Re: [CAD_CAM_EDM_DRO] Servo Motor Make Up?

The big unqualified answer to your question is yes, a
brush DC motor with an encoder is technically a servo.
Since there are brushes on the armature, the
commutation happens in the motor itself.

However, industrial servos are a different animal.
They are brushLESS (either AC or DC.....actually the
motors are the same, the difference is how the signal
is applied to the motor). Since they are brushless,
the commutation has to take place in the drive.

Also, the brush DC with an encoder usually doesn't
have feedback to the controller, so technically it
isn't a true servo system. An industrial servo has
feedback to the controller.

Also, industrial servos are smaller in diameter (and
as a result longer in length). The reason for this is
for better acceleration. This usually isn't a problem
for homebrew CNC.

This is a simplified answer to a question that you can
spend years researching. Baldor has a decent site for
info www.supportme.net. Also, Jacob Tal of Gallil
wrote a good book on general servo theory. Call
gallil to find out how to get a copy.



--- John Delaney <jdelaney2@...> wrote:

> I've been sloggin' through the archives back to Jan
> '04, so far.
> Things are getting repetitive but I can't find a
> simple statement on
> this.
>
> Is a servo motor simply a "normal" DC motor with an
> encoder?
>
> If not can anyone refer me to a source of
> information on them?
>
> Please advise. Thanks in advance, as always.
>
> -jd
>
>
>
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