Re: [CAD_CAM_EDM_DRO] AC servos

Graham Stabler wrote:

> I recently hit the jack pot on ebay with a pair of Parker linear
> stages, one with 1M travel, the other 0.5M, square rail, ballscrews,
> enclosed screws, really nice stuff and at a great price. I'll be
> asking for some advice later on how to turn them into something
> useful. You can see them on ebay auction 130128732978 but its hard to
> make out what's what from the pics.
>
> They have AC servo motors attached, both Omron, one is 100W and the
> other is 200W, both 200v, both 13bit incremental encoders.
>
> You can see them here:
>
> http://omron-industrial.com/en/home/products/motiondrives/ServoSystems/RotaryServoMot/default.asp
>
> SGMAH-02AAA4CD-OY
> SGMAH-01AAA41D-0Y
>
> I'd assumed that I'd take them off, replace with DC motors and use
> geckos but I had a look at the drivers for them:
>
> http://omron-industrial.com/en/home/products/motiondrives/ServoSystems/ServoDrives/SigmaII/default.asp
>
> And I noticed that there are pulse input versions of the drives. Does
> this mean they could be used with step and direction signals?
>
> I realize they are probably priced way above my budget but if they
> could be used it might be worth saving an ebay search in case I get lucky.

Sure, these are really Yaskawa motors and drives, judging by the
model numbers. Unfortunately, for their own motor/drive
systems, they use a proprietary encoder scheme, with 3 channels
containing incremental encoder plus index and commutation
signals, all decoded by the drive. So, these motors are hard to
use with other maker's drives. Yaskawa does make
industry-compatible versions of their motors.

I have used some older Yaskawa Servo-Pack drives with
step-direction signals. You lose a lot of performance with
software generated step signals because the encoder resolution
is so high. (I think they have a feature to lower the
resolution, like the Gecko's pulse multiplier module).
Or, you can use step generation hardware to produce the step
rate you need. The performance of these drives is somewhere
between awesome and frightening! I had one accelerating to 3000
RPM and stopping within a single revolution!

Yes, the Omron drives are not likely to be much less than the
Yaskawa price, which will also be frightening.

Jon