The PC Goes Ready-to-Wear

Once hand-crafted, one-of-a-kind devices, wearable computers are now mass-marketed and available off the rack--and the next generation may be virtually unnoticeable

13 min read
photo of user wearing the IBM Wearable PC prototype
The IBM Wearable PC prototype packs the computing power of a Thinkpad 560 laptop computer into a package the size of a personal stereo.
Photo: Nicholas Eveleigh

Concentrating the computational power of a multimedia desktop or laptop computer into a central processing unit only slightly larger than a hand-held organizer, wearable PCs are finding plenty of users in the commercial world.

On assembly lines they are welcome in tight and busy quarters where even a laptop computer has no surface on which to perch. Others in industry are being used to help repair factory equipment, inspect airplanes and track repairs, or keep tabs on inspection equipment that must be brought on site and then removed. Physicians are using them to access patients' charts and e-mail messages. And anyone who has tried unfolding a laptop in an airplane's cramped cabin might prefer this small PC, too.

What wearable computers have to offer is job-critical information to people whose hands must be free for other work. Assembly line workers, for example, can access a database and look at drawings of what's being worked on and see step-by-step instructions for putting it together. These are shown on a small color display that hangs before a worker's eye, supported there by a head-mounted boom.

The rest of the system--its central processing unit (CPU), which includes a microprocessor, RAM, and hard drive--is worn in a belt around the waist. The display is a small liquid-crystal chip, whose image is picked up by a silvered mirror, or transmitted through a prism, and reflected or redirected into the user's eye. The display is held at the end of a toothbrush-sized boom, supported by a headboard, say, or by a larger eye-covering mirror or prism arrangement. Thanks to magnifying optics and despite the closeness of the image to the eye, the viewer has the illusion of reading a normal-sized desktop screen at the usual arm's length viewing distance.

Commands are either keyed into a small keyboard worn on the wrist or spoken into a microphone. A video camera is an option, and the computers have standard I/O ports for adding peripherals. In addition, the machines can handle off-the-shelf applications, such as database management and word processing, written for Windows or Linux operating systems.

Just what is displayed varies, of course, depending upon the imagination of the system designer and the application. The computers are not cheap, ranging from US $5000 to $10 000. They may be worth it, though, for what they can add to a person's job effectiveness.

Out on the assembly line

With a CPU the size of a Walkman-style personal stereo, IBM Corp. is testing about 100 handmade units worldwide. None is yet for sale, but the machine has nonetheless become familiar, at least conceptually, to the U.S. public at large because of a widely aired television commercial. Its hero is a young entrepreneur feeding pigeons in Venice's St. Mark's Square while viewing financial charts in the tiny eyepiece of a head-mounted display and shouting "buy" and "sell" orders for his commodities investment account back home. Intones an announcer for IBM: "The voice-activated wearable computer. It may be far out, but it isn't far off."

IBM configurationThe configuration includes (above, from left to right) IBM's head-mounted display, a video output adapter, the central processing unit, and a hand-held mouse pointing device.Photo: Nicholas Eveleigh

Back in the real world, one IBM Wearable PC prototype [Fig. 1] is being tried out on an assembly line for electric power generators at a General Electric Co. subsidiary. Containing a Pentium 233 MMX processor, 64MB RAM, and 680-MB hard drive, the prototype is equivalent to an IBM ThinkPad 560X notebook computer. Yet it is much smaller, measuring 26 by 80 by 120 mm and weighing 400 grams.

The unit provides technicians wearing it, either on a belt or in an IBM-designed vest, not only with on-the-spot access to assembly diagrams, but other information as well. There are, for example, diagrams of the equipment already installed in the power station destined to receive the new generator, along with floor layouts. With these details, GE assemblers are able to ascertain what must be done to make the new equipment fit with the old.

The database in the wearable PC's hard drive also holds disassembly procedures for GE technicians called upon to travel to a utility and take apart and repair generators that have malfunctioned. The unit's 14-by-8-mm liquid-crystal display (LCD) and optics provides the illusion that these images are being seen on a 400-mm-diagonal desktop screen.

Views are selected by a pointing device, as with a normal Windows machine, to open menu items and files. The device is a two-button eraser-sized mouse replacement that responds to finger pressure and hangs from the CPU's serial port.

A version of the IBM wearable is also being tested by doctors on their rounds at Duke University Hospital in Durham, N.C. The big difference between the unit being tested by GE and this unit is that the Duke unit has a wireless modem PC card plugged into a standard expansion slot. The doctors can read e-mail, access patients' charts, and receive diagnostic reports wirelessly and more conveniently than they could if they had to tote around a notebook PC. Primary input is by voice, with the microphone supported by the headband.

