Indoor Navigation On Your Smartphone, Using the Earth's Magnetic Field

MrSeb writes "Researchers from the University of Oulu in Finland has created an indoor navigation system (IPS) that uses the Earth's innate magnetic field to ascertain your position — just like a homing pigeon or spiny lobster. According to IndoorAtlas, the company spun off by the university to market and sell the tech, its system has an accuracy of between 0.1 and 2 meters. The Finnish IPS technology is ingenious in its simplicity: Basically, every square inch of Earth emits a magnetic field — and this field is then modulated by man-made concrete and steel structures. With a magnetometer (compass), which every modern smartphone has, you can first create a magnetic field map — and then use that map to navigate the shopping mall, underground garage, airport, etc. Compared to most other IPSes, which require thousands of WiFi or Bluetooth base stations to achieve comparable accuracy, IndoorAtlas' infrastructure-free approach sounds rather awesome."

Comments

good in theory, bad in practice

[X0563511]

How exactly is one expected to create these maps then? Every time something metallic or magnetic is moved in the vicinity the previous map is now invalid.

Re:good in theory, bad in practice

[DeeEff]

It is simple. We build our malls out of plastic and we'll navigate just fine.

Another plus is that you'll be able to use this to find your kid in the ball pit at McDonalds next time they disappear.

Re:good in theory, bad in practice

[John Hasler]

Especially after pranksters start leaving magnets in random places...

Re:good in theory, bad in practice

[Gadget_Guy]

I assume that nobody here has actually used this system, so surely we can only say that theoretically it is bad in practice. In practice, they may have accounted for these problems in their theory.

My guess is that their software would not assume that people are lurching tens of meters in a single moment just because they pass something magnetic. They would use the same smoothing algorithm that GPS mapping uses. Have you ever noticed when you first load up a map on your GPS position is often quite inaccurate initially before eventually pin-pointing your location a few seconds later. They smooth out any anomalous readings after this, which you can see when your position briefly pauses while you are moving at a constant speed. During those pauses, the system has received new location that differs significantly from the last reading. These are obviously ignored to give the illusion of accuracy.

This magnetic system could do the same. With bidirectional communication, the software could report back anomalies due to changed environments and incorporate them into the self-correcting maps. Given that shopping centers do want to track their shoppers, it seems quite likely that there would be bidirectional communication happening.

Re:Compass

[X0563511]

It's called reading. It's been in use for like 1000 years.

(read the summary at least, please? this is doing far more than telling you your orientation.)

Re:Smartphone compass sensitive enough

[X0563511]

My phone (HTC EVO 3D) has a compass, accelerometer, gyro, and flux sensors. It's sensitive to changes as small as a single microtesla that I can tell, though noise usually means your sample resolution is about 5, instead. Some filtering would probably do nicely, since I'm only able to look at the raw reading.

BS meter pegged

[frovingslosh]

There is just no way that one would get enough information from a magnetometer to give you the information to do this, any more than a compass in the great outdoors can tell you where you are, it can only tell you headings. Of course, there are all of the other issues that people bring up also, like metal or electrical things moving in the area and changing (effectively randomizing) the minimal information that you have. But to focus on that only ignores the greater problem, any simple vector from a magnetometer (even if it included a vector strength) can't tell you a location in 2D or 3D space. And unless you somehow magically know the correct way to orient your magnetometer when you are holding it, then just moving it as you move through the structure could give you any magnetometer direction at any point.

Re:Smartphone compass sensitive enough

[vlm]

Bored? Grab your phone and run the app "GPS status" or probably a million similar apps, maybe even some free ones. Then move stuff around on your desk to see how the field changes. I can vary it about 20% by waving my steel clipboard around the phone. Now its possible with enough filtering you can assume changes are solely due to movement rather than me trying to sabotage the data gathering, and perhaps the map is actually of the 1st (or 2nd?) derivative of the field around my desk rather than just mapping the raw data so it doesn't matter if I'm IronMan and you're not, or if our phones do not have absolute calibration.

If I had more time on my hands I'd throw a fridge magnet on the floor, and try to "find the titanic" using the magnetometer and some string and graph paper and walking a grid pattern, or maybe pulling my phone along the floor on the grid pattern. Very much like the movie, I'll probably get bored halfway thru this titanic experiment. But it would probably work. Someone out there in /. land oughta try this, maybe try a big chunk of ferrous metal too, like a manhole cover (try not to get run over...)