The Animatronics Workshop

Paul H. Dietz The Animatronics Workshop

Hopkinton, MA 01748 paul@animatronicsworkshop.com

Catherine Dietz The Animatronics Workshop

Hopkinton, MA 01748 cathy@animatronicsworkshop.com

ABSTRACT

The Animatronics Workshop is an extracurricular activity where kids build complete robotic shows. Designed for 11-14 year-olds, the program emphasizes the interplay of technical and artistic skills. Activities include a mix of character development, script writing, design and construction of robotic mechanisms, voice performance, audio editing, set design and construction, and motion programming.

Keywords Animatronic, Animatronics Workshop

1 INTRODUCTION In the United States, most children receive instruction in very distinct classes. Math. Science. Art. Shop. English. Etc. This has been our system for generations. And one can argue that it served us well in an era of factory work, when most people had very well specified jobs. They did one thing, and they did it well. Nicely compartmentalized courses just seemed natural.

In our post-industrial society, things are different. More and more people work in jobs that require a constantly changing mix of skills. For example, a modern filmmaker may find herself discussing the virtues of different CPUs for render farms or the physics of particle systems. The local crafts storeowner may need to master web technologies in order to grow his business.

Clearly, today’s jobs require a greater understanding of technology. But ironically, many of today’s technology jobs require a deep understanding of aesthetics. It is difficult to imagine an ugly cell phone or music player being a commercial success. A General Motors executive recently noted, “GM is ultimately in the fashion business” [Szy2003].

Given the increasingly cross-disciplinary nature of modern employment, it stands to reason that our educational system should provide more opportunities to think across fields. This is the goal of our program – to give kids a chance to experience a significant interdisciplinary project that requires the tight integration of both artistic and technical skills.

In this paper, we will discuss the Animatronics Workshop. This is an extracurricular activity for middle schoolers (~11-14 years old), sponsored by

the Hopkinton MA Parent Teacher Association. It was first developed and taught by us in the fall of 2006. For the first test Workshop, enrollment was limited to 14 children. There were 9 class meetings of 1.5 hours each.

Figure 1. Raffles is a simple 2-degree of freedom, animatronic figure based on a hand puppet. He can open his mouth (by moving the upper jaw),

and he can tilt his head from side to side.

Figure 2. The internal mechanism for Raffles.

2 ANIMATRONICS The word “animatronic” has two parts – “anima” being the Latin prefix meaning “life”; and “tronics” as in electronics. Simply stated, our goal in the Animatronics Workshop is to create the illusion of life with electronic creatures of our own design.

Many people are familiar with animatronics from the robotic entertainment displays at various theme parks. Examples can be seen in Disney attractions such as “Pirates of the Caribbean” [Pir2007] and “The Enchanted Tiki Room” [Tik2007]. These are elaborate displays built by artists and engineers at great cost. A key constraint for these displays is that they must be highly reliable. Some of these displays have run for many hours every day for decades.

Thanks in part to interest generated by Dean Kamen’s FIRST Robotics program [FIR2007], a wide array of hobbyist robotics supplies are now commonly available. When combined with appropriate software, hobbyist-level animatronics are easily accessible to non-professionals. In fact, it is possible to create displays of substantial complexity very inexpensively. The main difference when compared to professional displays is that hobbyist displays will typically use inexpensive actuators which do not have the reliability required of theme park displays.

Most importantly for us, the tools of hobbyist animatronics have gotten simple enough that the typical 11-14 year old child can master them. We came to this startling realization when our 10-year old daughter expressed interest in creating an

animatronic figure. Working with her, we were able to create a figure and a complete show in a single long afternoon. The creation appears in Figure 1 and Figure 2.

3 THE WORKSHOP The Workshop began with a broad overview of the entire process of creating an animatronic show. Using Raffles, we quickly put together some simple test shows to demonstrate the software chain. Then we examined the mechanism for this particular character, discussing all of the requisite pieces.

An early focus of the Workshop was character development. We split the class into three groups, giving each a different hand puppet. Each group imagined a personality for their character, and explored what sort of motions would be needed to best express their chosen personality. This is challenging because they are limited by what they can reasonably build. Looking at different mechanisms, we quickly settled on a fairly small set of simple, yet highly expressive motions. In accomplishing this task, the kids got their first exposure to how artistic and technical constraints can be highly intertwined.