Talking to the machine

Xybernaut MA-IV devices(2) Wearable PCs, like the Xybernaut MA-IV devices shown here, are used mostly in industrial settings where hands-free computer use can justify a system's US $5000 to $10 000 cost. Maintaining an accurate parts inventory in real time (top) can be done on a wearable PC running Legacy database software. The software is written for standard operating systems Windows or Linux, using a touch-sensitive screen for input. On an assembly line (bottom), where using a desktop or laptop PC would be awkward, a wearable PC is used to consult equipment diagrams on a head-mounted display.Photos: Xybernaut Inc./Nicholas Eveleigh

Several vendors already offer voice-controllable wearable PCs off the rack. The best-selling system to date is the $5000 Xybernaut Mobile Assistant IV (MA IV), which is used with other kinds of input devices, as well [Fig. 2].

One user of the MA IV is Framatome Technologies Inc., of Lynchburg, Va. The company's inspection of steam generators in nuclear power plants is expedited by the computer maintaining an inventory of test equipment as the instruments are brought in and leave the site. A technician scans equipment with a barcode scanner attached to the MA IV PC, which is worn underneath a radioactivity containment suit.

The system's CPU--at 63 by 117 by 190 mm and weighing 795 grams--is larger and heavier than IBM's, and a 6-hour hot-swappable lithium-ion battery in a separate package adds another 500 grams to it. But its design is similar to the IBM prototype: it has a 233-MHz processor, 64MB RAM, and a 2.1-GB hard drive. It runs a customized database application written in the de facto software standards Visual Basic and SQL.

Another MA IV user is BOC Gases, in Murray Hill, N.J., a supplier of industrial gases for manufacturing. BOC technicians maintain temperature and process control equipment on the line by roaming beyond the control room, checking sensors and identifying problems. Through their wearables, they can access repair manuals for the company's various types of process manufacturing equipment. Voice recognition is useless in such a noisy environment, so input is handled by a smallish alphanumeric keyboard (142 mm by 65 mm by 12 mm) strapped to a wrist--a frequent addition to wearable PC systems.

Taking over for IBM

The maker of the MA IV is Xybernaut Corp., of Fairfax, Va., a 10-year-old firm with just over 100 employees. In May, the company announced an agreement with IBM's Purpose Optimized Device Solutions Group in Rochester, Minn., the division responsible for deriving income from specialized computers. The two are to design, develop, and manufacture the next model of the IBM Wearable PC. This will be the follow-on product to the prototype now being tested by GE. Due in 2001, it will bear the Xybernaut name.

Big Blue's decision to move into wearable partnerships is part of the giant firm's current strategy of concentrating on core businesses while profitably licensing research and design to other vendors. The Wearable PC prototype began as a feasibility study at IBM's Embedded Systems Business Unit, in Yamato, Japan. Once two successful prototypes were built, it became the responsibility of IBM's Personal Systems Group in Somers, N.Y., and Research Triangle Park, N.C., to test the units' marketability in the United States and elsewhere.

All along, it was clear that a wearable PC would not become a new line of business for IBM, especially given the Personal Systems Group's own recurring PC losses. Xybernaut's experience with wearables made the small company a natural partner for the IBM division in Minnesota.

"The market is not big enough for IBM to enter," said Xybernaut chief executive officer Ed Newman. Indeed, with total sales of wearable computers to date in the mere thousands of units, wearable PCs are at a level of commercial development analogous to personal computers in early 1977. This was the period before Radio Shack and then IBM entered the field, when a handful of small start-ups, like Apple Computer and Microsoft Corp. with its Basic software for programmers, were defining what would become standards for the PC industry.

On the other hand, wearable PCs draw on a technology infrastructure undreamed of by personal computing's pioneers. Many of the enabling technologies for the leading-edge wearable systems are identical to those found in today's laptops and other portable devices. For example, batteries in most commercial wearables are the same lithium-ion cells used in notebook models. The same is true of hard drives, with the widely used 1-inch IBM Microdrive recently boosting its capacity from 340 MB to 1 GB.

Also affecting the design of wearables are processor speed and power conservation improvements, which are being stoked by more competition for the future of wireless computers and cell phones. Intel's new low-power 600-MHz Pentium III and newcomer Transmeta Corp.'s 5400 Crusoe processor (running up to 700 MHz) are the opening salvo in a low-power technology battle that will no doubt benefit future wearable PCs.

Pictures at a shipyard, inspections in a hangar

In the meantime, Xybernaut's principal competitor in wearable PCs is ViA Inc., a seven-year-old firm based in Burnsville, Minn. Its current model ($5000 base price), the ViA II PC, is also being adopted in industrial settings. At the Bath Iron Works in Bath, Maine, a shipbuilder and refurbisher, inspectors use this wearable PC with an integrated charge-coupled-device camera and wireless phone link to take digital pictures of trouble spots on the ship and relay them to an intranet site in the yard. There a design engineer can review the photos and recommend repairs.

