Sport park turf design goes high tech

Baseball park lawns always appear so perfect with their logos and alternating light and dark stripes, determined by the direction the grass blades lay and how they catch and either absorb or reflect the light. And, while it might not be agriculture as we think of it, there might be some lessons to learn from it, now that the boys of summer have hung it up for another season.

Those logos and design patterns must be a big-time headache for a groundskeeper to create and change from one day to the next. And how does he know he got it right unless he hoofs all the way up to the top deck for a better view?

Well, the groundskeeper has a new helper in the form of a self-enclosed GPS-type system that fits within the tall stadium boundaries. It gives him the capability to build designs never before dreamed of in a baseball park.

Traditionally, the solid roller at the back of the riding mower determined the lay of the grass blades, says Adam Thoms, a turf grass specialist at Iowa State University.

“Laying turf grass blades in different directions determines how the light will reflect off it. Turf grass blades laying towards you look dark. Those laying away from you look lighter in color,” Thoms said.

“A solid roller will help bend the grass in broad designs. Brooms can create intricate designs. Blasts of water can lay the grass down for detail. Streams of air can create patterns in both directions at once.

“The mowing pattern of cool-season turf grasses should always be parallel to the lines painted on the field to avoid the lines appearing wavy. Some mowers now have global positioning systems to help create these mowing patterns and to make sure the lines the

New Ground Technology in California’s Silicon Valley is one of the companies developing turf art devices. NGT founder Pete Davis said its main product is called the TurfPrinter because it function like a 3D printer, only on a much larger scale. | Pete Davis photo

y are producing are straight.”

 

New Ground Technology in California’s Silicon Valley is one of the companies developing turf art devices. NGT founder Pete Davis said its main product is called the TurfPrinter because it function like a 3D printer, only on a much larger scale. TurfPrinter is a complex set of software that speaks to a special machine that resembles a riding lawnmower.

“Every blade of turf has a perfect highly reflective quality to it. It’s glassy and shiny. That’s what we work with,” Davis said.

“Our machine organizes every blade of grass in the ballpark. It manipulates the angle of these little reflectors to train the light into the eyes of the fans and television cameras. We manage the entire ballpark lawn in three-inch squares, or pixels. We manipulate every three-inch plot of turf with our enclosed GPS-type system. Each three-inch pixel is either a reflector or a shadow, depending on how the TurfPrinter machine bends the grass.”

Davis said he kept a close eye on developments in agricultural GPS for a long time before he invested time or money in the TurfPrinter idea.

Before 2000, the U.S. federal government had kept a tight hold on the key to accurate GPS positioning. Davis knew his concept wouldn’t work unless he had access to RTK survey-type accuracy. In 2000 those restrictions were lifted for agriculture, and the door opened for his TurfPrinter project.

He said a TurfPrinter operator writes a prescription just like a farmer writes a prescription for variable rate fertilizer in a specific field. In the case of the ballpark device, it’s called an artwork prescription, which is translated into machine codes.

“The way we’ve designed the architecture of the machine, the operator simply rastor drives or just drives up and down the field,” he said.

“He doesn’t even know what he’s printing.”

NGT started with GPS for TurfPrinter control, but tall stadium walls surrounding typical baseball parks prevented it from achieving the level of accuracy it needed. The problem was worse when working with European clients because their soccer stadiums are basically enclosed with a small hole in the centre of the roof.

Davis switched from GPS to a self-contained laser guidance system called Total Station with the laser on a tripod transmitting position information to the machine.

“This is kind of unique because there’s only one tower,” he said.

“There’s just one laser robot, a single tripod, and it rotates. It uses the angle between the tripod and the machine on the turf, along with the time of flight of the beam between the tripod and the machine. That’s how it calculates the X, Y and Z. This happens at a very high rate of speed with accuracy of less than one centimetre.

“So we don’t use satellites at all. It’s called a local positioning system, as opposed to a global positioning system. It’s the type of local positioning system used in the construction industry.”

Davis said each three-inch pixel continuously reports to the laser robot for instructions on which way to bend the blades of grass within the square. The robot receives instructions from the art file, which is built by the NGT artist or programmer. The manager of the ballpark tells NGT what grass graphics he wants that day and the artist creates the art file.

“When the TurfPrinter is told to make a dark square, a small gate opens up and a high-speed blast of air lays the blades of grass in that specific three-inch square down in the appropriate direction,” he said.

“The jet of air is Mach 0.5, which is over 300 m.p.h. And it’s thin. It’s just one millimetre. That’s how we can achieve such accuracy in the final rendition. That also means the TurfPrinter machine can travel along at a pretty good clip and still paint an accurate picture on the grass.”

NGT currently manages the turf art in three major league ballparks. It and other similar systems work well only with cool season grasses, which limits their geographical market. Davis said these cool season grasses don’t work well in the hotter southern states.

Davis says the biggest item on his life’s bucket list is to create a new Guinness World Record turfgrass message that will be visible to the folks in the International Space Station. He says he’s “open to offers from Monsanto or John Deere to get that done.”

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