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Revenge of the Mummy

Revenge of the Mummy

Universal Studios' newest attraction, "Revenge of the Mummy-The Ride," is the first dark ride to combine advanced roller coaster technology, animatronics, and special-effects technology into one terror-inducing trip into Ancient Egypt. Join us-if you dare-as we go behind the scenes to find out how engineers created one of the most thrilling amusement park rides of all time, thanks to advanced motion control and propulsion technologies, state-of-the-art animatronics, and a complex control system.

The first thing to understand about the amusement park industry is that it is viciously competitive. A lot of people spend an awful lot of their time trying to come up with ideas for new rides that will blow the competition away.

The challenge, of course, is that there are not all that many ways you can come close to scaring people to death. The Tower of Terror-which creates the unique experience of a seemingly out-of-control plummet down a very long elevator shaft-is still considered to be one of the most novel attractions of all time. Certainly it's one of the most popular. And it's now 10 years old.

From the earliest planning meetings for the Revenge of the Mummy ride, Universal Studios was striving to create a "category buster." But there are limits on the absolute velocity, acceleration, and forces, as well as the number of axes of motion, one can safely subject the human body to. So the designers began to think about taking a completely different approach to creating an unprecedented ride experience: They began thinking about developing a dark ride that would blend elements of Hollywood special effects, animatronics, and advanced ride technology.

The result: The "world's first psychological thrill ride," inspired by Universal Studios' hugely successful Mummy movies. Traveling back in time 4,000 years, it plunges unwitting riders into a harrowing journey through ancient Egypt and a confrontation with an animatronic version of the mummy Imhotep, notorious Keeper of the Dead. Along the way, guests are catapulted into darkness-first shooting 45 ft uphill in 1.5 sec then plunging down below ground level. In all, they will experience seven, near-0G moments, and whiz through several high-speed, 80-degree turns. "The goal of the ride was to make it as fun and thrilling as possible while still maintaining the target family demographic," says Mike Hightower, senior VP and the lead engineer on the project.

The ride, which opened in both Florida and California earlier this year, follows roughly the same story line and features the same ride vehicles in each location. But each ride has a unique track layout to conform to the configuration of the building. In California, the overall height of the building is lower, and the coaster launch begins on a horizontal plane. In Orlando, the project team chose to use an existing building that once housed the King Kong ride. Here, they achieved the height necessary for a vertical launch by digging two pits below the floor.

Imhotep has 34 motions powered by 4,000-psi hydraulics.

Advanced Ride Technology

To propel the multi-ton ride vehicles through an intricate track configuration, engineers incorporated a variety of linear synchronous motors (LIMs) and a new, single-sided linear induction motor (SSLIM) technology. In this type of motor configuration, the motor stator is essentially unrolled to become a linear stator. The SSLIMs are mounted on the track between the rails. The motive force is produced through the magnetic field generated by the SSLIM and an aluminum reaction plate that is part of the center beam of the ride vehicle.

To achieve forward-and-backward motion on the track, engineers used a combination of strategically located LIMs, SSLIMs, and pacer motors. The LIMs are powered from an independent 5,000 kvar transformer and run through a 2,500 kvar adaptive var compensator (AVC).

Controlled by a variable-frequency drive for speed and thrust control (as opposed to operating at a standard 60 Hz), an advantage of the non-contacting SSLIM technology is that it allows propulsion on a curved, horizontal track and offers a wide range of options in terms of velocity control. The SSLIMs can be commanded to thrust in either direction, although reverse thrust is only employed for decelleration. For precise positioning, a servo feedback loop is created by using proximity sensors to observe the position and velocity of the vehicle. The measured data is then compared against the commanded velocity and corrections are made if any discrepancies exist.

"The variable frequency feature on the SSLIM also allowed us to control the vehicles through both the slow-moving themed environment and the high-energy, coaster section of the ride," says Hightower, who adds that one of the most difficult engineering challenges was controlling the vehicles through the more leisurely portion of the ride. Here, the vehicle location must be tightly choreographed with special effects like a ceiling of flame, swarms of scarab beetles, and hologram ghosts created using black lights. And of course as is the case for even for the most elaborate production (according to the New York Times, the two rides cost a reported $80 million), engineers had to wrestle with the inevitable trade-offs. The tighter the motor spacing, for example, the higher the resolution, but the higher the associated cost.

Force feedback compensates for any unplanned shaking of an animatronic. Also known as compliance, it involves locating a load cell between the cylinder body and rod end and producing an analog output that is proportional to the applied load. The signal is analyzed, and any unwanted vibration damped. Some engineers achieve compliance without the use of a load cell, but they must contend with the problem in a moving figure of constantly changing load.

Since engineers couldn't just pack motors in at will (they ended up with 46 total), tuning turned out to be quite a challenge. "We had to tune the system to accommodate a wide range of vehicle weights, which is dependent on guest loading, variable vehicle drag, which is dependent on the amount of side guide-wheel pressure and wear, and the limited ability to thrust/retard the vehicle as it crosses each SSLIM. It was quite a challenge," Hightower explains. In fact, so difficult was fine-tuning that it continued for awhile even after the attraction opened.