The Via II PC's central processing unit(3) The Via II PC's central processing unit is divided in two, with a sheet of magnesium alloy running through both halves. The alloy acts as a heat sink to dissipate heat from the system's processor chip.Photo: Via Inc.

Unique among wearables, the Via II PC divides its CPU in two [Fig. 3]. It has a pair of Palm Pilot-sized components (a processor and 64MB RAM in one, 3.2 GB hard drive and I/O connectors in the other) joined by a flexible articulation, so the CPU can ride more comfortably around the wearer's waist. The two parts measure 254 mm by 78 mm by 31 mm and they weigh 650 grams. A 500-gram battery is worn separately.

Like many users of ViA II PCs, Northwest Airlines' inspectors and mechanics documenting fleet repairs have opted for a hand-held indoor-readable 16.5 mm-diagonal color display/touch-sensitive tablet, instead of a head-mounted display. This wearable PC was the system chosen for eliminating a slow in-triplicate paper trail used previously for assigning nonroutine repairs for Northwest's airliners.

In the hangar for scheduled maintenance to hydraulics, brakes, and tires, the plane being inspected can accrue hundreds of requests for nonroutine repairs to broken seats, torn carpet, or worn paint. With this system, parts numbers and their accompanying repairs can be entered quickly using a bar code scanner that reads appropriately coded labels. The system reportedly helped reduce work hours for nonroutine inspection of a Boeing 747 by a third.

In hangars, where temperature extremes are common, the ViA II has proven rugged. Its split-unit design doubles the surface area available for a heat sink, which is made of a single sheet of magnesium alloy spanning both halves of the computer. The sheet dissipates heat from the wearable PC's processor (currently a Cyrix MediaGX chip running at 166 MHz; a 400-MHz processor is due later this year).

Not by voice alone

A key advantage of the wearable is that it breaks with the PC's clunky legacy of an alphanumeric keyboard for a primary input device and as large a screen as possible for output display. The wearable's hands-free operating imperative makes it the first PC configuration to feature voice-control for input and a miniature display for output. Currently, voice recognition and head-mounted displays are the I/O choices for most wearable PCs being sold or tested. But there are drawbacks.

Anyone expecting an IBM Wearable PC prototype to perform at the level of real-time voice recognition depicted in the television commercial it inspired is bound to be disappointed. "You'd have to wait 10 seconds after some voice commands because of processing time," said Bruce Knaack who, as manager of licensing and solutions for IBM's Personal Systems Group, Research Triangle Park, N.C., oversees the pilot tests of the Wearable PC prototypes.

Running off-the-shelf IBM Via Voice software, the 233-MHz processor in the IBM Wearable PC prototype or the Xybernaut MA IV can interpret basic Windows and software commands, like "File Open Spreadsheet October 2000," with little perceptible lag. But faster processor speeds are needed to cut delays for complex phrases, like "Gimme soybeans, scroll up, up, yeah, yeah, yeah, buy it, buy it, buyyyy it!" as was featured in the TV commercial for the product.

Another solution is to move voice processing from the central processor to a separate chip. Xybernaut's IBM Wearable PC in product form will incorporate Texas Instruments' digital signal processing (DSP) chip, the TMS320C5000, which is already used in cellular telephones and other mobile applications. "We'll be first with speech recognition built into a wearable PC motherboard instead of in software," said Xybernaut's Ed Newman, adding, "Right now, 90 percent of our customers order speech recognition software with the systems they're buying."

But even for hands-free users, a voice input-only wearable PC may not always make sense. "There are some situations where speech is in-appropriate, when you're working in a public area, or when you're at a meeting taking notes," said Chris George, president and founder of Handykey Corp., Mount Sinai, N.Y., which makes a "chorded" keyboard. Resembling a stenotype machine, this keyboard allows one-handed input of text, numbers, and user-assigned macro commands [Fig. 4].

The Twiddler chorded keyboard(4) The Twiddler chorded keyboard is designed for one-handed input. Its array of 12 finger keys and six thumb keys requires training; frequent users can enter text at close to two-hand touch-typing speeds.Photo: Nicholas Eveleigh

HandyKey's Twiddler keyboard incorporates a decidedly unintuitive interface with 12 finger keys (in a 3-by-4 matrix), and six thumb keys. More than one key must be pressed at a time to obtain a character or command. Trained users can enter text at close to two-hand touch-typing speeds.

For those who prefer a compact Qwerty-style keyboard, the de facto standard for wearables (usually strapped to a wrist) is the WristPC keyboard from L3 Systems, of Redmond, Wash. Used at BOC Gases, the keyboard, introduced in 1998, is offered as an option for both Xybernaut's MA IV and IBM's Wearable PC prototype. It was originally developed as a rugged keyboard for U.S. Special Forces.

