art robot

[the process]

Once we started in to begin making art robot, it was clear that the first step
would be to build the structure that would hold the reflection center. We thought
of this as analogous to starting with the heart of the robot, as the reflection
sensor was going to be central to the project. (We quickly took to calling the
structure that housed the reflection sensor the scanner, and have continued to
call it this for the duration of the course.)

The early iterations of the scanner are much more simple than what we eventually
ended up using. There are several reasons for this: as the project progressed, we
decided that the scanner would be the location of a number of other important features
to Art Robot, in addition to home of the reflections sensor. A motor (to move the
scanner east and west across the image), the Handyboard, the stippling structure
and another motor to power the stippling structure, would all be located on the
scanner. Needless to say, this added considerable bulk. Further, once we added all
of these features to the scanner, a great deal of reinforcement was necessary to
keep the scanner intact. We had to add metal wheels to the base of the scanner so
that most of the weight of the structure would rest on the ground and not on the gear
track along with the scanner moves. Also, the gear system inside the scanner, that
moved the scanner along its track, had to be continually adjusted so that the scanner
moved at an appropriate speed. We added a number of larger gears and a worm gear to
slow down the movement of the scanner.

As our scanner enlarged in size, so did the frame that contained the original image.
Our initial design for this part of Art Robot was fairly simple: two tracks on each
side of the frame for gear wheels to move along. The gear wheels would attach to the
scanner to move it in the north and south directions. We planned to power the wheels
with a motor that would turn on for a very brief amount of time each time that the
scanner had completed scanning one row. This would move the scanner slightly over
in one direction so that it could begin scanning a new row. This remained the underlying
objective, but the engineering necessary to achieve this objective turned out to be
considerably more complicated.

Right away, we realized that we had to slow down the speed at which the scanner would
move. Even with the motor running for a split second, the scanner would move much farther
than we wanted it to. Also, we quickly realized that our design would not be robust
enough to move the ever-growing scanning structure. We would have to build a very sturdy
frame in order to control the north/south motion of the scanner. Instead of powering
the gear-wheels directly with a motor, we decided to install a system of worm gears
running parallel to the track that the gears would move along. By doing this, we could
slow down the movement of the scanner and install a motor at one end of the frame to
turn the worm gears and thus move the scanner. The worm gears also help keep the gear
wheels in place. After some experimentation of what kind of gears to use to move the
scanner, we found that the gears with the claw-like notches worked the best; they caught
the worm gears the best, providing the most reliable and consistant movement.

The decision to mount the stippling machine on top of the scanner came from our aversion
to building a second frame. We found it daunting to design a frame that could move the
stippling machine in exact correspondence to the scanner, so we decided to include both
features on the same structure. By using plexiglass and tracing paper, viewers could still
see what Art Robot was up to even though the action would be taking place on the underside
of a raised platfom. We build four "stands" to hold the plexiglass above the stippler,
and keep it in place.