What's a PID closed-loop stepper?

Hi,

I'm a newbie, been lurking for a while.

I've seen Mariss refer to PID closed-loop stepper in a couple recent
messages. What is it? I know what closed loop means, but I understand it
in the context of a servo where an encoder sits on the drive shaft (or
driven shaft) and the driver constantly compares and adjusts desired
location and actual location. I always understood steppers to be open loop.

Also what's PID stand for?

Many thanks,
Ken

On 6/4/06, Mariss Freimanis <mariss92705@...> wrote:
>
> OK, taped it, converted to DivX, posted it. Please go to:
>
> http://www.geckodrive.com/product.cfm?pid=19
>
> Then pick 3900IPM.avi. Please download and save; view it from your
> hard drive instead of selecting "open". This will save on bandwidth
> and not irritate our webmaster.:-)
>
> Video: 16 seconds, 1.234MB, 720 X 480 format, encoded using DivX 6.0,
> no audio; had to remove it because I swore when I nearly got nicked
> by the axis.
>
> The average velocity is 51.4"/sec if accel/decel is included. The
> velocity 65.535"/sec after accel, before decel. The motor is an MCG
> IH230014 run in parallel at 3A/phase, 24VDC supply, PID closed-loop
> on the G100 driving a stock-standard G201.
>
> I'll leave the video up one week, then I'll take it down. Enjoy.
>
> Mariss
>


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