A choice of displays

As for the display, most computer wearers prefer a small LCD and magnifying optics close to the eye, though some, as noted, opt for a laptop-style LCD strapped to a wrist. No one head-mounted display offers all the advantages: brightness and low power consumption, high resolution and large apparent size. Still, most of them provide remarkably bright full-color images, visible in all but the brightest sunlight.

Displays for wearables are being supplied by at least a half dozen vendors. The IBM Wearable PC prototype is being tested with two types. One display, the PC Eye-Trek from Japan's Olympus Optical Co., Tokyo, uses a 14-mm-by-18-mm reflective field-sequential display that is lit from the outside. It's manufactured by Colorado MicroDisplay, in Boulder, and relies on an innovative liquid-crystal-on-silicon technology, in which liquid crystals are applied directly to a silicon backplane instead of glass [see Innovations, IEEE Spectrum, April 2000, p. 24].

The rest of the IBM prototypes rely on a display developed at its Thomas J. Watson Research Center in Yorktown Heights, N.Y. This display, the CyberDisplay 640-color module (14 mm by 18 mm) is being built by Kopin Corp., Taunton, Mass., with more traditional transmissive active-matrix LCD technology. While the bulkier Olympus headmount from Japan provides a SVGA (Super Video Graphics Array) quality display with a full 800 by 600 pixels, the IBM display offers VGA (Video Graphics Array) quality over 640 by 480 pixels, but uses less power and has a smaller optical element borne on the headset.

For Xybernaut's displays, the company has announced an alliance with Microvision Inc., Bothell, Wash., makers of an unusual display that uses a laser diode to scan an image directly on the retina [see Innovations, Spectrum, January 1999, p. 112]. It is the only display readable in intense sunlight. Unlike the full-color palette available with most other head-mounted displays, the Retinal Scanning Display to be sold with Xybernaut systems will be available in red only.

Georgia Institute of Technology's Thad Starner views video output(5) Georgia Institute of Technology's Thad Starner views the video output from his latest Thin Lizzy wearable PC reflected onto his glasses. The display, from MicroOptical Corp., is lightweight and compact enough to be worn comfortably for hours at a time.Photo: Samogden/Photo Researchers Inc.

For many of the pioneers of wearable computers, there is still only one choice in miniature screens: an eyeglass-borne display from MicroOptical Corp. of Westwood, Mass [Fig. 5]. Available in quarter-sized and full-sized VGA formats, the MicroOptical display consists of a 1-cm-diagonal LCD housed in a casing that clips on the temple of reading- or sunglasses. A transparent plastic light pipe leading from the display element projects its image onto a tiny mirror on one of the lenses in front of the viewer's eye. Requiring no external headmount, this display brings wearable PCs closer to two essential long-term goals: persistence and stealth.

Persistence is Thad Starner's term for the ability to wear a computer all the time and not tire. An assistant professor at the Georgia Institute of Technology, Starner wears his handmade system all his waking hours. He has it constantly available to store the names of people he meets, record bits of conversation, or call up information on the Internet, while simultaneously maintaining eye contact with colleagues and students.

The possibility of wearable PCs going unnoticed when worn is another reason for their use. Stealth matters a lot to those who may be next to adopt these computers--most likely the visually challenged and electronic news gatherers, who have their own reasons to go unnoticed, according to Steve Mann, assistant professor in the department of electrical and computer engineering at the University of Toronto. Usually clad in his own wearable computing creation, with sunglasses shielding a combined display and camera, Mann recently joined Xybernaut's board of advisors.

Given all the advances made in wearables, what is likely to occur in their future? Some of the current drawbacks to wearable PCs' comfort and compactness will most probably be resolved by technologies already in the pipeline. Bluetooth and other wireless protocols should eliminate the inconvenient, and even hazardous, dangling cables between the CPU and the microphone, keyboard, head-mounted display, and other peripherals. They should also provide low-power, high-bandwidth access to the Internet.

CPU sizes are also drastically shrinking. For example, Tiqit Computers in Palo Alto, Calif., recently announced a Windows- and Linux-running CPU the size of a matchbox, including an Advanced Micro Devices 66-MHz processor, 16MB RAM, and an IBM 340-MB MicroDrive.

Still, the goal of wearable units blessed with persistence and stealth may be a decade away. That's according to Gene Frantz, the Dallas-based Texas Instrument senior fellow in digital signal processing and the DSP liaison to Xybernaut. Frantz predicts: "In 10 years, a wearable computer will be so small, it's part of me rather than something I wear."

Spectrum editor: Tekla S. Perry

To Probe Further

The Fourth International Symposium on Wearable Computers will be held 16-18 October in Atlanta, Ga. For registration information, see the Web site at Full bibliographic information on conference proceedings for the First, Second, and Third symposiums may be accessed at the same Web site. They are also available from the IEEE's on-line Catalog Store at

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