Building the mechanisms was a challenge for the kids. Most had no machining experience, so we gave explanations of materials, tools, and techniques. After building a simple test piece (Figure 3), we began construction of the actual mechanisms (Figure 4).

Figure 3. A simple test piece. This might be part

of a mouth mechanism. Note how the aluminum is attached to the servo horn. The center hole allows

the servo horn to be removed and repositioned.

Mechanism construction took several sessions. During this time, we started discussions about the show itself. Using the personalities they had created, a script slowly evolved. Drafts were posted on our course website and all were encouraged to make contributions. In practice, this was less effective than we had hoped. While many suggestions were offered, none took the time to actually write sections of the

script. In future classes, we hope to incorporate script writing as an in-class activity.

Figure 4. A simple 3-degree of freedom (lower

jaw, head nod, and head turn) mechanism using a Lynxmotion pan-tilt bracket (black pieces). All

other pieces were created by the students.

Once the script was determined, we held auditions for the speaking roles. The kids who chose not to audition served as the judges. Recording sessions were held outside of the normal meeting time, one child at a time, to minimize background noise.

The final sessions of the class were devoted to constructing the stage, mounting the characters and the electronics, and programming the motions. Each group programmed the motions for their character. This is a straightforward process of recording the motion tracks for each actuator as they are controlled in real-time via a joystick.

At the end of the last class, we had a public presentation for friends and family. The kids were understandably proud of their creation.

In the following sections, we discuss some implementation details.

4 CONSTRUCTION One of the keys to running this Workshop was choosing materials, tools and construction techniques that were amenable to kids. Our mechanisms consist of 1/16” aluminum skeletons with model airplane servomotors serving as the actuators.

Figure 5. Building a mechanism.

The choice of 1/16” aluminum allowed the use of kid-friendly hand tools for most operations. It can easily be cut with hacksaws (Figure 5) and hand nibblers, and holes can be created with hand punches. Aluminum strips can be bent by hand against smooth curves. For sharp bends, we used an inexpensive vise brake. We also made use of pre-made brackets from Lynxmotion [Lyn2006], which greatly simplified construction (see Figure 4).

Model airplane servomotors contain a motor, a gear train, and a control system. They are commanded to turn to a particular angle and typically have a range of 90-180 degrees. Commands are given by sending pulses of varying width, with the servo moving proportional to the width of the pulse. Thanks to the massive gear reduction, they have quite a bit of torque for their small size, generally on the order of 10’s of oz.-inches.

All of our mechanisms have been simple direct drive designs. (No belts, gears, joints, etc.) To mount the aluminum to the servo, we punch holes through the servo horn (this is the plastic piece which rotates) and directly attach the aluminum with screws. It is important to leave an access hole so that the horn may be removed and repositioned. This is shown in Figure 3.

Our show has an off-stage character that is expressed through audio and changes in the stage lighting. To create the appearance of stage spotlights, we used 12V garden spotlights. These are the right scale for our setup, are fairly bright, and are easy to control.

5 ELECTRONICS Animatronic shows are generally fully automated. This is true in our case as well. We use a standard Windows-based PC running animatronics control software. The computer provides the audio tracks and sends data to a servo controller that in turn connects to the servos.

There are a number of manufacturers that make servo controller boards. Unfortunately, most require serial interfaces, which are typically unavailable on modern machines without using a special adapter. We chose to use the Pololu USB 16-Servo Controller [Pol2007]. To control the lights, we created a custom board that presents a servo-style interface. Thus, the lights can be controlled in exactly the same way as the servos.

To power the system, we used a number of surplus desktop supplies. A single 5V, 8A switching supply powers all of the servos, while two 12V, 4A switching supplies power the lights. In our experience, it is important to choose supplies that recover gracefully from short circuits. (These tend to happen when wires accidentally rub against moving metal parts.)

6 SOFTWARE To control our animatronic shows we used Visual Show Automation (VSA) [Bro2007]. It is a product of Brookshire Software, and is modestly priced.

