Re: [CAD_CAM_EDM_DRO] Servo question

Tom Murray wrote:

> Here is a question that I have been meaning to post for some time
> now: I read something at the Innovative Automation site (maker of the
> Servo Lite motion control system) a while back that caught my
> attention. The creator of the Servo Lite system wrote:
>
> "For Servo Lite to work properly you need an encoder that will give
> you a pulse output that is 10 times the accuracy you are seeking. If
> you want accuracy of .001 inch you will need an encoder that has a
> resolution that will give you 10 pulses per .001 inch of travel when
> coupled through the gear reduction and encoder decoding_"
>
> My question is this:
>
> Is this true with all servo setups, and if so, why?

This is an over generalization, but has some truth in it. But, it doesn't
apply to all cases. Where it comes from, is that systems which use machine
error compensation (to correct for errors in the leadscrews, mostly) need
to have much finer resolution, so that tiny increments can be added to
the commanded position to correct for leadscrew errors.

If you are not using machine error compensation, then this requirement
for additional resolution doesn't apply. Now, if you will be doing high-accuracy
contouring, circular interpolation, or interpolating for a part placed randomly
on the machine (axis compensation), then you may still need this to get
fine positioning or smooth motion at very slow speeds.

Jon