14 ms·

Startup uses disruption of Earth's magnetic field for indoor positioning

133 points by regandersong 14y ago

terhechte 14y ago
I really like this new approach to the positioning problem, especially since it doesn't require setting up wifi or shooting satellites into orbit. Does anyone know why this couldn't be used for outside positioning, much like GPS? Is the information not detailed enough, or do we lack good enough sensors to detect the fine-grained differences especially given all the electromagnetic noise that modern cities for example create. Edit: I just realized it's probably also because somebody would need to create a world-magnetic-field map, much like the street view cars driving all over the world.
- defrost 14y ago
  Which we have, not only is there a coarse scale global magnetic field model (two versions, in fact) there are detailed high resolution maps for large areas of the world (eg: all of Mali, all of Australia, most of Canada, much of the central 'stans) where mineral exploration has taken place. The positioning is complicated by the drift over time (there's a "new" global model every five years and for specific times & locations interpolation is performed) and fluctuates daily (as the Earth turns there's a diurnal pulsing in the induced magnetic field). This is where "a bit of signal processing" comes into play. The good news is the maths, the field testing, and the application of it is all a good 50 years old. Typical exploration mapping company: http://mcpharinternational.com/services/mining-exploration/aeromagnetics-magnetic-gradiometry http://mcpharinternational.com/services/mining-exploration/a... High resolution gridded geophysics for the Northern Territory, magnetics, gravity, radiometrics, etc: http://www.nt.gov.au/d/Minerals_Energy/Geoscience/index.cfm?header=Territory-wide%20and%20regional%20maps http://www.nt.gov.au/d/Minerals_Energy/Geoscience/index.cfm?...
  - terhechte 14y ago
    Thanks! Very interesting.
- pierrebouchet 14y ago
  There are solutions that do not need any pre-established magnetic field maps, because they simply derive velocity from local magnetic field disturbances and use magnometer measurements as an additional input for odometry calculations, using data fusion algorithms (e.g Kalman filtering). This allows to basically eliminate the drift induced by two successive integrations with low-cost IMUs. And with enough sensors (4 magnetometers) you can reconstruct 3D trajectory. The following thesis is fascinating and very instructive: http://pastel.archives-ouvertes.fr/docs/00/50/10/05/PDF/pdfVissiere.pdf http://pastel.archives-ouvertes.fr/docs/00/50/10/05/PDF/pdfV... Chapter 5 is very instructive, in particular the section Measuring magnetic fields gradients to derive velocity. Excerpts: If the body moves, then the sensed magnetic field must change according to Maxwell’s equations. If the magnetic measurements do not change significantly, then the solid body is not moving. This permits us to rule out velocity drifts in our estimation. Ultimately, this improves the position information obtained by integrating the velocity estimate. Note that they don't use the raw magnetic field, but its gradients, i.e a physical quantity that is intrinsequely local. Filtering out the earth's magnetic fields becomes quite easy (I suppose..) since these gradients are fast-varying quantities in comparison. Kind of like when you use an accelerometer: gravity is low-frequency, motions are high-frequency.
  - bhousel 14y ago
    Very interesting link... From 5.4.3, it actually looks like their magnetic positioning system works better in an indoor environment with lots of magnetic perturbations. I would not have expected that result, but thinking about it more it does make sense. They are estimating "where have I moved" using the local magnetic field, which is very different than how GPS works "where am I in relation to a fixed constellation".
AlexMuir 14y ago
I just don't see indoor navigation as a huge problem to be solved. And this seems a phenomenally complicated solution to a small problem. GPS works because outside is an enormous, unfamiliar place with tens of billions of destinations. Inside is small, relatively familiar, and even a large building has, at most, hundreds of destinations. Just watching the demo, it's super cool and super intelligent. But it doesn't look like it can do direction - it can only tell direction after you've walked a certain distance. How will it cope with large magnetic things that move - eg Forklift trucks, vehicles, trolleys, wire cages etc. I don't buy it. Ikea is the only potential place I could see this being of use, and there's no way anyone's going to bake in an extra sensor to a smartphone on the offchance. Look how slow adoption NFC has seen and that's a MASSIVE problem with multiple applications and a clear financial incentive.