Multi-ton vehicles operating on the same track and at high speed must also be capable of stopping reliably, and with its four types of brakes this ride is no exception. For starters, engineers used standard, pinch-style coaster brakes to positively hold the vehicle in a fixed location, such as a turntable. These brakes also function as anti-rollback devices on the launch and for block zone separation.

A common feature on roller coaster rides that run multiple vehicles on the same track, block-zone safety systems keep one vehicle from running into another by sensing their presence and preventing the following train from entering the zone. Platen-style brakes also were used for zone separation in the slow-moving, curved section of the tracks. They press against a plate on the vehicle's underside to bring it to a stop.

Engineers also employed passive magnetic brakes to slow the velocity of a vehicle without stopping it. These noncontacting brakes scrub energy proportional to the vehicle's speed without causing any wear on any surfaces. Active magnetic brakes are used in conjunction with these passive brakes to further retard the vehicle's speed, but not stop it completely. This type of brake is common on heavy vehicles that require additional braking prior to the pinch brakes engaging.

An Animatronics Marvel

A hallmark of the Revenge of the Mummy ride is the close-up encounter with Imhotep, the decomposing mummy intent on causing mayhem. In fact, ride designers wanted this aspect of the ride to be so in-your-face that they initially considered suspending the mummy from a robotic arm, engineering it in such a way that the 6-ft 8-inch rotting mess of rags would leap out and swoop down directly in the ride vehicle's path.

Nope, this isn't the terminator. Before installation, the hydraulically powered animatronic Imhotep is seen without his skins. The multitude of actuators and cylinders that permit the animatronic to make 34 independent moves will be cleverly concealed within the mummy's eviscerated chest cavity, clothed only by a scant amount of rotting rags.

They ultimately didn't pursue that idea, but the animatronic mummy-attached by its torso to a beam connected to a slide mechanism-does jump out in a convincingly real way from a crouching position. The Imhotep figure in Florida has 34 independent motions powered by 4,000-psi hydraulics, with both analog and force feedback control. Engineers say they control leakage in this relatively high-pressure application by using specially designed seals.

In contrast, the figure in California is powered by both analog and digital 80-psi air, at about one-third the cost of hydraulics. In addition to classic motions like a torso twist, five-way head movement, and sweeping arm movements, this Imhotep has an excellent dislocated jaw motion, achieved through asymmetric movement of the upper and lower portions of the jaw.

Common on aircraft control hydraulic systems, force feedback control in animatronic applications employs servo feedback to gather force and position signals, using load cells between the cylinder body and rod end to control any unintended vibrations or shaking. (Engineers call this the "boing-boing" effect.) A particular challenge with force feedback control in a moving figure is compensating for the fact that the angle at which the load is applied is constantly changing, causing a different force component to be transmitted. Engineers did not comment on how they coped with this problem, but the figures seem to be devoid of any shakiness.

Robustness and maintenance were key considerations in the design, since the figures operate some 12 to 16 hrs per day. Engineers say that the design requirements took into account the considerable fatigue associated with the enormous number of stress cycles that typical show equipment is exposed to over its lifetime (some 20 to 30 years!). They also took steps like fabricating most of the linkages out of high-strength, stainless steel, machining them out of solid block with few welds to minimize stress risers.

A Sophisticated Control System

Animatronics: A hallmark of the ride is a close-up encounter with the 6-ft, 8-inch Imhotep mummy.

The ride-show supervisor (RSS) system functions as the overall supervisory control system, tightly choreographing all elements of the show, employing real time data from PLCs, linear logic devices, and sensors. Each of the show elements is controlled by a subsystem controller (SSC), which is sent a start trigger by the RSS to control the overall timing of the show with the ride.

The user interface itself consists of several levels, starting with the main operator interface that features a set of touch screens and hard switches and buttons. Residing in the Technical Director's booth, the station functions as the overriding supervisor for the ride and provides information on the status of the attraction and alarm conditions. Several operator control panels are located throughout the ride for use by technicians to monitor and control various show elements and ride components, such as track switches.

To keep the entire show in sync, motion profiles are updated continuously, allowing the animation to be locked to other show elements. That way, when Imhotep jumps out and shrieks, "Your souls belong to me!" his dislocated jaw moves in perfect unison. And that's pretty scary.

Revenge of the Mummy-The Ride Rock 'n' Roller Coaster
Location Universal Studios - Orlando and California MGM Studios - Orlando
Propulsion Linear synchronous motors Linear induction motors, side linear induction motors, pacer motors
Max G's 1.3G >1G
Noteworthy features of coaster ride Vertical launch (25-degree slope), of backward/forward movement on track, seven near "0G" motions Catapult-style launch and three inversions
Pop culture personality Brendan Fraser of the Mummy movies Steve Tyler of Aerosmith Box title: Two Tales of Terror
Box title: Two Tales of Terror
Web Resources
//Check out Recent Design News Articles on Amusement Park Ride Design//

Former Russian aerospace engineers design roller coasters:
http://rbi.ims.ca/4353-556
The engineering behind Disney's Tower of Terror and efforts to improve ride safety at:
http://rbi.ims.ca/4353-557
Animatronic dinosaurs at Universal Studios' Jurassic Park ride:
http://rbi.ims.ca/4353-558
An inside look at an animatronic Elvis the Pelvis:
http://rbi.ims.ca/4353-559
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