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Penetrating New Ground PUBLIC ACCESS

A Design House Adapts a Radar Device in Search of a Wider Market.

[+] Author Notes

Jack Thornton is a freelance technical writer based in Santa Fe, N.M.

Mechanical Engineering 121(05), 70-71 (May 01, 1999) (2 pages) doi:10.1115/1.1999-MAY-6

Abstract

Sensors & Software Inc. (S&S) is adapting its original line of ground penetrating radars (GPR), which is meant for deep soundings and reconnaissance in rough terrain as well as shallow-depth, high-resolution imaging systems for utilities, roads, and bridges. S&S wanted a molded plastic housing, preferably a high-density polyethylene for high durability. Plastics permit molding complex parts in quantities small or large, as needed. Plastics also allow for curved, ergonomic, and visually appealing shapes nearly impossible to match in machined metal. The big learning experience for S&S was in replacing the machined steel housings for the electronic components, sort of a housing within a housing. Ove Industrial Design simplified the packaging of a ground penetrating radar system, to create a lower-priced version of the product for its manufacturer. Ove used mechanical computer-aided design/computer-aided manufacturing packages called PowerSHAPE and DUCTS from Delcam International Inc. of Windsor, Ontario, which presented S&S with a new experience.

Article

For many years sensors & Software Inc. has designed, manufactured, and sold ground penetrating radars in Canada, the United States, and elsewhere. But the high price and complexity of the instruments limited sales to a few sophisticated users, such as scientific and government agencies. There are commercial users of S&S's radar devices, sold under the name pulsEKKO, too, but at package prices from $30,000 to $50,000 the instruments were too expensive for the smaller engineering, contracting, and surveying companies S&S wanted to reach.

The challenge for S&S was to create a modified device so that it could be made and sold profitably in large numbers for about $10,000. What's more, the less expensive version still had to be tough enough to go wherever it was needed.

S&S's original line of ground penetrating radars is for deep soundings and reconnaissance in rough terrain (even glaciers) as well as shallow-depth, high-resolution imaging systems for utilities, roads, and bridges. Some pulsEKKO systems are truck mounted.

"Our GPRs see service at the North and South Poles and all points in between," said Dave Leggatt, engineering vice president for S&S. "We have them in deserts, in jungles, at downtown sites, and the back of beyond. In the field, these things really take a beating."

S&S, in other words, wanted to move an already commercialized product into a larger market, where cost and effectiveness are big issues. "By cost," Leggatt said, "we mean selling price. Effectiveness refers to the ease with which a user having little or no training can use GPR to good effect in his work environment."

GPR is excellent for pinpointing buried pipe and cable, for locating steel reinforcement bar and wire in poured concrete, for analysis of bridge decking, and for finding conduits, sewers, and even previously dug trenches. Other S&S applications include archeology, forensics, environmental studies, groundwater evaluations, glaciology, mining, and finding land mines.

It was use in a challenging environment that gave Sensors & Software its first recognition outside its highly specialized turf when a pulsEKKO was used to find a squadron of missing World War II aircraft under the Greenland ice. The squadron, six P-38F Lightning twin-engine fighters and two B-17E Flying Fortress heavy bombers, was en route to England in July 1942, when bad weather and low fuel forced all eight planes down on the Greenland glacier. The 25 men in the crews were rescued, but the planes were left behind on the ice cap, 2,300 feet above sea level and 18 miles from a coast accessible by ship. The planes, known as the Lost Squadron, disappeared beneath snow and ice.

In the 1980s, a group of nostalgic aviators became convinced that the planes, almost brand-new and preserved in ice, could be restored to flying condition if they could just be found. The location where the Lost Squadron was forced down was known, and so was the ice movement- about 120 feet seaward a year. Still, it took 12 years and 12 attempts to pinpoint the first aircraft.

The first to be found, a B-17, was discovered in 1990 about 250 feet beneath the snow and ice of 48 Greenland winters. The searchers had used a magneto meter, which presented difficulties and delay because of interference from the Earth's magnetic North Pole. The other planes were pinpointed in May 1992 with the S&S ground penetrating radar. Once the B-17 was re-identified, finding others was simplified by surveying and comparisons to aerial photos made in 1942.

The search was carried out with ski-mounted equipment under cold and stormy conditions. The team had to work fast because excavation, using steam pumps, can be done only between late spring and early autumn. The group retrieved a near-perfect P-38 from the ice a piece at a time. The fighter, which the finders named Glacier Girl, is being restored at The Lost Squadron Museum in Middlesboro, Ky.