- dangrossman 14y ago
  It uses the compass smartphones already have, not a new sensor.
  - dllthomas 14y ago
    You're not going to get gradient information off a single compass, are you?
- mike_esspe 14y ago
  I'd like to use some indoor navigation at large airports and subway. And it's a killer feature for exploring underground mines and caves, urban explorers will love it :)
- 21sappers 14y ago
  We build indoor navigation systems for hospitals in Canada and it is indeed a huge problem. The larger institutions are like a maze with wings and additions added over the course of decades. Making a route to your appointment though 3 buildings, up 2 elevators, and over a wing is easy. Helping you actually stay on the route as you follow it is not. If this new tech is cheaper to deploy than dozens, if not hundreds, of wifi beacons then it could be a real win.
sbanach 14y ago
I always thought a reasonable solution to this problem was triangulating via wifi and bluetooth signal strength from access points of known location. I tried it as a weekend project a few years ago but random fading was a killer and I never got it to work that well. Seems like it should be possible though. Are there good reasons not to do it this way?
- defrost 14y ago
  Not everywhere has wifi and bluetooth (yes, places exist outside of the wired world) and from the article it seems that an application area of interest is underground mining where transmitting radio through tunnels is already problematic.
cwiz 14y ago
Whoa :) This is very clever. I've been working on indoor positioning quite a long time already and might give this a try. No WiFi -> no extra WiFi hardware costs -> widespread use This technology might disrupt indoor advertisement.
PanMan 14y ago
How does this work? I understand if you know the true north and the magnetic north, you can get the difference, but I assume a compas only can measure one of them (the magnetic one). How do they determine the 'fault' in the signal with just 1 signal?
- flog 14y ago
  And what what if the stock is magnetic? ("Where's the fridge magnet isle?") ... and doesn't the earths magnetic fields change also? There's a number of questions I'd have about the stability of the data being collected and how quickly it'd go stale.
  - wpietri 14y ago
    Every phone using the app can contribute to your map data. If you combine magnetic data plus wifi data plus user behavior data, I expect you'd be able to continue to provide good 3D data to users. I'd bet the hard part is getting building owners to update things regularly. Who's going to remember to change the map when the grocery store moves the cereal from aisle 2 to aisle 7?
    - crisnoble 14y ago
      Maybe the maps could auto update using a combination of >magnetic data plus wifi data plus user behavior data
    - flog 14y ago
      You raise another point I haven't thought of: 3D. People are different heights... surely that changes the fields too. Interesting problems to be overcome.
- asmithmd1 14y ago
  It must require you to be moving in a straight line; otherwise you have just one parameter, the angle of the magnetic field, and there is no way for that one parameter to specify your location in 2 dimensional space.
dazbradbury 14y ago
What happens if there are large items which move and cause changes in the localised magnetic field readings? Things such as lifts, vehicles, regularly changing stock levels... Or are these all considered negligible?
- FrojoS 14y ago
  I have the exact same question. I use magnetometers with IMU's as part of my research and temporal disturbances of the magnetic field are a huge problem. Anyway, this new method sounds awesome. Thanks for posting!
- bhousel 14y ago
  Read the link in pierrebouchet's comment: http://news.ycombinator.com/item?id=4217838 http://news.ycombinator.com/item?id=4217838 From 5.4.3, it actually looks like this kind of magnetic positioning system works better in an indoor environment with lots of magnetic perturbations. This method measures where the person has moved, not where they currently are against a fixed constellation (like GPS). I'm guessing you would need to activate the data collection at a known waypoint (e.g. the front door of a business) and then it could track your movements around a magnetically perturbed space.
  - pvarangot 14y ago
    Those are stationary perturbations they are talking about, the ones they use to map the region. Your parent refers to moving perturbations, such as vehicles or electric motors. An underground mine is really really really different to a subway network if you are only looking at it magnetically.
- crisnoble 14y ago
  The demo in this video (https://www.youtube.com/watch?v=uoWs0c5TeTA&feature=player_embedded https://www.youtube.com/watch?v=uoWs0c5TeTA&feature=play...) seems to handle carts moving around pretty well.
lbotos 14y ago
I guess this would be a relatively relevant place to ask, does anyone know of an affordable technology that can be used for precision (inches) tracking of 8-36 items indoor or out? The caveat would be affordable. The use case would is BMX Racing. Scoring is still done by hand! I've looked into RFID tagging but the docs and manufacturer's specs are all over the place. Any ideas?
