Re: 20 Amp 80 V $99 DC Servodrive

--- In CAD_CAM_EDM_DRO@egroups.com, Jon Elson <jmelson@a...> wrote:

>
>
> Mariss Freimanis wrote:
>
> > The PID circuit of the G320 is an analog implementation. The
> > proportional and derivative co-efficients are set via two

screwdriver

> > adjustable trimpots marked "GAIN" and "DAMPING" respectively.
> >
> > Command the motor to turn about 60 RPM and toggle the direction 1

to

> > 2 times a second. This will place an impulse load on the motor.
> > You set the "GAIN" to the desired stiffness and then adjust
> > the "DAMPING" until there is no "ringing" or oscillation.
> >
> > This is easy to do with the G320. It is tolerant of misadjustment.
>
> Gasp! That may be a good test routine for a motor held securely in

a

> vise,
> but it would be a big mess on my Bridgeport. I had a positioning

loop

> oscillation in my early setup of my servo amps, and the entire 1800

Lb.

> milling machine started to rock from side to side. It was in the

range

> of 2 Hz. I had to hit E-stop and turn down the gain before trying
> again.
>
> Jon

You are right, I hadn't thought of that. You would want to introduce
a much smaller transient than that. It is necessary though to elicit
loop response in order to set compensation to critically damped or
slightly underdamped. But use a MUCH smaller transient though.....

Mariss