AW: [sdiy] Phototheremin and ultrasonics....

[Ullrich Peter]

>Ultrasonics are not easy to use for this position sensing
>application, especially in multiple axis.
>
>There is a minimum distance in most apps... generated by the
>amount of time the transducer 'rings' after you transmit a pulse.
>
>You cannot use a fixed frequency because of the potential for destructive
>interference from multiple reflective objects... the Polaroid (and similar)
systems use a pulse >burst of several spaced frequencies so that
>one of them is bound to get through...

The circuit of the polaroid system is online on a robotics page...
I don't have the link but I can send the file if someone needs it.

Another method:

I made a concept for a design competition using gyroscope chips on 
each finger for midi controllers.

Ciao
Peter

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