Orlando, FL —In the movie version of Jurassic Park, things go horribly awry because the scientists who cloned the dinosaurs could not control them. At Universal Studios' theme park version of the popular dinosaur flick, bedlam also breaks loose. But only where intentionally planned by the engineers who designed and control the 15 animatronic dinosaurs that populate the Jurassic Park River Adventure Ride. They also worked their magic on the Triceratops Encounter, a decidedly more serene experience.
Adding to the thrill factor is the fact that the dinosaurs look and move in ways that are almost as convincing as their movie counterparts—a tribute to the painstaking efforts of design engineers to achieve a high degree of dino-realism. Hydraulics engineer Brian Poole credits the use of innovative hydraulics, motion control technologies, and materials for the park's success.
"Typically, if an engineer is designing something like a bottling machine, all he or she really cares about is the end result. The engineer knows something must move from point A to point B, but really doesn't care what happens between the two points," explains Poole. "When it comes to animation, however, every point along the way counts. If a figure looks jerky and its movements are not natural looking, the whole effect is lost. Technology helped us overcome that."
Taming the wild beast. In order to reproduce the motions of actual dinosaurs, engineers at Universal Studios first consulted with scientists who study the skeletal remains and biomechanics of the prehistoric creatures. Wherever possible, they chose hydraulics to power those movements, not only because of the high masses involved (the head, neck, and hip joint of the tyrannosaurus rex weigh 10,000 lbs), but also because of the accuracy and simplicity of operation.
The quality of animation in the Triceratops Encounter was critical, given the fact that visitors are able to get up close to the dinosaur and spend many minutes viewing it. To determine the triceratops' exact type and range of motion, engineers consulted with scientists who study the biomechanics of dinosaurs. The triceratops (shown here in skeletal view) has 28 axes of motion, all interrelated via load paths through the four legs. Key to the naturalness of the dinosaur's motions was the use of servohydraulics and the design of the underlying skeleton. Based on fossil records, the skeletoncontains the various linkages and support points necessary to produce the required motions. Some are extremely complex, such as the ankle, which features three degrees of motion and resembles a gimbal in design.
"Hydraulics give us a quality of motion that we are very comfortable with," says Steve Blum, director of engineering for the Islands of Adventure project. "Digital motion, on the other hand, tends to have an error band in the velocity-profile has a net error in the tracking that causes the motion to be less accurate. Mixing pneumatic, hydraulic, and electronic technologies also makes the maintenance issue a bit more challenging."
In order to make an ultrasaurus' head bob or a triceratops' chest heave a tad more like the real thing, engineers employed closed-loop servo control almost exclusively. "We operate close to 99% of the dinosaurs' functions—which range from the blinking of an eye to a vertical rise of some 120 inches at a peak velocity of 7 ft/sec—in a closed loop fashion," says Poole. "The system uses position feedback to determine whether the actuators are where they are supposed to be, and then makes the appropriate corrections if necessary."
As unsuspecting visitors travel by boat through the lagoon on the River Adventure Ride, the parasaurolophus' odd-shaped head suddenly pierces the surface of the water. While the velocity profile is a simple trapezoid, teh fact that the dinosaur travels 120 vertical inches in just a little over 2 seconds (peak velocity of 7 ft/sec) is remarkable considering that all but the last 36 inches of motion occurs underwater. "That's a pretty good clip to be traveling in water, given the higher drag coefficient," says Hydraulic Engineer Brian Poole. Hidden underwater is a massive, 25-ft-tall structure that supports the dinosaur's 750-lb head and neck.
To eliminate any unintended shaking—always a problem for animatronics with high masses and quick movements—engineers also employed force feedback. Also known as hydraulic compliance, it involves placing a specialized strain gauge called a load cell between each cylinder body and rod end and producing an analog output that is proportional to the applied load. This signal is then analyzed, and any vibration damped, if necessary. Without force feedback? "You would see the stepping motion, for example, of the T-rex as it bends at the waist and leans forward toward the boat," says Poole.
Furthermore, engineers wrote software to ensure that no piston ever reaches the end of its stroke. Typically, the pistons travel between 5 and 95% of full stroke. "Basically, when you go full stroke, you have instant deceleration, which will interrupt a fluid movement," explains Poole.
