Gesture-recognition technology based on Wi-Fi could allow people to control their electronics from any room in the home.
University of Washington (UW) computer scientists have shown it is possible to leverage the Wi-Fi signals around us to detect specific movements without needing sensors on the human body or cameras.
By using an adapted Wi-Fi router and a few wireless devices in the living room users could turn off lights with a simple finger-swipe or change the song playing on their music system in the next room by moving their hand to the right.
“This is repurposing wireless signals that already exist in new ways,” said lead researcher Shyam Gollakota, a UW assistant professor of computer science and engineering. “You can actually use wireless for gesture recognition without needing to deploy more sensors.”
The UW research team, which includes Shwetak Patel, an assistant professor of computer science and engineering and of electrical engineering and his lab, have called the technology 'WiSee' and will unveil it at the 19th Annual International Conference on Mobile Computing and Networking in September.
The concept is similar to Xbox Kinect, which uses cameras to recognise gestures, but the UW team’s technology is simpler, cheaper and doesn’t require users to be in the same room as the device they want to control as Wi-Fi signals can travel through walls and aren’t bound by line-of-sight or sound restrictions.
The UW researchers built a “smart” receiver device that essentially listens to all of the wireless transmissions coming from devices throughout a home, including smartphones, laptops and tablets. A standard Wi-Fi router could be adapted to function as a receiver.
When a person moves, there is a slight change in the frequency of the wireless signal and moving a hand or foot causes the receiver to detect a pattern of changes known as the Doppler frequency shift.
These frequency changes are very small – only several hertz – when compared with Wi-Fi signals that have a 20 megahertz bandwidth and operate at 5 gigahertz.
But the researchers developed an algorithm to detect these slight shifts and the technology also accounts for gaps in wireless signals when devices aren’t transmitting.
The technology can identify nine different whole-body gestures, ranging from pushing, pulling and punching to full-body bowling.
The researchers tested these gestures with five users in a two-bedroom apartment and an office environment and out of the 900 gestures performed, WiSee accurately classified 94 per cent of them.
“This is the first whole-home gesture recognition system that works without either requiring instrumentation of the user with sensors or deploying cameras in every room,” said Qifan Pu, a collaborator and visiting student at UW.
The system requires one receiver with multiple antennas, with each antenna intuitively tuning into a specific user’s movements so that as many as five people can move simultaneously in the same residence without confusing the receiver.
WiSee technology uses multiple antennas to focus on one user to detect the person’s gesture and if a person wants to use the WiSee, they would perform a specific repetition gesture sequence to get access to the receiver.
This password concept would also keep the system secure and prevent a neighbour – or hacker – from controlling a device in your home.
Once the wireless receiver locks onto the user, he or she can perform normal gestures to interact with the devices and appliances in the home and the receiver would be programmed to understand that a specific gesture corresponds to a specific device.
Collaborators Patel and Sidhant Gupta, a doctoral student in computer science and engineering, have worked with Microsoft Research on two similar technologies – SoundWave, which uses sound, and Humantenna, which uses radiation from electrical wires – that both sense whole-body gestures.
But WiSee stands apart because it doesn’t require the user to be in the same room as the receiver or the device, resulting in a smart home where users could turn off the oven timer with a simple wave of the hand or turn on the coffeemaker from their bed, a genuine possibility.
The researchers plan to look next at the ability to control multiple devices at once. The initial work was funded by the UW department of computer science and engineering.
Visit www.facebook.com/eandtmagazine for a video demonstrating the technology.
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