When devices just can’t break

Makers of ‘ruggedized’ computers put products to extreme tests.

Don’t try this with your Palm Treo. A team of designers from Symbol Technologies last year made a routine visit to a customer site to see firsthand how Symbol’s rugged-computer bar code scanners, mounted on forklifts, were being used in warehouses.

What they found set a new standard for rugged design.

During breaks, the forklift drivers chalked a bull’s-eye on a nearby wall. Then, they hung a scanner by its telephone-like stretch cord from the back of the small, nimble, propane-powered forklift. Each driver would take turns barreling the truck toward the wall and at the last second swerving away, jerking the scanner up and whipping it around to whack the chalk target. Each contestant was scored based on how close he came to the target.

Alistair Hamilton, Symbol’s vice president of industrial design, still sounds as if he can hardly believe it. “What does this do to my ‘rugged specification’ for this product?” he asks rhetorically. “It’s a problem that we identified as a whole new level of durability that we have to think about here.”

Meet the unsung and unseen heroes of rugged computing.

Hamilton, along with William Erler of Itronix, and William Roeder of LXE, oversee their respective company’s design teams that puzzle over how to make a range of products that will stand up to heavy, hard use in demanding environments.

Hamilton set out to be a mechanical engineer but found the discipline too constrained. “I wanted to look at bigger system design, and be a bit more creative and out there,” he says. He switched to industrial design and landed at Symbol eight years ago.

His comment expresses an intellectual restlessness that seems common to all three men, in a field that could be called extreme engineering. Itronix’s Erler, for example, is an avid rock climber when he gets away from his workstation. Now senior design manager for mechanical engineering, Erler, 50, got his start as a component designer for circuit boards. “We’re putting as much equipment into a small package as possible,” he says. “I liken it to a puzzle.”

Roeder, 52, vice president of product development at LXE, joined the company 19 years ago to manage the engineering department. “We needed a new handheld terminal kind of badly,” he recalls. Rugged design has offered challenges ever since.

‘Beat to hell’

All the challenges spring from one irreducible fact.

“The biggest problem is it gets beat to hell,” LXE’s Roeder says.

Rugged computers are subjected to rain, grease, freezing cold, baking heat, vibration, crashes, drops, wear, and a thousand other stresses not suffered by standard PCs in a carpeted office.

Total 2004 U.S. sales for rugged mobile computers was $1.9 billion and is expected to reach $2.2 billion in 2006, according to Venture Development Corp. (VDC), a market research firm.

VDC analyst David Krebs estimates that dollar sales of rugged laptops and tablets are about 1/30th of their non-rugged counterparts. Main markets include the military, manufacturing, logistics, warehousing, field service, public safety, retail and now healthcare.

And they’re moving into the mainstream. Itronix last year introduced its first semirugged laptop, the VR-1, including a model licensed with General Motor’s Hummer brand name. Included are durable features such as a magnesium alloy case (magnesium being the metal of choice among rugged designers), stainless-steel hinges and a shock-mounted 80GB hard drive.

Panasonic’s ToughBook division last year launched the first TV ad campaign aimed at a general mobile audience. The ads show a laptop slipping from a briefcase and shattering into hundreds of pieces, and keyboards soaking up spilled lattes like sponges. ToughBooks are shown enduring these indignities.

A blend of art and science

Designing computers to endure great punishment is a blend of art and science.

Symbol’s design team includes industrial designers, mechanical engineers, human-factors specialists and what Symbol’s Hamilton calls anthropologists, though most of them have psychology degrees. They study, in effect, the tribal behavior of rugged computing customers.

“It’s really about observation,” Hamilton says. Symbol’s researchers saw users tying string to the underside of the MC9000 handheld to carry it like a lunch pail. Designers added hooks and a strap to the device.

“It’s all about trade-offs,” Roeder says. “You struggle with conflicting goals.”

Sealing secrets

The conflicts are manifest in sealing a computer against liquids and dust. “People don’t realize how many openings there are in a typical laptop,” Itronix’s Erler says.

Sealing usually combines various technologies and is a big determinant of the computer’s overall structure. Designers rely on intricate combinations of grooves and grips, different plastics and various sizes of ‘O’ rings or other rubber or rubberlike gaskets.

But if you seal the computer, how do you dissipate the heat generated by its internal electronics, especially the increasingly powerful CPU? Itronix engineers created a way to conduct heat from the inside to the outside, Erler says. Instead of using aluminum heat sinks, which are essentially ridged structures that conduct heat, Itronix uses a web of tiny copper pipes that carry the heat far more efficiently and almost instantly to a set of magnesium fins outside the sealed surface.

The science of drops

The seals, like everything else on a rugged computer, have to withstand repeated drops and constant vibration, two very different forms of stress. The weakest points in a laptop are the display and the hard drive.

As a dropped computer falls, it accelerates. When it hits the floor, it decelerates abruptly, but because of momentum, the interior components want to keep going. Standard components will break and fly apart under these G-forces. “In a typical drop, you might see a couple of thousand G’s moving directly into the unit,” Erler says. “The typical hard drive will not survive that.”

So designers create an external case, and an internal skeleton, that’s as rigid as possible. Then, they cushion components such as the hard drive with a gel or foam shock mounting. But the most critical variable is leaving enough room, called sway space, inside the computer for the cushioned hard drive to move, allowing it to decelerate slowly. “You want a managed, absorbed movement inside,” Hamilton says.

Symbol’s MC9000 line, introduced two years ago, used a unique design to deal with shock and vibration. The housing is about 25% thicker than comparable products, the electronics are a free-floating package in a magnesium frame to absorb shock and minimize flexing. The halves fit together in a way that creates, in effect, a tube.

“It creates a phenomenally strong package,” Hamilton says. “We have videos from our customers of the thing being thrown off the roof of a small building, bouncing around the parking lot, and it still scans.”

Designers also focus on usability. For its GoBook laptops, Itronix engineers created the bat hook, borrowing a mountaineering term that describes a metal hook driven into a rock wall to support climbing gear. On the GoBook, the bat hook is an offset handle mounted at the rear. The user can securely hook the handle over any vertical edge, such as a steering wheel, ladder or the metal door of an electrical breaker box, creating a stable work surface.

Test it till it breaks

Testing the products is a key part of the design process, and as ingenious as the actual designs.

Itronix testers dropped GoBook laptops 52 times from a height of 3 feet, with the display closed, and with it open. It sat for four hours in an automated rain chamber, which allows the volume and rate of water fall to be calibrated. Symbol put the MC9000 in a machine resembling an oversized clothes dryer to replicate thousands of tumbles.

In other tests, the computers are strapped to machines that simulate shaking or vibration, or drops from various heights. LXE uses a device that presses a steel rod repeatedly to the display screen to test its durability.

“We test it until it fails, then we find the failure point, and tweak the design from there,” Symbol’s Hamilton says.