The use of 12-bit resolution data also helps to avoid any "steppy" motion—a problem 8-bit system users of the past had in trying to manage larger motions with high gains. "Early in the animated figure history, memory, computers and digital-to-analog conversion hardware were very expensive," says Chris Kustura, manager of electrical control systems. "Most systems were based on the 8-bit standard and had to use some form of data compression to store the tremendous amount of information for a complex show. Today, memory is relatively cheap and the cost differential between 8-bit and 12-bit hardware is negligible. Yet the benefits are great."
To keep the entire show in sync—so for example the head of the parasaurolophus pops above the lagoon water just as visitors pass by in a boat—motion profiles are updated 30 times per second. This update rate allows the animation to be locked to video or audio sources that use a recording industry standard of 30 frames per second as the time reference.
Hydraulic enhancements. Several features of the hydraulic power system helped to enhance the dinosaurs' performance, including the use of Vickers' Integral Motor Pumps (IMP) from Eaton Hydraulics (see sidebar next page). Given that the motor of the IMP is completely enclosed in a sound reduction shroud, engineers were able to locate the quiet-running units in the center of the ride building without fear of guests hearing any "out of character" noise. Noise-attenuating baffles also aid in eliminating any fluid-borne sounds.
Fluid cleanliness was a major issue, particularly since most of the installation is located outdoors in sand, dirt, or water, or inside of a building sprayed with fiberglass fire retardant. Moreover, fluid power experts say that 75 to 80% of all system failures are due to contamination of one sort or another.
"The consequences of dirty oil is a degradation in system performance," says Poole. "First, we'll start to notice erratic behavior of servo valves. If left unchecked, the problem will propagate into shafts and seals, resulting in leakage. If we can keep the fluid clean, we can extend the life of the system significantly. That's critical, given an anticipated life of 20 to 25 years for complex animation like this."
Just as a precautionary measure, engineers used SAE flange connections and O-ring ports on the dinosaur modules themselves to help prevent leakage. And to keep things clean, engineers at Simulation Technologies, Inc., who designed the system incorporated four levels of filtration into the design. "For example, we have a very large bank of return line filters that filter 100% of the return oil from the system. There is a separate kidney loop with a completely independent motor, pump, and filter that run continuously whether or not the system is operating, which scrubs the oil clean down to 3 microns. Also, pressure filters were placed directly on the dinosaur accessory manifolds located prior to each piece of animation," says Mike von Hoene, vice president of engineering at Simulation Technologies. To combat the notoriously humid Floridian climate, engineers also installed a device called a Watergate breather from Eaton Hydraulics. It blocks not only particles, but also damaging water vapor from entering the system.
Beauty more than skin deep. The prevailing theory today is that dinosaur skin resembled that of an elephant or rhinoceros. But coming up with a material that would hold up under repeated cycles and, in the case of the triceratops close scrutiny, was no small task.
"What we need is a material that has an extreme resistance to fatigue failure," says Blum. "These figures undergo millions of cycles per year, and their skin must be capable of sustaining substantial strain without sagging or failing."
The skins of the dinosaurs in Jurassic Park are made out of a wide array of silicones, favored for their ability to provide a tough, yet flexible, and easily repairable skin. "We've used silicones with a range of cured physical properties, with tensile strengths ranging from 435 to 600 psi, elongation (%) ranging from 500 to 730, and tear strengths ranging from 110 to 140 ppi," says Dale Chirico, manager of operations support. The specific formulation chosen depends on the animation's particular range of movement and the en- vironment in which it will operate.
The base component of the silicone is pigmented to closely match the dinosaur's dominant color. "And since the pigments themselves are silicone based, they actually become part of the skin itself. UV inhibitors can also be added to prolong skin life if necessary," says Chirico.
Fastening devices are another key consideration in skin design, since exposed zippers, Velcro, or snaps would completely ruin the illusion. In the Triceratops Encounter, where visitors can actually touch the dinosaur, engineers had to figure out how to attach as many as 12 individual skins to the frame without so much as a snap exposed. Double-butted seams at strategic locations did the trick.
