Wireless connecting things, in addition to people

Posted on March 14, 2011  /  0 Comments

We first explored the idea of embedding sensors in dams so there would be better information about potential failures back in 2005 in the course of our dam safety research project. We were talking about relatively unproven RFID or electronic dust systems back then. Today it’s a proven technology, according to the NYT.

Traditionally, most systems that monitor structures’ responses to earthquakes or strong winds have been wired ones. But wireless alerts may one day be an alternative.

“Wired monitoring systems are expensive,” said Dr. Jerome P. Lynch, director of the Laboratory for Intelligent Structural Technology and an associate professor at the University of Michigan. “You have to route kilometers of wire for power and data.”

The wireless systems may also be attractive because of their sophisticated power-management software, which improves battery performance, he said. Sensors can also extend battery life by harvesting power from the sun and the wind — and even from vibrations.

The Jindo Bridge network has 663 wireless sensors, each providing a channel of information at an installation cost of about $100, far less than the thousands of dollars typically needed to install each wired channel, said Dr. B.F. Spencer Jr., a professor of civil and environmental engineering at the University of Illinois at Urbana-Champaign. Dr. Spencer directs the American-based arm of the bridge project, which also includes the University of Tokyo and the Korean Advanced Institute of Science and Technology. Batteries on the bridge network are expected to last about three years before they need replacement.

Mark Sinclair, an engineer at Degenkolb Engineers in San Francisco who has worked on several wired monitoring systems in buildings, said the wireless systems could find some use after an earthquake, for example, to confirm a lack of damage to a structure.

But Mr. Sinclair is skeptical of their general deployment for alerts. Unlike their wired counterparts, “wireless systems don’t have a proven track record yet,” he said.

“I don’t know about your wireless signal,” he said, referring to telephone service, “but mine is chronically unreliable.”

The Jindo network has built-in features to provide backup, Dr. Spencer said. “We’ve developed reliable algorithms to make sure we get the data we need from the sensors,” he said. “We store the data locally. If wireless data is interrupted, we can resend it.”

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