S&S believed that expanding the GPR market would require more of a conSlll1er approach to product design, even though a radar, no matter how packaged, is hardly a "consumer" product. The product clearly needed more visual appeal in its repackaging. The targeted new buyers would be less likely to respond to the same sort of utilitarian, almost clunky look that often appeals to government and scientific types.

The intended new customers were businesses such as highway contractors, building renovators, and firms providing underground location and mapping services to utility companies. A key redesign factor was packaging, and that eventually brought S&S to the door of Ove Industrial Design Ltd. Both companies are based in Toronto.

"We went to Ove because we wanted designers practiced in the art of lower-cost, higher-volume packaging," Leggatt said.

S&S wanted a molded plastic housing, preferably a high- density polyethylene for high durability. Plastics permit molding complex parts in quantities small or large, as needed. Plastics also allow for curved, ergonomic, and visually appealing shapes nearly impossible to match in machined metal.

"Previously we were limited, in large part, to machined components;' Leggatt said. "Esthetic refinements, such as compound curves, were impractical."

Besides being less flexible in design, machined parts are slower and costlier to make than molded parts.

Ove, said Leggatt, "did an impressively good job on the housings. Combined with our own redesign that reduced the box count in a typical system from five to one, the total packaging costs were reduced by an order of magnitude. As a result, we are able to market a simple GPR system targeted to commercial users for $10,000."

Working together, Ove and S&S slashed the number of separate boxes in the housings, all of which were fabricated or machined from steel. "We and Ove reworked and greatly simplified the packaging," Leggatt said. "We came down to one box from three main components and two antennas. Other components included handles and auxiliary boxes for things that plugged in or clipped on. In all) there could be up to 12 pieces required for each system."

The big learning experience for S&S was in replacing the machined steel housings for the electronic components, sort of a housing within a housing. "Ove suggested aluminum castings produced with graphite tooling," Leggatt said. "A graphite tool is far cheaper than die cast tooling and will produce 2,000 to 5,000 pieces, more than enough for our needs."

These changes in the product led to what S&S calls the Noggin family of subsurface imaging systems, which provide novice users with the ability to map subsurface areas quickly and easily. Models are designed for 8-meter and i s-meter penetration. No GPR experience is necessary to operate these systems, S&S says.

Ove used mechanical CAD/ CAM packages called PowerSHAPE and DUCTS from Delcam International Inc. of Windsor, Ontario, which presented S&S with a new experience. "For once, we could actually see what a new product was going to look like," Leggatt said. "Visualizing something new by staring at a few lines on a piece of paper is pretty hard to do." S&S also found it very easy to make any necessary changes, such as modifying a section of the housing's curved surface. In addition, Ove was able to turn out plots from the CAD files that S&S could integrate into its advertising materials.

Ove Industrial Design simplified the packaging of a ground penetrating radar system, to create a lower-priced version of the product for its manufacturer, Sensors & Software Inc. of Toronto.

Grahic Jump LocationOve Industrial Design simplified the packaging of a ground penetrating radar system, to create a lower-priced version of the product for its manufacturer, Sensors & Software Inc. of Toronto.

"Basically, what S&S faced was a packaging solution for a matrix of problems-esthetic, marketing, and mechanical design," said Tim Poupore, president of Ove Industrial Design. "Metal parts in the casings had to be minimized because they would reflect radar energy. Their placement had to be carefully calculated and thoroughly tested."

S&S wanted housings for a family of GPR products. Individual sizes are determined by the length of the antenna, which is a function of the radar's wavelength. Wavelength determines the amount of material a GPR can "see" through and the quality of the images it generates.

"Our method was to use CAD to model all the components and antennas, locate and orient them very precisely, then create a 3-D space all around them," Poupore said. "This is what we call wrapping creativity around reality. We modeled all of the component surfaces and final shapes," said Poupore, " then grossed them up to accommodate the shrinkage we could expect from vacuum forming the plastic housings. We went to a local CNC house to machine two single- sided prototype tools to make the bases and covers. We also used this tool as a pattern for the pantagraph miller that machined the aluminum vacuum-forming molds for the production runs of the Noggin's plastic housings."

Because the lid and base have an overlapping joint to create a tight seal, Ove needed a male and a female tool.

Ove was able to go directly to the machine shop and start cutting metal. "There were no prototypes per se, at least not for visual verification," said Poupore. "We never worried that this would not work for any reason. All along, the expectation was that it would work, and it did.

"We did do one small check," he added. "We test machined a corner of the cover that had a lot of fillets and blends. It worked. That was our machining test run."

Copyright © 1999 by ASME
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