Often, the more interesting challenges that go into the film industry''s monster designs happen inside the flesh and fur and are wrapped up in size limitations, ruggedness, and quiet operation.
Many articles written about the behind-the-scenes goings-on in movies like Jurassic Park, Men in Black, Evolution, and others focus on the big models. Some are created through computer graphics (CG), but many are designed and fabricated out of mechanical components, latex, and any number of fuzzy, feathery, or scaly coverings. Once built, the 20 ft tall dinosaurs and monsters, when not CG, operate through high-powered hydraulics systems. The slithering snake created for the movie Anaconda was driven by hundreds of pneumatic cylinders. And then there are the suits that men and women wear.
Every movie set upon which a non-human star is present has a number of different models -- called creature effects, where "hero" is the name given to the most technically advanced version. Other types of creatures used on film would be those called "stunt" or "background" models. Each hero is used at different times during filming, often in separate pieces specific to the shot. The heroes we''re going to cover are the ones that operate using miniature electronic motor assemblies, called servos, similar in function to the ones in a radio-controlled car or airplane.
Craig Kackert''s business card says, "We put Muscles in Monsters." He is president of CK Design Technology and has been working in the electronics business for over 30 years and in conjunction with the special effects side of the movie business for nearly 10. CK Design manufactures and distributes proportional servo systems much like the systems used in the hobby industry. These can be controlled directly through an electronic transmission wire harness, or through radio control (wireless transmission). The biggest difference Craig''s servos have over the hobby industry is that his are for heavy-duty applications, like robotics, RPVs (Remote Piloted Vehicles) and UAVs (Unmanned Air Vehicles), animatronics, and other aerospace and commercial applications. His specialty includes customized linear actuators for all these industries, plus he supplies all the RC interface electronics and subassemblies necessary to operate his mechanical systems. Craig''s "muscles" are found in an array of heroes used in numerous films, like Jurassic Park II and III, The Relic, Alien, A.I., Monkey Bones, Rat Race, The Ghost & the Darkness, and Mighty Joe Young.
Size and Capability
What makes CK Design Technology one of the best in the business has to do with size. Craig is called in whenever design limitations creep into a project, which is pretty often, he says. For example, the baby T-Rex in Jurassic Park II: The Lost World uses several of Craig''s Mini-Linear actuators.
Stan Winston Studios, the outfit contracted to produce the dinosaurs, designed the mechanical structure for inside the baby T-Rex''s body. Preliminary meetings to discuss how the baby T-Rex might move included Craig, the Stan Winston design team, and a paleontologist. That''s when the original design concept was sorted out. Using a uniquely designed support assembly, the baby Rex legs incorporated three actuators each. The legs had to move smoothly throughout their full linear actuation. From that original concept, Craig became involved with designing the linear actuators. Once the actuators were designed, the overall size of the baby T-Rex could be extrapolated. A styrofoam version of the dinosaur was sculpted and a preliminary estimate for the actuators was ordered. When Spielberg visited the Stan Winston Studio to examine the styrofoam cutout, he said that the baby T needed to be about 20% smaller in size.
"I had already been working on the design of a Mini-Linear actuator at the time," Craig says. He then created the prototype and got the design approved. Once approved, Craig had a four-week window before the parts needed to be delivered.
The Mini-Linear incorporates a proprietary design that eliminates the possibility of back-driving the device. "This all happened during preproduction," he says. Craig went to work in his shop to design a linear actuator that could fit into the neck, leg, and tail structure of the baby T-Rex. Actuators were also used to expand the baby T''s chest cavity to look as though it was breathing.
An added benefit of the RC servo system is that no hoses or wiring had to enter the dinosaur from the outside, allowing a full shot of the baby T-Rex while the legs were moving. Craig explains, "Maxon motors are very small for the amount of power they provide, plus they offer higher efficiencies -- in the 90 percentiles -- than competitive motors." Because Maxon motors are non-cogging, they provide very smooth movements, again helping the baby T to look as real as possible.
The tight design specifications of the actuators meant that they had to fit a space about the size of the palm of your hand and still offer high-load characteristics, all in a linear movement equal to a full two inches -- the requirements posed by the Stan Winston Studio''s mechanical assembly design. Most devices with a similar stroke would have to be twice as long as the space available inside the baby T-Rex and would have lower load capabilities. "What I needed was an actuator that was smaller, stronger, smoother, and quieter, and Maxon was able to deliver the right motor for that design. Quiet operation is more a concern when I''m working on a live TV show project, or when the animatronics is to be used on-stage or in a museum," Craig explains.
"What I typically need for film animatronics is not only a unique mechanical design, but a motor that reliably handles high loads at short duty cycles," Craig says. As part of Craig''s mechanical design needs, a special, semi-custom motor was supplied by Maxon. He used the company''s 13mm and 16mm RE Series motors with special lubricants, like the low-temp lube used on the Mars Sojourner job Maxon supplied motors to. "I push Maxon Motors above and beyond their operating envelopes. And when I have a problem, the company provides the best in customer support, offering technical solutions for most of my needs."
Maxon furnishes CK Design with a special basket wound motor using a fiberglass-reinforced basket for a variety of special applications. To adjust to the heat dissipation of the motor, Craig now uses a local machine shop to produce a special housing that also functions as a heat sink. "I use Maxon motors because they offer the highest quality product (size and efficiency) in the business. Other manufacturers'' products are unable to compete in many of my applications, some of which must operate at high altitudes or in hostile environments."
For the T-Rex, Craig was able to adjust to the downsized model through some engineering feats not normally encountered. "Sometimes you have to look at the problem from a completely different angle before you can even begin to design." Perhaps it''s the influence of the creative minds in the movie industry and perhaps it''s the influence of the creative minds of designers, but the answers to such challenges seems to occur once the problem is fully understood. I find that Maxon components are more robust than other components I''ve used." Maxon allows us to keep the movements slow and still not get the cogging you get from some motors.