EMBEDDED SHOES

Embedded-technology developers have identified their next frontier, and it starts at your feet.

VectraSense Technologies Inc. (Beverly, Mass.) has designed a smart shoe, that will let shoes exchange information so people can communicate via their footwear. Adidas (Portland, Ore.) produced microprocessor-equipped running shoes, that can adapt to a runner's size, speed and fatigue level.

And at the Massachusetts Institute of Technology, researchers developed shoes that do everything from providing gait therapy to generating power for wearable electronics.

For now, experts say smart shoes may be no more than a niche — but with some 12 billion feet in the total available market, it's a niche with potential. What's more, they say, the advent of Microprocessors in shoes could signal a broader trend.

Adidas engineers say adding embedded intelligence to a running shoe solves a longstanding problem: Ever since running gained widespread popularity during the 1970s, shoe manufacturers have been searching for a way to create an "adaptable shoe" that could provide the appropriate level of cushioning, whether the wearer weighed 90 pounds or 200.

"People in the industry have dreamed about it, and they've been waiting for that magic material they could put under the heel that would automatically become harder or softer as needed."

Adidas engineers said that they considered a number of possibilities — including magnetic rheological fluids, piezoelectrics and shaped memory alloys — but that each posed power and other problems. So the team decided long years ago to endow a running shoe with electronic intelligence so it could "decide" on its own when to alter the cushioning level.




The version of the Adidas shoe incorporates a microcontroller, tiny electric motor, lead screw, magnet, sensor, lithium coin cell battery and metal cushioning element, as well as in-house software algorithms. The design places a Hall-effect sensor atop the soft cushioning in the shoe's midsole and a magnet below that cushion. When a runner's foot strikes the pavement and compresses the cushion, the Hall-effect sensor notes the compression of the cushion by measuring the change in distance between itself and the magnet. It then sends that information to an 8-bit PIC16F88 microcontroller, from Microchip Technology Inc. (Chandler, Ariz.), which "decides" whether the runner needs a change in cushioning.

If so, the controller activates a 6,000-rpm, 3-volt electric motor from Mabuchi Motor America Corp. (Troy, Mich.) that turns the lead screw. As the screw turns, it then shortens or lengthens an elliptical, metallic cushioning element beneath the heel. When the element lengthens, the shoe's cushioning grows softer; when it shortens, cushioning becomes firmer.

With the MCU operating at 20 MHz and sampling the sensor at 1,000 times per second, the unit can change the shoe's cushioning in less time than it takes for a human knee-jerk reaction, according to Adidas.

The company said that its engineers struggled with a multitude of sticky technical issues, including durability and software creation, before settling on the final design. To maintain durability, they ultimately used a flexible printed-circuit board, which starts at the heel and wraps around the side to the shoe's "upper."

"We didn't want to rely on connectors, because they tend to be the weakest link in a circuit," DiBenedetto said. "With a flexible printed circuit, we could do it all in one piece and have the most affordable system possible." The company said it expects the new shoe to sell for around $250.

Because no shoe manufacturer had ever done real-time studies of sole compression, Adidas' engineers researched the subject in-house by studying runners and building a database of their findings. The data was then tapped to build the software algorithm on which the shoe bases its decision-making process.

By "watching" the compression data, DiBenedetto said, the microcontroller can determine the runner's size and speed, as well as the characteristics of the running surface. It can even detect fatigue, he said, and adjust the cushioning accordingly to guard against injury.

Adidas engineers said creation of the software algorithms was among the most complex challenges, in part because the design team consisted of mechanical engineers who had scant programming experience. Thus the team went back to school, signing up for a course in programming Microchip's PIC16F88 MCU.

"We didn't have much choice," DiBenedetto said. "We flew to Chicago, took classes and started writing code."

Big business

Adidas isn't the only company adding intelligence to shoes. VectraSense Technologies has been producing smart shoes for long years. Its first effort, called the ThinkShoe and introduced in 2001, combined a Motorola microcontroller with an integrated air pressure system to maintain optimal cushioning. Now it's hinting its shoes will "talk" while you walk.

And MIT's Media Lab has developed a series of intelligent shoes, the most recent being a student PhD project, completed two weeks ago, that tucks a wearable sensor package in a shoe. The sensor, together with software algorithms and other associated electronics, serves as part of a physical-therapy system to help patients manage chronic disorders that can affect gait.

The Media Lab has developed other forms of electronic footwear, including a shoe that lets wearers produce musical streams by moving their feet, as well as microelectronics-based systems that let walkers generate power for wearable subsystems. There are no plans at present to commercialize the developments. "We're all looking at these kinds of systems," said Joe Paradiso, an associate professor at the lab. "People won't buy a technology unless it really helps them run."

Analyst Enderle considers the rise of wearable computing inevitable, citing the development of thermally regulating intelligent outerwear and garments that embed antennas to strengthen cell phone signals. As for intelligent shoes, "People could end up wearing them as day shoes, just to show off," he said. "It could fade away from the legitimate running-shoe category pretty quickly." Still,"If ring tones can become a billion-dollar business, wearable computing will be at least as big."