The Tech in the Toys

Here is an article from the Design News covering some of the technical aspects of Toy Story Midway Mania, it may be a little too technical at times, but it is certainly interesting. Here it is:

Old-school midway games just got a high-tech makeover from Walt Disney’s Imagineers. Their new Toy Story Midway Mania attraction, which opened in Disney’s California Adventure Park earlier this week and in Disney World in May, recreates the kind of shooting and throwing games that can still win you a stuffed animal at carnivals and boardwalks around the country.

These games, however, take place not in carnival booths but in a 3-D gaming environment designed by Walt Disney Imagineers with some help from Pixar Automation Studios. In Midway Mania, there are no physical objects to hurl or fire at targets – no rings to toss, no darts to throw, no air rifles to point at sheet-metal ducks.

Instead, players first make their way past an animatronic Mr. Potato Head carnival barker, whose voice and schtick come from Don Rickles. Then they don a set of 3-D glasses and hop into swiveling ride vehicles that convey them to a series of virtual games. Not counting a practice pie-throwing round, Midway Mania has five scored games in all, each inspired by a different “Toy Story” character.

Once parked in front of the individual games, the players use a pull-string shooter to fire virtual projectiles at a large screen. The attraction tallies scores for all the players based on the point value of the targets they’ve hit. It even awards virtual plush toys, displaying them on each vehicle’s on-board computer screen.

Though the games play out in 3D, the Imagineers have added another dimension to the game. The attraction also includes special effects in which game actions have real-world consequences. Throw a virtual dart that pops a virtual balloon, for example, and you get a puff of air or spritz of water in the face. Chrissie Allen, senior producer and director for the attraction, says the effects add a fourth dimension to the ride. “The world of the game completely envelops you,” she says.

All of that immersive gaming may be a blast, sometimes literally. Yet Midway Mania has a serious side that makes all the fun and games possible. According to Jody Gerstner, Walt Disney Imagineering’s executive director of show and ride controls, the attraction runs on one of Disney’s most advanced automation systems to date. Built primarily around components from one of its corporate partners, Siemens Energy & Automation, the system marks the first time Disney has used industrial Ethernet in a ride control application. “We’ve done show controls over Ethernet before, but those don’t involve moving people around,” Gerstner says.

The automation system breaks new ground in other ways too. One is its scale. “It’s the biggest system we’ve done, not geographically but in the number of control zones,” says Gerstner. Another is in the amount of integration work that had to be done to weave the attraction’s distinct game, ride and show elements into a seamless user experience. And the attraction is a great example of how the clever use of position sensors and software can take up the some of the mechanical slack in motion control systems.

Talk to Imagineers like Gerstner or Allen, and you will quickly get that they obsess about the entertainment value of the rides they create. And in that sense, Imagineering couldn’t be more different than the engineering practiced by those who work on industrial machines. After all, when is the last time anyone had to design a fun form fill and seal machine?

Like all engineers, though, the Imagineers still have to hit hard engineering targets related to safety, throughput, uptime and installation cost. And hitting all those targets in this case called for a control technologies that should appeal to those who design machines for factories rather than theme parks.

Fun with Ethernet

Midway Mania’s overarching control system actually consists of three sub-systems, one each for the ride vehicles, the games, and show elements. Ethernet is the common thread tying everything together.

The ride controls, which govern the movement of the vehicles through the attraction, run on two kinds of industrial controllers. The central wayside controller, a Siemens 319 PLC, manages the vehicle flow through the attraction. “The wayside controller is the traffic cop,” Gerstner says. Each vehicle also has an onboard controller, a Siemens 315 PLC that handles programmed speed profiles, position data gathered from sensors, safety measures and diagnostics.

For vehicles to move through the attraction, the vehicle’s onboard controllers wirelessly communicate their position data over ProfiNet RT to the wayside controller. That central controller then generates a signal, which goes out over a proprietary, hardwired network to the 397 busbar zones on the vehicle steel track. That signal is then transmitted back to the individual ride vehicles through a brush shoe that contacts the busbar Gerstner calls this control out a “go, no-go PWM signal.” It tells individual vehicles whether they have permission to proceed at their programmed speed, whether they should stop or whether they should proceed at a reduced speed.

The game controls likewise have both centralized and onboard elements. A centralized PC-based gaming controller distributes gaming data from each ride vehicle to a bank of computers that run all the gaming software. The massive computer farm for Midway Mania houses more than 150 computers in all, including one Windows XP PC from HP for each of the attraction’s 56 game screens. The on-vehicle controllers handle game information specific to each vehicle, such as the positioning of the shooter and onboard score display.

As with the ride controls, the centralized and on-board gaming systems communicate over wireless Ethernet, sharing the onboard wireless infrastructure with the ride controls. Physical connections between the game computers take place over a standard 100 Mbit/s Ethernet network – with the exception of a gigabit backplane between the switches in the main game controller.

