Virtual Monster

Lakewood, NJ--When it comes to thrill rides, fun may be the most important thing, but it's not the only thing. Just ask Frank McClintic, whose company Max-Flight Corp. makes rides that combine a virtual reality display with a full-motion platform capable of 360-degree, two-axis movement for a true "what you view is what you do" experience. MaxFlight has always engineered its virtual reality rides for fun, but McClintic recently decided that the company should re-engineer them to improve their reliability out in the field. "We were looking to make the rides maintenance free," he says. His solution: "Get rid of the hydraulics and go electric."

The first ride to make the switch to electric motion control is a brand new monster truck simulator called "MaxZilla." Depending on a particular rider's skills and aggressive tendencies, the MaxZilla experience can range from a bumpy jaunt along a virtual track to a stomach-churning spree punctuated by flips and rolls off embankments and other obstacles.

Though some riders may be more concerned about retaining their lunch than the motion control technology creating the thrills, the switch to electric components required sweeping changes to the MaxFlight's motion base--which all its rides share. "From a design standpoint, there's not one component in the system that we didn't have to change," say McClintic, noting that the whole redesign took about eight months.

Perhaps the biggest challenge was finding the right motors and drives to move the cab, which weighs up to 2,000 lbs with the riders inside and scribes a 10-foot circle as it swings around the motion base. Describing the ride as a "high-inertia system," McClintic notes that "the torque can get pretty high." On the pitch axis, the unit needs about 600 ft-lb of torque while deceleration requires double that amount. "It has to stop instantaneously," McClintic notes. The roll axis, meanwhile, needs half the torque required by the pitch axis.

To meet these requirements, MaxFlight selected ac drives from Mitsubishi Electric Automation (Vernon Hills, IL) and right-angle gear motors from Sumitomo Machinery Corp. (Chesapeake, VA). On the pitch axis, MaxFlight uses a 103:1, 5-hp motor, while a 73:1, 3-hp motor powers the roll axis. The motors feature a hollow-bore shaft, which allows MaxFlight to pass through the various electrical signals for video, audio, and motion control--about 34 signals in all. The motors on both axes have a built-in brake, important for the safety-conscious amusement business.

To lift the cab 30 inches into riding position, MaxFlight selected actuators from Nook Industries Inc. (Cleveland, OH) that combine a ball screw and worm gear. "It was one of the few actuators that met our requirements," says McClintic, explaining that MaxFlight wanted to use a single Baldor Electric Co. (Ft. Smith, AR) motor to drive the actuators on opposing sides of the ride.

Other updated components on MaxZilla include a set of slip-rings from Litton (Blacksburg, VA), which translate the fixed electrical connections into rotating motion. According to McClintic, the moving surfaces of the new slip rings come together in a "brush-like" interface rather than the spring-loaded, metal-on-metal contact of previous slip rings. He expects that change to drastically reduce maintenance requirements.

"The old slip rings had to be maintained every seven to thirty days by a technician trained in our factory," he says, adding that the new ones don't need any regular maintenance. What's more, the Litton rings offer a USB interface, which supports MaxFlight's ongoing migration away from the lower bandwidths of RS 485 and RS 232 communications or the PC-based motion control system.

Finally, MaxFlight added a new electric actuator from Motion Systems Corp. (Eatontown, NJ). Located behind the cab, it moves the automatic counterweight system that balances the loaded cab.

McClintic expects the move to all-electric to pay off for his customers, including operators of malls, amusement parks, and casinos: There's the reduced maintenance on the slip rings and what he considers a relatively long life and low replacement cost for electric components in general. "You can go 15 years before an electric drive quits," McClintic says, estimating that the added reliability will save the typical customer, "several thousand dollars per year." What's more, the all-electric rides run on both single- or three-phase power, saving about $4,000 in installation costs at sites that lack three-phase power, such as shopping malls.

While MaxZilla represents the first all-electric model, all the company's other rides share the same motion platform and will follow suit. These include the company's flight, roller coaster, and bobsled simulators. And this update motion platform may soon drive other virtual experiences as well. "Now that we don't have to worry about motion anymore," says McClintic, "we can focus on creating new worlds."