VSA lets you create control tracks that are synchronized with an audio track. It also includes a tool for automatically generating a control track that follows an audio signal. This is used for creating synchronized mouth motions. Control tracks can also be generated by manually placing events, or by capturing joystick movements in real time.

To use VSA for a multi-character show, one needs to create a separate audio track for each character, as well as a full mix track that contains all of the audio (including all of the characters, background music and effects). The character audio tracks are read in, one at a time to generate the mouth movements for each character. Then the full mix track is loaded. The remaining control tracks can then be programmed one at a time by capturing joystick movements while all the completed tracks are played back.

To create the audio tracks, we used Apple’s GarageBand [Gar2007]. This is a reasonable package for editing back and forth dialog. It comes with

prerecorded loops and sound effects that proved useful. We also took advantage of the noise reduction and pitch shift capabilities.

While VSA gives some user adjustable parameters for generating a control track from audio, we found it useful to purposefully distort the audio before bringing it into VSA to get the appropriate effect. We used Audacity [Aud2007] to heavily normalize the volume levels, which helped maintain reasonable mouth movements during quieter passages.

7 PERSPECTIVES Our first show, shown in Figure 6, was called “Perspectives” and featured three animatronic characters: a cat (Kit Mouser), an elephant (Packard A. Derm) and a pig (Pignella Hamswell). The show roughly follows the format of a Sunday morning news talk show. Each character has three degrees of freedom, giving nine motion control tracks. Each of the four spotlights also has a control track, bringing the total to thirteen. On the audio side, there were seven tracks (the animatronic characters, backstage characters, music and sound effects). “Perspectives” runs for about 12 minutes. A video of the show can be found at:

http://www.AnimatronicsWorkshop.com.

Figure 6. “Perspectives” – a 12-minute show

featuring 3 animatronic figures

8 FUTURE WORK The Animatronics Workshop is a work in progress. We would like to expand the program in length and scope, and help bring it to other schools. As noted, we would particularly like to increase the opportunities for story and script development. There are interesting pedagogical opportunities in this area. Animatronics are a delightful presentation tool, and it would be great to see students writing educational scripts.

Ultimately, the most interesting future work will not be ours - it will be that of our students. We already have reports of our students using their newfound animatronic skills in their regular classes. Examples

range from simple tasks (how to file, or how to draw an ellipse with a piece of string) to a science project that uses computer-controlled servos. The interdisciplinary nature of the class encourages kids to take what they know and use it elsewhere.

9 CONCLUSIONS We believe the Animatronics Workshop provides a fun and exciting way to introduce kids to cross-disciplinary projects. In a very short time they can create a complex robotic show that compares well with professional theme park experiences.

Figure 7. Participants in the first Animatronics

Workshop with their creation.

10 ACKNOWLEDGMENTS Obviously, this would not have happened without the kids and parents who helped make this program a success. We would also like to thank the Hopkinton

Parent Teacher Association for sponsoring this program.

11 REFERENCES [Szy2003] Szygenda, R., “Business-Technologist

Visions: It's A Great Time To Be In I.T.”, InformationWeek, Jan 27, 2003, available at: http://www.informationweek.com/story/IWK20030124S0022

[Pir2007] Walt Disney World’s “Pirates of the Carribean”, http://disneyworld.disney.go.com/wdw/parks/attractionDetail?id=PiratesoftheCaribbeanAttractionPage

[Tik2007] Walt Disney World’s “The Enchanted Tiki Room”, http://disneyworld.disney.go.com/wdw/parks/attractionDetail?id=TheEnchantedTikiRoomUnderNewManagementAttractionPage

[FIR2007] FIRST – For Inspiration and Recognition of Science and Technology, http://www.usfirst.org

[Pol2007] Pololu Robotics and Electronics, http://www.pololu.com

[Bro2007] Brookshire Software, http://www.brookshiresoftware.com

[Aud2007] Audacity: Free Audio Editor and Recorder, http://audacity.sourceforge.net

[Gar2007] GarageBand, from Apple Computer’s iLife package, http://www.apple.com/ilife/garageband/

[Lyn2007] Lynxmotion, Servo Erector Set, http://www.lynxmotion.com/