Both the ride and game control systems share a wireless link to get data off the vehicles. On the vehicle is shared Siemens SCALENCE W access point module on the vehicle which couples with SCALENCE W access points off the vehicle via a leaky coax cable along the track. Olaf Scheel, a Siemens engineer who served on Midway Mania’s design team, the wireless system has been “hardened” to prevent any intrusions or denial of service attacks. And he notes that on the ride control system, safety is ensured by the one-way nature of wireless communication. “The onboard controllers only send data,” he says. They get their go-signal only through the hardwiring.

Aside from the ride and game controls, the system has additional PCs for its show controls, including a rack of computers that run the attraction’s special effects. These, too, are nodes on the standard Ethernet network.

Working Together

Taken individually, Midway Mania’s individual control systems are pretty straightforward, but it’s how they work together is what determines whether attraction soars or falls flat. “The hardest part of the project was defining all the software interfaces between the game, ride and show controls,” Gerstner says, noting that all three systems have to be closely coordinated to deliver that seamless user experience.

The game and ride control systems, for example, both coordinate their efforts at all times. During normal operations, the game controller needs to know where the ride controls have parked vehicles relative to the game screens. That task is trickier than it sounds. Gerstner says the electric motors, right-angle gearboxes and pinch-rollers that move the vehicle have a certain amount of play in them. So do the mechanical brakes that stop the vehicles in front of the screens. “We had to find a way to compensate for the variation inherent in our mechanical system,” he says.

The game and ride controls also mount a coordinated response to back-ups or delays, which could be caused by someone triggering one of the attraction’s many pressure-based safety devices or even a slowdown in the vehicle loading process. “We know back-ups happen,” Gerstner says, “but system does the right things even when everything isn’t perfect.” Those right things include launching game sequences, such as an extra practice round if users get stuck in front of one screen for too long. They also include more theatrical responses, such as an announcement voiced by “Toy Story” characters.

Many of these coordinated efforts require the ride and game controls to use position data gathered by two complementary tracking methods. The first uses Pepperl+ Fuchs binary proximity sensors, four of which are mounted beneath each ride vehicle, to pick up a set of absolute position markers scattered at strategic locations along the track. “These give us an indication of where each vehicle is in the building,” Gerstner says.

While crucial for generating the go-no go signals and controlling the flow of multiple vehicles, proximity sensor tracking lacked the resolution needed to register the vehicle to the game screen. So the Imagineers added a second tracking system that can determine vehicle position within an inch. It uses a Banner laser sensor, again under-mounted on the vehicle, to read graduated strips placed in the floor near the parking locations for each game. This fine-positioning system helps compensates for all the variation inherent in the mechanical system. “The game doesn’t care if the car parks in the same spot every time. It just needs to know where each car has actually parked, and it can compensate.” Gerstner says.

Positioning data also plays a key role in determining the position of the shooter relative to the game. An algorithm in the game software determines position using data from the three encoders on the shooter itself along with another encoder that measures the amount of swivel on the ride vehicle turrets. “Turret swivel is superimposed on the rotational axis of the shooter,” Gerstner says. The shooter-position algorithm also takes the vehicle’s actual parking position into account. Gerstner describes this positioning algorithm “very complex,” but adds that it still made more sense than trying to come up with a separate sensing system. “We had enough accuracy to mathematically determine the position of the shooter tip with data we already had,” he says.

A New Approach

Midway Mania’s controls embody a couple of important departures from Disney’s traditional way of engineering large control systems. Gerstner points out that the company’s larger attractions tended to have point-to-point I/O in the past. That design approach can be clearly seen in square footage set aside for I/O cabinets in a room adjacent to Midway Mania’s massive computer farm.

Much of that control room remains empty, however, since the ride controls take up just two cabinets. Gerstner attributes much of the control system’s physical economy to the Siemens’ distributed I/O and to the Ethernet backbone that ties all the control systems together. “Ethernet simplified the wiring and all the associated touch labor,” he says. “To be honest, I don’t know if we could have done this project using our traditional architecture. It would have taken a lot of copper.”

Another departure for Disney is in its use of a centralized controller in an attraction of this scale. In previous rides with a similar zoned busbars – such as its Rocket Rod ride – Disney had to distribute the controllers around the rides. “We couldn’t go centralized because of the challenge of processing and send permissible signal out to all the zones,” Gerstner says. The 319 had speed and power to overcome that problem. “It’s a screamer,” Gerstner says.

In fact, central PLC and the ProfiNet RT had more than enough processing muscle and speed for this application. Scheel notes that the central PLC scans and execute the code for all 397 busbar zones in 32 milliseconds. “We could go faster if we had to, but there was no need,” he says, noting that ProfiNet RT can update every millisecond if necessary.

Same goes for PCs and Ethernet used in the gaming systems. Gerstner says it has bandwidth to spare, and its switches only utilize about 10 percent of their capacity at any given time. “That’s the thing about bandwidth, you never know how much you’ll need when you start a project. So it’s always better to have more than less,” he says.

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