Re: [CAD_CAM_EDM_DRO] Re: Synchronizing two motors on the same axis

John,

I would prefer to have some kind of home sensor on the two spindles to be
synchronized. If you drive two steppers, and they get out of sync for any
reason, then you will lose the alignment between the motor shaft angles.

I am assuming that not only the speed, but also the shaft angles must agree.

If anything happens that causes the motors to lose angular synchronization
(such as, with the power off, the bobbin being turned, or the needle
dropping lower, or ... who knows), you will not have an automatic way to
regain angular alignment.

What speed do you need from these mechanisms? If you are using stepper
motors, you might have troubles with the top end.

Either way, servos or steppers, I think you're likely to want to be able to
control them separately -- if for no other reason than for helping to being
them back into alignment after a fault. I don't know what the mechanical
dynamics of sewing are, but you might also find it helpful to be able to
change the relative shaft angles as a function of the operating speed or
the material being stitched (just a guess, but it would be interesting to
watch the needle/bobbin interaction under strobe light and look for phase
delays).

Just my thoughts,

-- Carl

At 04:16 PM 5/13/02 +0000, you wrote:

>Hi John
>
>I simply have a Y cable between my PC interface and two motor drivers
>for the x axis on my plasma table. As long as you are not losing
>steps it works just fine.
>
>Ron
>
>--- In CAD_CAM_EDM_DRO@y..., "j.guenther" <j.guenther@v...> wrote:
> > Here is my question for the day, what would be the best way to sync
>up two
> > motors on the same axis. It can be considered that full cycle for
>each part
> > of the axis equates to 1 revolution of each motor. The application
>would be
> > for a long reach sewing machine for quilting. I am thinking of
>driving the
> > needle mechanism with one motor and the bobbin mechanism from
>another motor.
> > If that is the route I take, these two drives must remain in
>perfect sync
> > with each other. I am assuming that either steppers with encoders
>or servos
> > can be used to accomplish this task, I am just not sure how to sync
>them up.
> > Can they both be driven from a single axis (Z) or do I need to use
>two axis
> > (Z, A) and slave one to the other? What software would be best to
> > accomplish this task?
> >
> > Thanks
> >
> > John Guenther
> > 'Ye Olde Pen Maker'
> > Sterling, Virginia
>
>
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Carl Mikkelsen
Oasis Semiconductor, Inc.
201 Jones Road
Waltham, MA 02451
(781) 647 8775