We use Wi-Fi to stay connected, but what if Wi-Fi could also be used to sense the world around us – even behind walls?
The world wants to be connected to the internet at all times, and as a result we’re bombarded by Wi-Fi almost everywhere we go. Yasamin Mostofi, Associate Professor in the Department of Electrical & Computer Engineering at UC Santa Barbara, wanted to know can we use them not just for connectivity, but for sensing?
Using nothing more than a Wi-Fi card and a receiver, Mostofi has shown that it’s possible to see through walls – useful for search and rescue – as well as sense the number and location of people in a building, which could transform smart lighting and HVAC technology.
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An earthquake strikes a major city, a large building collapses and people are trapped inside. How can rescuers know how many people are trapped and where they are? A UC Santa Barbara researcher may have a solution using something that’s around us all the time: Wi-Fi.
If you’ve ever tried to connect to the internet when there’s distance and walls between you and your router, Wi-Fi signals are affected by the environment. They lose energy as they pass through objects, like light through a lampshade, and they can bounce off of objects, like light off a mirror.
“Our first interest was x-ray vision with Wi-Fi,” said UC Santa Barbara’s Yasamin Mostofi. “We basically wanted to see if we can see behind walls with Wi-Fi signals.”
And if that doesn’t sound fantastic enough, Mostofi decided to throw some robots into the mix.
“We’re also interested in robots. We wanted to see if we can give x-ray vision to unmanned vehicles with only Wi-Fi signals.” To test the system, Mostofi and her lab constructed a tall, square enclosure out of brick on the UCSB campus. In the middle, they placed objects: a barrel, two barrels, a graduate student.
To peek through the wall, two remote vehicles passed around the enclosure.
“One robot transmits, and that transmission goes through the object,” explained Mostofi. “The objects interact with it, depending on their material property and their location.”
The objects leave a signature on the Wi-Fi signal. Once the other robot receives the signal, the trick is to then reconstruct what the signal passed through.