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[DPRG] Odd numbered segments

Subject: [DPRG] Odd numbered segments
From: Kipton Moravec kip at kdream.com
Date: Wed Aug 29 22:18:18 CDT 2001

Most honored and respected robot master:

You have to say an odd number of white bars if you are reflective or an odd
number of holes if you are transmissive.

So if you are counting white bars or holes, you are talking 3,5, 7, 9, 11,
13, etc..

If on the other hand you are counting white and black as two divisions as
opposed to one cycle then the pattern is 6, 10, 14, 18, 22, 26, etc...

The terminology is the problem.

Kip

----- Original Message -----
>From: "David P. Anderson" <dpa at io.isem.smu.edu>
To: <dprglist at dprg.org>
Sent: Wednesday, August 29, 2001 9:01 PM
Subject: [DPRG] Odd numbered segments


> Hi
>
> The most excellent Dan Miner wrote:
>
> > PS - I thought the quadrature encoder solution of placing the
> > sensors 180 degrees apart and using any odd number of bars (except
> > 1) was very clever.  So simple yet it eluded lots of us.  I wish I
> > had thought of it...
>
> I don't follow.  Don't you have to have an equal number of white
> and black segments?
>
>
>                 |
>                 |
>                [1]
>                 |
>                 |
>                / \
>               /   \
>              / [2] \
>             /       \
>            /         \
>
> If you have an odd number of segments, like 3, then the 180 spacing of
> the sensors solves the condition that one sensor be on the line and one
> be in the center.  That's true.
>
> But the segments consist of rising and falling edges as the sensor moves
> from black to white to black segments.  For 3 segments that would be BWB
> or WBW, in either case segment 1 and 3 are the same color, no edge between
> them.  So its just a 2 segment encoder with one segment twice as long as
> the other.
>
>                 |
>                 |
>        White    |   White
>                 |
>                 |
>                / \
>               /   \
>              /     \
>             / BLACK \
>            /         \
>
> Same for any odd number of segments.  Yes?
>
> regards,
> dpa
>
>
>
>
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