RE: [CAD_CAM_EDM_DRO] Re: breakout boards plus - hard choice

Hi Jon

The G100 just has step direction output, and encoder inputs, it does have
internal processing power, and it does command the step federate so it could
detect and error and slow things down. However when released the firmware
with the G100 had many many fault, Mariss coped out saying he was not a
programmer, so I very much doubt he has implement a closed loop himself
within the G100. The guy that now develops the G100 firmware Stephen, is a
good programmer, but he is generally very vocal when he gets a new trick
running, and we haven't heard from him regarding this.

I am still fairly sure Mariss is looking at the current response to a pulse
and from that determining impeding failure of a step so he knows when to cut
back the feed rate and store pulse errors with his stepper card. It's been a
long time since I studied steppers, but if memory serves me right as you
load a stepper, the current lags and the crest factor changes, just before
stalling there are massive crest factor changes.

Regs Mark



Dr. Mark Vaughan Ph'D. B.Eng. M0VAU

Managing Director

Vaughan Industries Ltd, reg in UK no 2561068

Water Care Technology Ltd, reg in UK no 4129351

Addr Unit3, Sydney House, Blackwater, Truro, Cornwall, TR4 8HH, UK.
Phone/Fax 44 1872 561288

RSGB DRM111(Cornwall)

_____

From: CAD_CAM_EDM_DRO@yahoogroups.com
[mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of Jon Elson
Sent: 20 July 2007 02:28
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: Re: [CAD_CAM_EDM_DRO] Re: breakout boards plus - hard choice



Mark Vaughan wrote:

> You may be right Jon, but I thought Mariss's break through was being able

to

> detect the load problem before loosing steps without an encoder.
>
> Really if he's done it with an encoder that's a pretty simple task and not
> worthy of all the hype.

No, it IS a bit tricky to detect the impending stall and catch
it BEFORE the stall ocurrs, and hold the drive right at that
point where delivered torque is at the maximum.

I am absolutely certain that an encoder is used, but it doesn't
feed back to the DRIVE, it feeds back to the controller, which
would be the G100 in this case. The G100 sends more detailed
info than just step/dir to the drive, it has to send a current
command, too, if I understand what Mariss has done.

What I understand of this may also be just what Mariss grabbed
off the shelf at Gecko Drives to make a test bench for the
project, and may not actually apply to what he intends to use in
the final product.

Jon





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