The neck skin of the tyrannosaurus rex posed a different challenge: Located in near-darkness, hiding fasteners wasn't the challenge, but rather coming up with a material that would not restrict movement (the head bobs menacingly above the ride track) and was durable at the same time. Engineers finally hit upon a stretchable nylon that is fitted tube-like over the dinosaur's neck and then painted to match the rest of the character.
"Each dinosaur presented its own unique set of technical challenges," says Poole. "But then nobody ever said it would be easy to bring them back from extinction."
Visitors can experience the animatronic dinosaurs in action at Universal Studios' Islands of Adventure theme park in Orlando, FL, seven days week, 365 days a year. For information, go to www.universalstudios.com .
&HEADLINE>Major engineering challenges&/HEADLINE>
Tyrannosaurus Rex (River Adventure Ride)
Support and move a 10,000-lb mass 15 ft in 3.5 sec. Required a separate superstructure within main building in which the dinosaur is suspended 30 ft above the ride track.
Parasaurolophus (River Adventure Ride)
Make large moves very quickly (84 vertical inches in less than 2 sec with peak velocity of 7 ft/sec). The speed is remarkable considering that 70% of the motion occurs underwater.
Triceratops (Triceratops Encounter)
The dinosaur's 28 axes of motion range from subtle movements such as pupil dilation to gross motions of the limbs. The fact that visitors have an intimate, up-close encounter with the dinosaur required special attention to the quality and realism of the dinosaur's motions and skin material.
Ultrasaurus (River Adventure Ride)
The dinosaur has a spine consisting of 9 cascading joints and is close to the ride track, requiring extra large safety factors. Maximum stroke length is 10 inches. Cylinders designed in parallel provide necessary redundancy.
&HEADLINE>Hydraulics almost whisper quiet&/HEADLINE>
Despite the loud, intermittent roars, hooting cries, and snorts of dinosaurs at Jurassic Park, engineers were concerned about the noise levels of the high-pressure (3,000 psi) hydraulic units powering them.
"Any noise relating to the power source obviously impacts the illusion that we're trying to create," says Hydraulics Engineer Brian Poole.
Vickers' quiet-running, oil-cooled Integrated Motor Pump and some cleaver engineering makes sure that the noise generated by the hydraulic power source does not interfere with the illusion of live dinosaurs at Jurassic Park.
Recognizing that the motor and cooling fan are typically the primary sources of noise in a pump assembly, Universal Studios engineers opted for the Vickers Integrated Motor Pump (IMP) from Eaton Hydraulics. By using hydraulic oil instead of air to cool the motor, IMP designers were able to completely shroud the motor in a special sound reduction housing without having to worry about restricting the airflow. Moreover, since the motor is completely immersed in an oil bath—the oil actually flows through the coil—the IMP runs significantly cooler than a conventional, air-cooled motor, leading to longer operating life. That's important in an application like this one, which operates continuously 12 hours a day, 7 days a week 365 days a year. It also means a smaller overall footprint, since components from motors with a lower rated horsepower can be used in the IMP.
Because fluid-borne noise can also be problematic, engineers installed an in-line device called the Suppressor (Wilkes & McLean). Functioning much like a muffler on an automobile, it employs a series of noise attenuation baffles to eliminate any fluid-borne resonance. Also helping to achieve quiet operations was the attention paid to line sizes, says Engineering VP Mike von Hoene, whose company, Simulation Technologies Inc., (Durham, NC), prepared the technical specs, designed, and installed the hydraulic power units (HPUs) for Universal Studios. "We sized every pipe segment in a total of 1.5 miles of piping to limit flow velocities to 10 ft/sec in the return lines and 15 ft/sec in the pressure lines," he says. "In several places, this required 4-inch high pressure lines and 6-inch return lines. That helped to reduce the kinetic energy changes of the hydraulic fluids, thereby ensuring quiet operation."
The upshot? A substantial decrease in noise output. "We're averaging in the range of 75 decibels in the pump room and below 52 decibels in the exhibit area, as compared to somewhere in excess of 100 decibels for a comparable air-cooled system running at 3,000 psi," says von Hoene.
Introduced in 1994, the IMP has gained widespread use in the entertainment industry and other applications where noise and maintenance are major concern. The installation at Islands of Adventure, which consists of 3 hydraulic power units and 21 IMPs located 85 ft above the lagoon inhabited by the dinosaurs, is among the largest to date.