Re: [CAD_CAM_EDM_DRO] Re: stepper vs servo

ddgman2001 wrote:

>If the feedback goes to the gecko unit, how well does it handle
>error compensation?
>
>

What is error compensation? Since it is an open-loop system, the CNC
computer has no idea how close the actual position is to the commanded
position, ather than knowing it is within 128 encoder counts, as exceeding
that will cause the gecko servo to fault. Within the 128 counts, a PID
(Proportional, Integral, Derivative) feedback control loop is implemented
in hardware to give stable and smooth following of the commanded
position.

Do you mean compensation for backlash? That can still be handled in the
software.

Do you mean feed rate compansation
(slowing down all other axes to accomdate one axis that is lagging behind)?
With no feedback to the CNC control, that can't be done.

Do you mean machine error compensation? That is done by a table in
the CNC control's memory, that knows how many thousandths to add
or subtract for certain ranges of position of each axis. That can still
be done in software.

Jon