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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."
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.
For large sets, this will be our guide even unto death, for the LORD will work for each type of data it is applied to...
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.)
For large sets, this will be our guide even unto death, for the LORD will work for each type of data it is applied to...
Basic compass navigation has two data points: North and South. This has millions. It uses a compass, true, but it uses a sophisticated vector map of magnetic fields which normal compass navigation does not.
"None can love freedom heartily, but good men; the rest love not freedom, but license." --John Milton
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.
For large sets, this will be our guide even unto death, for the LORD will work for each type of data it is applied to...
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.
I'm an American. I love this country and the freedoms that we used to have.
...so malls are going to problematic, no? Airports? Supermarkets? Retail stores that aren't going under...?
Lol.
Perhaps they have methods for mitigating these things or they are less problematic than I expect, but just changing the shelving and orientation in a store would screw this thing up, doesn't it seem?
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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...)
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
Reliable indoor positioning is probably one of the key pre-requisites to building workable augmented-reality apps like games and such. There's probably a real payoff for the long term, but maybe not for the group that invents the underlying concepts/tech, unless they find some way to see it through to applications.
...the basement. You are likely to be eaten by a grue.
systemd is Roko's Basilisk.
Make a pair of big coils, put some power through it, and you can make a big electromagnetic field. Depending on how you connect the coils, the magnetic field will have interesting properties. With simple electronics, you can vary the field strength between your coils.
my phone has a couple of gyroscopes. is the error from these so bad that it can't keep track of my position while i'm inside a mall? if so, why is it there at all?