RE: [CAD_CAM_EDM_DRO] re: using optical mouse for DRO / servo feedback

just to clear up a misunderstanding....

The counts per inch don't vary willy nilly between 400 and 800 (otherwise I
wouldn't have suggested it as an encoder), but rather are software
selectable at 400 or 800 CPI 400 giving a higher limit on top speed of
movement than 800. The chip uses a tiny low-res camera to take successive
microscopic photos of the surface (1500 a second), and a motion detect
algorythm to compare the changing position of features on the surface,
thereby calculating the movement in x and y.

check out the agilent website.

Nig


-----Original Message-----
From: Jon Elson [mailto:elson@...]
Sent: Thursday, March 13, 2003 5:55 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: Re: [CAD_CAM_EDM_DRO] re: using optical mouse for DRO / servo
feedback




Nigel Bailey wrote:

>Just come through from Farnell electronics (a distributor) on the new
>products is an optical mouse sensor for use on "a surface", it just reads
>the surface, be it a mouse pad, a bit of desk-top, an envelope (or possibly
>a dusty rail), and uses an on-chip camera and some signal processing to

give

>400-800 counts per inch x and y. Quadrature or serial outputs, etc. maximum
>speed of motion it says are 12 inches per second.
>anyway manufacturer is AGILENT, and part number is
>ADNS-2051, looks promising
>
>

400 - 800 counts per inch? How can you make a measurement system where
there is
a 50 - 100% variation in gain? This will work for moving a cursor on a
screen, but
won't do for a motion control system. If it was a consistant scale, you
could at
least use it for a DRO. But, for a servo feedback system, you also need
a fairly
fast update rate, and I suspect this may not give that.

Jon


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