Re: mill threading, Acceleration, Axis

Ballendo,

Well, I now have a Sigmoid (tnx Dave) equation, which I thought I might
code into a table. Still several calc's to do during runtime, but this
could be an improvement! Thanks for the comments. I am seeing that
MaxNC (4-phase) doesn't get much faster then 5 IPM (even if you request
it) on the '386 I'm using for a "shop" machine. It probably DOES go
faster on a FAST machine. The step/direction probably goes faster,
also. I can get the 4-phase driver and steppers up to about 10 IPM
(without missing steps) with my code, but that's about all. Not really
important, as I don't cut that fast, but interesting "experiment". I
intend to install a bipolar motor (bigger) and drive, and see what It
will do (I will also see what the CY-545 will do!).

Alan

ballendo@... wrote:

>
> Alan,
>
> Jon already gave you some good advice. I'll add in a different
> direction...
>
> The "best" acceleration "curve" for a stepper motor is generally
> considered to be the "S" curve. This is where we start acceleration
> slowly, then accelerate the acceleration (yep, read that one twice!),
> and then do the reverse to slowly move into the desired step rate.
>
> It's two exponential curves back-to-back. The benefit here is that
> the acceleration RATE is low at the beginning and end of
> the "ramp"(curve), where the inertia of the load is against us. And
> the acceleration RATE is HIGH in the "middle" of the ramp, so we get
> to our desired rate as quickly as possible.
> <snip>
> Ballendo
>
> >In a related topic, is there a way to determine the "best"
> >acceleration curve for a stepper motor? I have an acceleration
> >table that I built based on my "understanding" of Cybernetic
> >Microsystems' CY545 chip,<s>
> >Alan
>