RE: [CAD_CAM_EDM_DRO] Considering new servo product!

Going from PMDC brush type motors to Brushless in order to handle the
commutation, you might need to either do trapezoidal phase advance using the
hall effect sensors or do a sin look up to get a smoother sinusoidal
commutation. In either case the brushless case is a bit more complicated
than the more straight forward brush type implementation; not necessarily a
small step up IMHO
Madhu

>-----Original Message-----
>From: Jon Elson [mailto:elson@...]
>Sent: Monday, October 06, 2003 12:24 PM
>To: CAD_CAM_EDM_DRO@yahoogroups.com
>Subject: [CAD_CAM_EDM_DRO] Considering new servo product!
>
>
>Hello, all,
>
>After corresponding with John Kasunich about PWM and servo amplifiers,
>an idea ocurred to me. I can make a modification to my existing Universal
>Stepper Controller board (entirely by changing the configuration PROM)
>that will make it put out PWM and direction instead of step and direction.
>I could make a very simple servo amp that takes in PWM signals, and doesn't
>have much smarts other than current limit and fault trip. This should be
>pretty cheap to make. If I can do enough with the PID parameters in
>EMC to get good response and stability, this should make a VERY simple
>and cheap closed-loop servo system. And, if I can do DC brush motors,
>I could then expand it to permanent magnet brushless motors (often
>called DC brushless) too. That would cost 2 more power transistors,
>one more half-bridge driver, and a few CMOS chips.
>
>This DOES give up some smoothness at the very low speed end, and could
>run into trouble if there is a lot of spring in a thin leadscrew or some
>other
>mechanical pole in the response. But, it should work as well as a Gecko
>320, since that is what they are doing in hardware. Plus, all the
>parameters
>will be accessible from software. It also makes it possible to go
>to higher
>voltages and currents than the Gecko can handle.
>
>This would also allow me to offer a complete package all from one source,
>and to offer kits (all the complete and tested boards, no box or power
>supply)
>as well as complete NC driver boxes.
>
>Any comments?
>
>Jon
>
>
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