Massachusetts Institute of Technology researchers have developed a
device that can see through walls and pinpoint a person with incredible
accuracy. They call it the “Kinect of the future,” after Microsoft’s
Xbox 360 motion-sensing camera.
Shown publicly this week for the first time, the project from MIT’s
Computer Science and Artificial Laboratory (CSAIL) used three radio
antennas spaced about a meter apart and pointed at a wall.
Photo: Nick BarberMIT has developed way to pinpoint the location of someone through a wall using just radio signals.
A desk cluttered with wires and circuits generated and interpreted the
radio waves. On the other side of the wall, a person walked around the
room and the system represented that person as a red dot on a computer
screen. The system tracked the movements with an accuracy of plus or
minus 10 centimeters, which is about the width of an adult hand.
Fadel Adib, a Ph.D student on the project, said that gaming could be one
use for the technology, but that localization is also very important.
He said that Wi-Fi localization, or determining someone’s position based
on Wi-Fi, requires the user to hold a transmitter, like a smartphone
for example.
“What we’re doing here is localization through a wall without requiring
you to hold any transmitter or receiver [and] simply by using
reflections off a human body,” he said. “What is impressive is that our
accuracy is higher than even state of the art Wi-Fi localization.”
He said that he hopes further iterations of the project will offer a real-time silhouette rather than just a red dot.
In the room where users walked around there was white tape on the floor
in a circular design. The tape on the floor was also in the virtual
representation of the room on the computer screen. It wasn’t being used
an aid to the technology, rather it showed onlookers just how accurate
the system was. As testers walked on the floor design their actions were
mirrored on the computer screen.
One of the drawbacks of the system is that it can only track one moving
person at a time and the area around the project needs to be completely
free of movement. That meant that when the group wanted to test the
system they would need to leave the room with the transmitters as well
as the surrounding area; only the person being tracked could be nearby.
At the CSAIL facility the researchers had the system set up between two
offices, which shared an interior wall. In order to operate it,
onlookers needed to stand about a meter or two outside of both of the
offices as to not create interference for the system.
Photo: Nick BarberAn MIT project can track a user with an accuracy of +/- 10 centimeters.
The system can only track one person at a time, but that doesn’t mean
two people can’t be in the same room at once. As long as one person is
relatively still the system will only track the person that is moving.
The group is working on making the system even more precise. “We now
have an initial algorithm that can tell us if a person is just standing
and breathing,” Adib said. He was also able to show how raising an arm
could also be tracked using radio signals. The red dot would move just
slightly to the side where the arm was raised.
Adib also said that unlike previous versions of the project that used
Wi-Fi, the new system allows for 3D tracking and could be useful in
telling when someone has fallen at home.
The system now is quite bulky. It takes up an entire desk that is strewn
with wires and then there’s also the space used by the antennas.
“We can put a lot of work into miniaturizing the hardware,” said
research Zach Kabelac, a masters student at MIT. He said that the
antennas don’t need to be as far apart as they are now.
“We can actually bring these closer together to the size of a Kinect
[sensor] or possibly smaller,” he said. That would mean that the system
would “lose a little bit of accuracy,” but that it would be minimal.
The researchers filed a patent this week and while there are no
immediate plans for commercialization the team members were speaking
with representatives from major wireless and component companies during
the CSAIL open house.