Motor control X Y Z

Motor wrote:


"beamer"?  I gather from context that you don't mean a BMW.


If you have three independent axes you need to control you need at least
three independent actuators -- just like high-school algebra, where
three unknowns required three equations.  If you want to control
direction as well as offset you'll need more motors.


As Windows gets more and more in the way between your software and the
real world even stepper control gets harder and harder.  I'd suggest you
look at "Nuts & Volts", "Servo" and "Circuit Celler" magazines -- all of
these have information and projects regarding the kind of basic stuff
you want to do, and they should all have USB thingies for sale in the
back to do what you want.

Stepper motors are easy to control, and they hold their position when
you remove power.  That's about the only good things I can say about
them.  They're big for their power output, they have limited accuracy*,
they aren't forgiving if you ask more from them than they can deliver.

While there are applications for which steppers make good sense, you
should make sure that this is one of them before you rule out using a DC
motor in closed loop.

For this sort of thing you may be best served with some little
motion-control modules that drive the axes to where you want them,
controlled from an executive in the PC that just decides what the motor
positions should be and transmits the data.  If there isn't a
USB-commanded servo controller out there, someone's working on it.

* unless you start microstepping them in which case they're less easy to
control.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Posting from Google?  See http://cfaj.freeshell.org/google/

Here is one website to get some information from.:

http://www.galilmc.com/index.html

.... I'm not sure if these devices are cost effective, but they seem to have
various capabilities.

Dave

Rather than re-invent the wheel, you could always purchase a camera pan-tilt
head on Ebay and mount the projector on that.. The higher-end ones come with
either serial or Ethernet comms.

HTH,
Cameron:-)