I built the Imperial Melody Discharger, an articulated Stormtrooper helmet music box, for the Star Wars Day ("May the 4th be with you") vinyl Stormtrooper helmet art show . For the event, artists across the Walt Disney Company, including DisneyToon Studios where I work, were invited to participate by using a blank 6" helmet as the canvas for their work. What follows are my build notes and work in progress images.
My intention for the piece was to provide a view behind the mask of the anonymous Stormtrooper, while creating a fun, interactive moment for the person experiencing it. I wasn't sure exactly how to get there, but I was certain I'd need to cut the vinyl helmet open. You only have one shot at that, so I decided to first cut apart a CG model inside Maya, and rig it with pivot points that could be used in the real world for the facial articulation.
Mostly satisfied that I knew where to separate the parts of the helmet, I grabbed an X-acto knife, took a breath, and began the incision. (Note: It smelled really foul in there. Also note: I have no way to compare the smell to that of the insides of a tauntaun.)
Once splayed out I wasn't too surprised to see that the "pelt" of the helmet was darned floppy. I needed to build an armature to keep the structure solid, and to support the articulation of the two halves of the face mask.
With very little time to get fancy building parts from scratch, I rummaged around my workshop, closets, and shamefully disorganized garage, until I came upon an old spider Babyface homage to Toy Story I'd build back in '95 out of Erector sets. Sorry, Spider Baby, I needed your body parts.
Please look away if you're an Erector set purist. I bent and cut up some beams to fit my needs, and then laid out the basic support structure.
With some drilling and bolting I got most of the helmet secured to the armature. Needing a secure bond between the eye sockets and the ends of the metal beams, and not wanting to place screws through his eyes, I referenced ThisToThat.com to learn that Houshold Goop is recommended for adhering metal to vinyl. I glued the parts together, added a small magnet to each tip to aid with closure, and clamped them with clothespins to dry.
My next task was figuring out how to make the two halves of the face mask move. I knew from the CG rig I'd built in Maya that I could fit two standard hobby servos, plus a microcontroller, and batteries inside the helmet. A pair of directly coupled servos would be simpler than building a gearing mechanism to swing the two "arms" of the mask from a single motor, plus I could vary the timing of the two halves for added dramatic effect. I did some quick tests with one servo opening and closing half of the mask and it worked well. I discovered that by pivoting from two points on the servo - one lower attachment flange and the control horn, I could swing a wider arch and avoid pinching the hinge of the mask. This dual pivot worked somewhat like a clavicle and shoulder when raising your arm out to the side and up.
For the brains of the operation, I used an Arduino Uno microcontroller with a prototyping shield. Onto the shield I soldered cable interconnects, a piezo buzzer, and a Pololu Pushbutton Power Switch for power management. I programmed the Arduino with a small bit of code (available here) to wait for a button press, open the right half then the left half of the mask, play the Imperial March theme on the piezo buzzer (for nostagic/crappy sound quality), and finally close the two mask halves. Since I wanted to run the piece from four AA batteries, I didn't want them to drain when idle by having the Arduino constantly powered on, waiting for the interaction button to be pressed. The Pololu switch solved this neatly - it acts as a power switch, but can itself be controlled by the Arduino, so at the end of my entire routine, the Arduino sends a command to the Pololu switch to power down the board.
I noticed that the skull cap was pretty floppy and looked unfinished. A trip to my favorite local odd-parts store, Luky's Hardware , yielded a nice aluminum hose clamp, which I also glued in place with the Houshold Goop.
Breaking out the X-acto knife again, I cut out a spot for a panel-mount LED indicator light. This would be used to signal when the Melody Discharger's button had been pressed and the system was active.
I mounted a battery pack inside the skull cap, and then marked and cut out a hole for the shiny, red interaction button.
I patterned and cut out some thin sheets of steel to cover the eye lenses of the mask, giving them a bit more life than the blank, matte white of the vinyl. I glued these in place.
I then plugged the button, LED, and battery pack into the Arduino, and closed the whole thing up.
I'm very happy to say that my Imperial Melody Discharger (named by my friend Mike Greenholt) was a big hit with patrons at the show opening at the Robert Vargas Gallery in Downtown L.A. I was thrilled to watch people interact with it and smile.
Catch the show for one last day at Robert Vargas Gallery, Sunday, May the 4th, 12 - 4 pm