Re: Announcement: Mach3 is now closed loop!

I prefer to think of it as 'tightly-coupled' versus 'loosely-coupled'
feedback loops. The difference is the degree of latency (delay)
incurred.

Imagine you are racing a slalom course. If the steering wheel
responds in milliseconds to your input, you'd probably do OK. If it
took a few seconds to respond, you would certainly zag where you
should have zigged.

Same thing here; the amount of latency determines what can be
accomplished. A tightly-coupled feedback loop can respond 'real-time'
to changes by modulating motor/drive input as a correction. A loosely-
coupled loop is much more limited; it can only monitor but not
correct motor/drive behavior. It is an 'after the effect' thing. Kind
of like airbags for when you crash because you zigged when you should
have zagged.:-)

Mariss

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@p...> wrote:
> Alex Holden wrote:
>
> >On 26 Jul 2005, at 13:24, Thom Carr wrote:
> >
> >
> >>At some point, it would be time to use new defining terms for
both
> >>"Cosed Loop" systems. Something like Closed loop/ correct and
> >>Closed loop/ detect.
> >>
> >>
> >
> >Closed loop is a well defined term in control systems engineering.
I
> >would say the new Mach3 feedback feature is open loop with error
> >detection. It's not closed loop in the conventional sense that
it's
> >able to modulate the power supplied to the motor based on how far
> >it's lagging behind (or ahead of) the expected position, but at
least
> >it is able to notice and stop the system (hopefully before
trashing
> >the workpiece) if the steppers lose steps.
> >
> >
> >
> Yes, I agree with you, but got yelled at by several people for
> making this distinction. 1/10th of a second on a router is a
pretty big
> disaster, I suspect.
>
> Jon