width.)

Hope this helps,

Ballendo

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "R Wink" <rwwink@...> wrote:
>
> If I might comment.. It would seem that moving a soft, pliable
cord through
> any measure device would require a force of some sort against some
> resistance but you might be able to estimate the change in
thickness well
> enough to measure with some sort of accuracy.
>
>
>
> If you have two rollers of known diameters, with nothing between
them, the
> space from center to center would be half the diameters added
together.
> With anything between them, the distance would grow by the
compressed
> material thickness. If you were to use half of the distance
increase in the
> distance calculations, the actual distance would seem to be more
accurate.
>
>
>
> By arranging the mouse such that the "X" axis is the length
measurement
> axis, you could use the "Y" axis as the measurement axis for the
change in
> center distance. If the "Y" axis is polled once every "X" axis
roller rev
> and the calculation adjusted till the next roller rev, it would
compensate
> for the differences in compression along the length.
>
>
>
> R. Wink
>
>
>
> On 4/22/07, mrclicit <HYPERLINK
> "mailto:chris%40clicsys.com"chris@...> wrote:
> >
> > Now I don't feel so bad - you are all (well, almost all) missing
what
> > I said about the medium, and coming up with the same ideas my
> > co-workers offered...now.-..
> >
> > Imagine a shoelace, 100 ft long. Wire and flat strapping or
webbing is
> > child's play in comparison - been there, done all that 25 years
ago.
> > Woven cordage changes dimensionally when even the slightest
mechanical
> > pull, push or squeeze is applied. I have put various types of
lacing
> > (polyester, nylon, natural fiber, etc.) through wire measurement
> > machines with all types of wheels of varying hardness, and they
all
> > performed horribly, losing or gaining as much as 10 inches in ten
> > feet. The company that makes most of these machines even put
together
> > a custom unit for me that they swore would work, and it did no
better.
> >
> > In theory, the optical mouse should be very accurate if used on a
> > surface that has consistent chracteristics. On a Windoze PC, it
would
> > be difficult, since the pointer calls to the API do not seem to
allow
> > the low level of control one would expect - as I recall, the
> > acceleration algorithm is tied to the travel distance in the
available
> > API function. Without being able to compile machine code,
acceleration
> > would be included with distance, hence raw distance throuh a PC
would
> > be an extremely difficult task.
> >
> > Reading the raw mouse output it seems, would be much easier to
do with
> > a PIC and a simple routine to read asynchronous serial. the
velocity
> > of mouse movement establishes the serial clock, and as long as
the
> > chip is clocked fast enough, distance should be a no-brainer. The
> > problem I see with this approach is the storage and handling of
so
> > many variables - even if looped every inch.
> >
> > Time permitting, I'll put something together to try this.
>
>
>
>
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