This is an end-to-end example using a DeVaSys I2C/IO USB board. The board controls two servos, one for horizontal movement and the other for vertical movement. A web interface allows horizontal, vertical, and diagonal camera movement - remotely. Thats right, the USB board and camera can be connected to a machine at another location and controlled remotely.
The pictures below should provide enough detail to get you going in the right direction. A Lego MindStorms Vision Command and a Lego Creator set (model 4120) were used to create Waldo. The README.txt in the source (Ezusb2131/Examples/Waldo) contains detailed instructions on things I did to get this working. Click on an image below to get a more detailed view.
The base.
Walls added to base.
Horizontal and vertical servos. JB Weld (super strong epoxy - IMHO the best
there is) was used to bond the Lego parts to the servos. It
is very important the Lego parts are attached perfectly straight.
The discs the Lego parts are JB Welded too are not screwed to the
servo shaft. I placed a small piece of cellophane over the screw hole
to prevent the epoxy from bonding the disc to the shaft - I can
remove the disc and use the servo for other projects.
Futaba FP-S148 servos were used.
A Lego post was attached to the vertical servo, and a Lego spacer attached
to the horizontal servo. Yes, over-kill on the JB Weld here - I mixed up more
than I needed... Notice the holes through the yellow blocks, this is
how the vertical servo is attached to the frame. If you look close you'll
notice the SuperLock (velcro) (RadioShack Cat# 64-2360) has been JB Welded on
the vertical
servo. This was done because the slightest movement between the servo and the
base allowed the gears to slip at extreme angles.
The bottom view.
The top. The silver rods are actually made from a crochet needle
(aluminum size US:7). This is constructed from the MindStorm Vision
Command set. Notice the crochet needle being used as a brace (JB Welded)
between the upper and lower segments.
The base with the board in place. The black top portion is from the
MindStorm Vision Command set
The base, board, and top in place. Notice the crochet needle through
the yellow block attaching the vertical servo to the frame.
Everything but the camera.
This is Waldo!
Yes, I could have gotten by with a couple servos, duct tape, and a little
JB Weld.
While it would have been functional, it wouldn't have been at all presentable.
So if your just looking for functionality, theres no need for the Lego
sets IMHO.