Re: [Emc-developers] pid with derivative inputs

[Jon E. <el...@pi...>]

Andy Pugh wrote:
> This sounds like a problem related to the one I am having with my
> resolver converter, and one possible solution would be a tracking
> filter (
There was a chip made by ST, the L290, a quadrature to voltage converter.
It decoded the quadrature into + and - moves, and then had two freq-voltage
converters, one for each direction.  It then took the difference of the two
outputs.  Dithering would cause that chip to output a near-zero result.

I think I could come up with a similar scheme for the velocity estimate.
The current scheme uses a velocity that is derived from time between pulses,
and is therefore signless.  But, I think I can use the position delta to 
assign a
count-by-count sign to the velocity from the timestamps.  I'll have to 
work this
out on paper first.

Jon