Roller coasters go robotic

Associate Editor

Imagine shooting it out with bug-eyed monsters while pulling 2 g, and — just to make it interesting — flailing about like a straw in the wind. Sound like fun? Well, thanks to advances in robotics, you might be doing just that on your next visit to an amusement park.

Several companies are leveraging robotic technologies into passenger-carrying robotic rides with names like "RoboCoaster" and "Fight or Flight." Kuka Robotics has joined Amec, a projectmanagement and services company headquartered in London, and Primal Rides, Ont., Canada, an entertainment and attraction manufacturer, to create rides that are part flight simulator, part roller coaster, and part interactive game.

FROM HOISTING ENGINES TO LIFTING SPIRITS
The technology to produce economical, reliable, and, most importantly, safe, passenger-carrying robots proceeded from the auto industry's widespread use of robotics.

About five years ago, Kuka Roboter GmbH — a leading robot manufacturer in Germany and Kuka Robotics' parent company — stopped making the KR500, its well-known 2.6-ton, 500-kg-pay-load robot. The six-axis mechanical arm, a production superstar, had set new standards for safety and reliability installing thousands of engine blocks. But Kuka needed new markets and the amusement industry looked like a good bet.

Kuka wanted the robot to take on a new role: Giving human passengers the ride of their lives. Rather than merely move people along a track, Kuka wanted to move riders anywhere within a hemisphere.

The idea: Put people inside robots with enough stroke and movement for smooth, precise acceleration.

Gino De-Gol, president of RoboCoaster Inc. and the ride's inventor, got the idea for turning the robots into amusement-park attractions over a decade ago while installing the machines at a Rolls-Royce factory. Then, the robots couldn't carry the weight of several people. But radical improvements in gearboxes and power amplifiers, plus the switch from proprietary to open operating systems gave the machines enough muscle and flexibility to handle the task.

Still, adapting the KR500 for passenger-carrying certification was an expensive, painstaking task. The effort required new casting patterns and a new casting process. Passenger-carrying robots are vastly different from their industrial counterparts, going through much more-stringent specifications and manufacturing processes. "These robots are overengineered for passenger safety," says Christon Manzella, Kuka's key technology manager.

The result was RoboCoaster, the first licensed passenger-carrying industrial robot. Each vehicle is a chassis-mounted robotic ride platform that moves in ways not possible with traditional linked cars.

RoboCoaster takes a six-axis motion base and adds it to another ride. Conventional motion bases are almost entirely limited to movement within their own footprint and normally don't have full 360° pitch, yaw, and roll. Robot-derived rides, however, not only give the six degrees of movement, they operate in the movement envelope of a typical revolute articulated arm. This allows passengers to experience gs much longer than is possible with conventional hexapod arrangements.

On a roller coaster, passengers look straight ahead, bracing for anticipated turns and dips. But RoboCoaster riders can't anticipate. Four passengers, strapped to the end of a 16-ft robotic arm, move in a nearly limitless ride profile at 2 g while participating in an interactive shooting game. As riders succeed in hitting targets, the intensity and speed of the robot climb.

The robot throws riders in any number of directions and makes them swoop as if they were in a jet fighter. Optical sensors attached to a motor in each axis calculate the position of the coaster's arm every 32 msec. Despite the commotion, Kuka says it has had no problems with Robo-Coaster riders becoming injured or ill.

After debuting RoboCoaster in 2002, Kuka sold 10 of the rides to Legoland Denmark. RoboCoaster was turning family entertainment on its head — not to mention opening a new revenue stream for the tried-and-true robots. To date, about 60 Kuka Robots (with another 15 on order) have been delivered to the amusement-park industry.

ROBOCOASTER GEARS UP
Kuka worked with Amec's Dynamic Structures group to develop and market the second-generation RoboCoaster for large theme parks, which have a much greater throughput (500 to 1,500 rides/hr) than the smaller family-entertainment centers (FECs). (To determine the number of robots necessary to handle the volume, desired capacity is divided by the time-cycle of the ride profile.)

