[DPRG] Re: The quadrature blues, or The Tale of two sensors
Subject: [DPRG] Re: The quadrature blues, or The Tale of two sensors
From: David P. Anderson
dpa at io.isem.smu.edu
Date: Tue Aug 28 14:09:22 CDT 2001
Hi
Kip wrote:
> That is a problem.
<snip>
> After looking at the numbers, if you place the second sensor at 45, 135, 225
> or 315 degrees, then you have the options of any number of divisions that
> fall in the class 4 + 8 * X where x is an integer. For example, 4, 12,
> 20,28, 36, 44, 52, 60, 68, etc. This should be a general enough solution
> for most people.
>
> Since the computer is doing the math there is nothing magic about doing a
> power of two, because you are probably not doing integer math anyway.
For the size of the Hammamatsu sensors and the relatively small diameter
of the encoder disks that we're talking about (1 inch), 32 segments is probably
tops in terms of a practical number of division. Anything greater will
likely need a larger diameter disk. 2,4,8,16,32 is I think a more useful
range of divisions.
I'm thinking after playing with it a bit that I'll go to 16 divisions and
drop my update rate to 30 hz. But this is mere idle speculation at this point...
cheers,
dpa
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