Re: [CAD_CAM_EDM_DRO] Re: Re: Re: GeckoDrives.. Can anyone Help?

Tom Eldredge wrote:

> Jon Elson,
>
> Thanks for clarifying yesterday's email. So the tach is the real missing
> link.
>
> Understanding what you do about this situation and the Gecko drives, do you
> think Mariss could add tach feedback to his amps also?

Yes, to the linear input servo amps that are in the works, only.

> If he, say for
> example, added DC tach feedback from the motor to the G340 amp, would we
> then be able to say we have true velocity control?

No, because the velocity info is not sent from the computer to the G340 drive.
It still has ONLY position info, and no way to tell instantaneously what velocity
the CNC control wants now. Adding tach feedback to a stepper and direction
drive does not fix the problem.

> It seems I remember Mariss saying something about making a velocity drive
> sometime in the future. I wonder if this is what he is thinking of. I am
> going to do a search on his emails to see if my memory is showing its
> weakness again.

Yes, he has said this is in the works.

> I was under the impression that the multiplier on the G340 drives only
> allowed one to use the higher count encoders found in retrofit situations.
> It does not do anything for us in the way of smoothing out the motion does
> it?

Yes, it does smooth out the motion a bit, since the steps that are commanded
will be of the resolution on the encoder, not the larger steps coming out of
the computer. But, if the computer is generating 5 steps a second, and the
multiplier is set for 10, then the motor will be moving in ten encoder count
bursts 5 times a second, and pausing between them. A true velocity servo
system will move at a smooth rate covering 50 encoder counts every second.

Jon