To boost passenger throughput, Kuka removed the KR500's fifth and sixth axes, brought the center of gravity closer to zero origin, and brought the movement closer to the center. The payload of the new KR500PUV went from 500 to 800 kg, so each robot (car) could now carry four riders. RoboCoaster operates 18, 20, or even 30 robots on advanced roller coaster track, accommodating up to 2,000 riders an hour.

Amec supplies the track and the hardware that integrates the robot and the track. In other words, Kuka provides robots and controls, and Amec supplies everything else.

"RoboCoaster can simulate a lot of other rides. It has the dynamics, movements, and sensations that you get from coasters, from LIM (linear-induction-motor) launching systems, or from ejector-seat-type rides," says De-Gol. The system lets the operator choose from an almost infinite variety of combinations.

"Standard FEC systems have five variations: gentle, fast, fun, turbo, and extreme" says De-Gol. "'Extreme' is limited by the amount of force ( 1.9 g) mandated by law, and gentle is almost relaxing."

The force created by the robots is no greater than that of conventional roller coasters. Riders experience no more than 2 g, moving at a top speed of 12 fps on long-stroke versions of the ride. The track can be floor mounted or overhead mounted, depending on budget and the ride's creative intent. The current standard is floor mounting, either directly to the floor or on a linear track. The track's steel backbone is fabricated with the aid of CNC equipment. Vehicle guide rails, mounted on arms attached to the backbone, create a quiet, smooth running surface.

RoboCoaster pushes the rollercoaster envelope by (literally) throwing people around, turning them upside down, putting them through loops, and subjecting them to as much force as the law allows.

Usually, RoboCoaster is installed indoors to enhance visual impact and interactivity. The ride's movement cycle can be structured to suit the spatial requirements of the building. A footprint of some 12 11 m with 7 m of headroom is necessary for full and unrestricted motion. A typical ride lasts between 2.5 and 4 min.

GETTING THE "JERK" OUT
To create the illusion of reality, Amec had to synchronize the motive and visual aspects of the ride. The ride had to be smooth and silent, perfectly synchronizing what riders see and feel. The key to obtaining a high level of smoothness is getting rid of "jerk" — technically speaking, abrupt acceleration change. Removing jerk lets the operator put more load on the passenger's body.

Older roller coasters have guide-rail pipes that connect to large so-called backbone pipes. The car wheels run on these guide rails.

It was difficult to define the geometry of these old-style coasters. Shape and smoothness of the track, friction of the wheels, and speed were all factors. Plus, there was the problem of banking the turns to properly equalize forces. These same roller coasters disintegrate from fatigue. Every year, casters on the old-fashioned roller coasters must be replaced. Tracks must be inspected for wear and tear. "But with robots, you're looking at 20,000 hr before the first oil change," says Manzella. "In this industry, that's about five years." Statistically, he says, no robotic component will fail before 70,000 hr (about 15-years service).

Before CAD modeling, experience was the best teacher. Now, designers better understand how the cars move and can better control g forces. Computers accurately balance spinal and radial loads. And track specifications are within 1/8 in. (about 4 mm) over 40 ft.

Kuka's robots proved themselves by years of building cars. This time, they are proving themselves by carrying passengers willing to pay for the thrill.

The technology is safe. Seamless visual and motion experiences, lifelike images, and interactivity-merge to create a new reality. Rollercoaster design has grown from an art to a science.

Typical FEC systems have additional peripheral or interactive equipment such as infrared guns mounted on the gondola and passive infrared sensors on targets scattered around the movement envelope. In water parks, people on the ground as well as those on the ride can be armed with water cannons. RoboCoaster offers the thrill of larger rides in a much smaller footprint, and at a lower cost (about $300,000/robot).

"FIGHT OR FLIGHT"
Another partner, Primal Rides, plans to use Kuka's robots for its new themed FECs. The company's "Fight or Flight" ride will launch riders into alien worlds where they can choose between fighting aliens with laser-tag guns and simply enjoying the flight. "Fight or Flight" promises to bring the excitement of much bigger parks to the smaller local venues.

Sure, some kids, old and young, will continue their love affair with the old-fashioned, bone-jarring roller coasters. But several major theme parks and local family-entertainment centers are climbing aboard robot-controlled thrill rides just in case.