44 SERVO 04.2016
This clever design
has been high on my
wish list since I came
across it during one of my “researching sessions” on the
Internet. This electronic solution was something I was
extremely interested in and excited to put to the test. It is
certainly a unique and groundbreaking approach.
The original concept for this project was the ingenious
brainchild of David Boccabella, a.k.a., Marcwolf. His original
concept was to have a screen display the image of the iris
and dilating pupils by using multiple bitmaps. He planned to
use plastic eyes and employ a gimbal mount to adjust their
gaze. A link to his site detailing his original plans can be
found at http://tinyurl.com/jgo7kvw.
His prototype design was seen by Phillip Burgess, who
offered to furnish some alternate code. His continued
contributions have afforded some significant improvements,
including eyelids that blink and a moveable gaze. The
directions written by Burgess — which can be found on the
Adafruit site (see Resources) — are thorough and easy to
follow. For my purposes, I went with the basic setup of the
Teensy board and two eyes. His instructions incorporate the
ability to add extra features, as well.
These include the ability to add a joystick to control
movements and a photocell to enable the pupils to respond
to varying light intensities, as well as the option to control
the eye blinks using buttons.
There are two styles of screens available. You can elect
to use the OLED breakout boards which look fantastic, but
they are expensive at $39.95 each. The other option is to
utilize the TFT LCD displays which cost much less at $14.95
each, but you will sacrifice some of the vibrant colors
available on the more expensive displays. You will need to
decide if your application warrants the extra expense for
the OLED displays.
The program supplied with the tutorial has the
option of running one of four different eye
designs. For our purposes, we decided to use the
dragon eyes (Figure 9). It was a simple matter to
follow the instructions, comment out the default
eyes, and enable our selection.
A supplementary option in the tutorial was
the inclusion of the necessary files to print 3D
enclosures for the screens. I decided to use these
along with the suggested eye blanks as I think
they add a significant amount to the effect. I do
not have a 3D printer, nor do I have easy access to
one. However, I have wanted to give Shapeways
(see Resources) — a popular online producer of
consumer designed 3D parts — a look, and this was the
I simply uploaded the supplied file from the tutorial,
picked the product I sought to use (black, strong, and
flexible), and ordered them. A short time later, they were
delivered to my doorstep (Figure 10).
The quality was even better than I expected and the
process could not have been easier! I would recommend
them to anyone interested in getting started with 3D
printing before you make the investment in your own
printer. Now that I have tried it, I will be utilizing this
process much more often. Maybe it is time to consider
getting a 3D printer of my own!
The one thing I quickly discovered when soldering the
ribbon cable to the first eye was to not cut all the wires the
same length. If you are using the 3D printed holders as I
did, there is a very limited amount of space for the wires.
They need to be able to lay flat and side by side, so each
wire needs to be cut to the proper length before soldering
them to the board.
There is some
fairly fine soldering
involved, so a
tweezers will both
come in handy. A
steady hand is also
going easy on the
taking up my
choice has been
the PICAXE chip; it
is easy to program
and has plenty of
Figure 10. 3D enclosures and eye
Figure 9. It is alive!
they mean it!