Geoffrey wrote:
> There is one called (not sure of spelling) michaelson Interferometer
> that uses a laser interference pattern to count the patterns
> and use this to tell the deflection of whatever.
>
> Have you ever seen anything relating to bouyancy or levitation ?
>
> I have the awareness that it might be possible with the aid
> of a PID loop (Proportional/Integral/Derivative) feedback
> like the cruise control in a car used in conjunction with
> a hall effect sensor to fix a mass at a stable point and measure
> the energy used to keep it at the refrence point.
> PID is commonly used in industrial control to fix settings
> like temperature and flow rates.
> Any Ideas Here ?

   Yes, the PID "force feedback" thing has been done. Here's an example:
http://www.keckec.com/seismo/

>
> Regards;
> geoff
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