Re: [Emc-developers] pid with derivative inputs

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

Jeff Epler wrote:
>
> what you don't see in the picture is the difference in the noise.
> Without the improved velocity estimate, there's a sickly hum or honk
> coming from some part of the machine resonating
Yes, the Y axis of my minimill has a Japan Servo disc motor, and it 
produces a
very annoying sound almost like it has sand in the bearings.  I know, 
from tuning,
that this is the quantization noise coming through the D term.  If I get 
to Wichita,
I can demo this noise.  I may not bring the minimill, but I definitely 
will bring one
of those motors, I can clamp it to a table for a sounding board.  This 
noise is
exactly the symptom of what I want to get rid of.

Jon