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WiSee offers through-wall gesture recognition

WiSee offers through-wall gesture recognition

The WiSee system tracks a user's gestures by looking for tiny Doppler shifts in Wi-Fi signals, giving it the ability to work even through walls.

A group of researchers from the University of Washington's Department of Computer Science and Engineering have developed a method of recognising a user's gestures regardless of where in the house they might be - using nothing more than existing Wi-Fi signals.

Dubbed WiSee, the system claims to be able to recognise gestures both in line-of-sight from the equipment and in non-line-of-sight. More impressively, the WiSee technology also works through walls: meaning you could, for example, pause a video playing in the living room while taking a quick bathroom break.

The system works by looking for the Doppler shift of a wave as it moves relative to the observer - the compression or expansion in frequency that causes an ambulance siren to appear higher-pitched as it is travelling towards the observer and lower-pitched as it travels away. Applying this well-known phenomenon to Wi-Fi signals, the team has worked out a way to track the Doppler shift that comes from a hand moving towards or away from the receiver unit itself.

It's a system that requires incredible accuracy: a Wi-Fi signal works on a channel that spans around 20MHz, and operates at the speed of light; the Doppler shift that comes from a teeny-tiny human hand moving somewhere within the transmission path is a handful of hertz - a vanishingly small percentage change to the frequency of the signal. The team claims to have cracked that problem, transforming the received signal into a narrowband pulse with a frequency of just a few hertz which can be tracked for Doppler shifts.

The team's work is an extension of previous attempts to track the occupants of a room using Doppler shifts in Wi-Fi and mobile signals. Unlike that research, which was targeted at creating a means for law enforcement, military and emergency service personnel to see 'through' walls, WiSee has definite civilian applications.

In prototype form, the system has proved successful: the team's proof-of-concept implementation, using high-price Ettus USRP N210 equipment, has been tested in a two-bedroom apartment as well as an office environment with a claimed accuracy of 94 per cent in detecting gestures and translating them into control of a connected computing device.

Unlike rival systems, like Microsoft's Kinect or the soon-to-launch Leap Motion, the system is completely independent of line-of-sight requirements: the user doesn't even need to be in the same room as the machine he or she is controlling. Better still, while the prototype uses expensive signal processing gear, the team claims that the system is suitable for implementation on existing wireless access point hardware - pointing to a future where gesture control arrives as standard.

Qifan Pu, lead researcher on the project, claims that the system can use Multiple Input Multiple Output (MIMO) Wi-Fi hardware to eliminate interference from people other than the user who might be waving their hands around, locking the tracking to the active user. The system also includes a 'startup sequence' of gestures that must be performed before the WiSee software will accept commands, acting as both a personal identifier for a given user and as a means to stop the system rebooting your computer every time you scratch your nose.

The team has published a working draft paper (PDF warning) of its research, as well as a demonstration video reproduced below.

9 Comments

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ya93sin 5th June 2013, 10:44 Quote
Forgive me if I'm wrong but if I wanted to go to the bathroom during a movie I'd pause before I leave. If I wanted to control the screen from behind a wall I'd be questioning my own sanity.
Gareth Halfacree 5th June 2013, 11:02 Quote
Quote:
Originally Posted by ya93sin
Forgive me if I'm wrong but if I wanted to go to the bathroom during a movie I'd pause before I leave. If I wanted to control the screen from behind a wall I'd be questioning my own sanity.
What, you've never been caught short and had to dash out of the room? That was merely an example. How about the following?

Change the track or volume of an in-house audio system (a la Sonos) with a gesture from any room.
Control your heating (or AC) system with a gesture from any room.
Dim or brighten your lights with a gesture from any room.
Mute your incessantly-ringing landline with a gesture from any room.
Trigger a manual backup with a 'face-palm' gesture from any room.

I, for one, welcome our new gesture-tracking overlords. <waves arms in supplication>
Stanley Tweedle 5th June 2013, 11:03 Quote
Quote:
Originally Posted by ya93sin
Forgive me if I'm wrong but if I wanted to go to the bathroom during a movie I'd pause before I leave. If I wanted to control the screen from behind a wall I'd be questioning my own sanity.

Yes, you have done something none of the scientists were able to do... recognise that gesture control while you're having a bath or having a poo is actually a waste of time. I can imagine kids would exploit it no end though... Can you imagine little johnny in his bedroom giving a gesture to pause the porn his parents are watching downstairs?
Blackshark 5th June 2013, 11:19 Quote
The ultimate problem for any of these systems is how to pick up if a movement is meant / directed towards the system - or is completely unrelated. Its very clever - they all deserve a pat on the back. However it is completely impractical.

Anyone with young kids will be immediately assaulted with the washing machine exploding, half the house warming up to 100oC, frozen in the other, stereos TVs etc.. starting, stopping, getting louder or switching channel as their little bundles of joy run around.

Ill give my box(s) to you Gareth :-) and you can set up all sorts of different star jumps for every possible tech related action!
Gareth Halfacree 5th June 2013, 13:35 Quote
Quote:
Originally Posted by Blackshark
Ill give my box(s) to you Gareth :-) and you can set up all sorts of different star jumps for every possible tech related action!
Not a terrible idea - I've been packing on the pounds recently.

Incidentally, the paper (and the article) address the issue of tracking a particular user: each user gets an activation gesture, unique to them. Without the activation gesture, commands are ignored. If your kid doesn't know your activation gesture, he or she can't send any commands.

As for it being abused to set the thermostat to a hundred degrees: you guys know you can do that with an old-fashioned thermostat too, right? Mine's even wireless, so our theoretical little ess-aitch-one-tee can nick it and make the adjustments from the privacy of his or her room. The solution? Proper parenting, simple as.
edzieba 5th June 2013, 14:50 Quote
This sounds less like using WiFi for tracking, and more encoding data onto a UWB tracking pulse.
Corky42 5th June 2013, 14:52 Quote
Quote:
Originally Posted by Gareth Halfacree
If your kid doesn't know your activation gesture, he or she can't send any commands.

More like the parents wont know the gesture after little johnny sets it up for them :)
Quote:
Originally Posted by Gareth Halfacree
The solution? Proper parenting, simple as.

Yup because we have that in spades here in blighty
ya93sin 6th June 2013, 10:45 Quote
Quote:
Originally Posted by Gareth Halfacree
Quote:
Originally Posted by ya93sin
Forgive me if I'm wrong but if I wanted to go to the bathroom during a movie I'd pause before I leave. If I wanted to control the screen from behind a wall I'd be questioning my own sanity.
What, you've never been caught short and had to dash out of the room? That was merely an example. How about the following?

Change the track or volume of an in-house audio system (a la Sonos) with a gesture from any room.
Control your heating (or AC) system with a gesture from any room.
Dim or brighten your lights with a gesture from any room.
Mute your incessantly-ringing landline with a gesture from any room.
Trigger a manual backup with a 'face-palm' gesture from any room.

I, for one, welcome our new gesture-tracking overlords. <waves arms in supplication>

I don't think so, my bladder control usually allows for a second to pause the movie without having to wave my arms about.
- I would control it from inside the room before I leave. I know what volume level is good if I am outside the room so that it's not too loud.
-AC is controlled individually by a remote in each room, a waste of power to leave it on if I am somewhere else, I control it from inside the room before I leave.
-Use the light switch? Usually right by the door.
-Or just have the phone nearby so that if someone calls you can hang up.
Corky42 6th June 2013, 13:27 Quote
Quote:
Originally Posted by ya93sin
I don't think so, my bladder control usually allows for a second to pause the movie without having to wave my arms about.

Give your self a few more decades ;)
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