Re: Why is the push to such high step rates (Grex and Arc100)?

We really do need very high feedback resulutions/pulse frequencies.
The actual resolution required for a dynamic servo system is MUCH
higher than the required machining tolerance. I believe the rule of
thumb is 10x higher but more is better. As mentioned earlier, modern
servo drives do not use tachometers to measure velocity. The digital
controller/drive must see multiple encoder counts to determine
velocity, and more still to calculate acceleration. These values are
pushed into the feed forward loops to maintain position even during
high accelerations where a typical PID loop may not be sufficient. I
think it is the end goal to have Mach-3 come as close as possible to
one of the expensive commercial systems from a company like Fanuc. If
that is what we're going for, then we need all the help we can get :)