Re: Open (i think) design for a parallel robot (reprap may be interested)

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Mike Pogue <mpogue@...> wrote:

> I am guaranteed to always be as close to the circle in stepper motor
> coordinates as it is possible to be with steppers. It's not a PID
> algorithm, so I don't have overshoot to deal with.
>
> Note that the quantization introduced by the steppers is way smaller
> than the backlash in the mechanical stuff.

I'm just saying that the quantization exists, you said it didn't
because the number of decimal places in the control program matched
that of the steppers. There will always be some difference between
where the tool should be and where it is if the position of the tool
is discretized by steps.

I'm not saying its a problem.

The other point was simply one about numerical accuracy, its academic
but when defining a circle say in a PC even at 64 bits there is some
quantization error. Its academic because the error is smaller than
the machine resolution.

Graham