- jrockway 14y ago
  Computer vision seems like the logical solution to this problem.
  - lbotos 14y ago
    Too many variable and too much data processing to be used at a local level I'd think. Any specifics I should look into?
- 18pfsmt 14y ago
  Note: I will keep my comments to passive RFID (non-battery powered tags) and leave aside active RFID commonly used for toll roads, shipping containers, etc. RFID is actually a family of technologies, typically defined by ISO standards, and operating over several distinct frequencies: 134kHz (LF), 13.56MHz (HF), and 900MHz (UHF). LF and HF use inductive coupling between the tag (transponder) and reader (transceiver) while UHF uses capacitive coupling. Theses technologies do not allow one to know a specific distance, but rather when a tag is in the field or not. So, when Wal-Mart uses UHF tags on their pallets, they don't know where the pallet is exactly in their warehouse, they simply know when the pallet has passed through their loading dock. I've seen some triathlon timing systems use UHF RFID, but they still use cameras in case of close finishes. Hope that helps.
  - lbotos 14y ago
    Thanks! I've seen some timing systems that are used in triathlons but the main problem was making a field that was 25-30 feet width but a tight spread (1 foot). Do you think active would fair better in that respect? Last time I checked it seemed so but it also jacked up the price a bit. I know that for Olympic BMX they are using some type of active transponders but I can't think that any commercially available solution would be accurate enough. I assume they have to be doing camera checking too but for .000 second split times even a foot spread seems like a wide margin of error.
deepGem 14y ago
I did get an incidental 500 server error, guess the server is getting bombarded. Keep an eye folks.
deleted 14y ago
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darkstalker 14y ago
A cool use for this would be an app that tells you the position of merchandise inside a supermarket
Gring 14y ago
It apparently needs the user to move to get a position lock. This will not work well with the typical use case: user is in a shopping mall, needs to go to the bathroom, wonders where the closest one is and where he is, stops walking, opens his phone and starts the app. Expected outcome: the app says "toilets are 50 meters to the right". If the app now tells the user "I have no idea where you are. Please walk in a random direction in a straight line for 20 meters and I will try to find out, then tell you where you are and where the closest toilets are, which means that you might have walked in the wrong direction to begin with", the user is not really happy.
- a-priori 14y ago
  If this causes a negligible drain on the battery, then the device could passively record the magnetic field at all times into a circular buffer. When they ask where the toilets are, the device can check the recent data to immediately figure out where they are.
DanielBMarkham 14y ago
I have a small site dedicated to providing information about gps/cell phone tracking. As part of that, I've been doing a bit of reading about cell phone tracking capabilities. It amazes me that we are turning our phones into better tracking systems than we've ever used on wild animals. Whether it's sound fingerprinting, gps, WiFi tracking, or now magnetic disturbance tracking, your phone's location services is getting so it can tell within a few feet where you are at all times. (By 2016 FCC regulations make it a requirement that all phones locate themselves within 100m or so) This has amazing potential for startups. If your phone knows you are at the gym, it can start your workout routine. If you are at the library, it can decrease the ringer volume. Now with inter-building location ramping up, the opportunities will only increase. On a related note, this information can be requested by law enforcement without a warrant. Last year cell carriers handled over a million such requests. http://www.nytimes.com/2012/07/09/us/cell-carriers-see-uptick-in-requests-to-aid-surveillance.html?_r=1&hp http://www.nytimes.com/2012/07/09/us/cell-carriers-see-uptic... People wearing little electronic devices that allow law enforcement to determine their position and travel patterns over any period of time just by filling out a form and without a warrant. If you had told me 20 years ago this is where we'd be, I would have called you a paranoid nut-job.
- stcredzero 14y ago
  The kicker will be when they can do this, even when we've flipped the off switch. For now, there's always the off switch.
  - DanielBMarkham 14y ago
    One of the things I was curious about is whether the phone can be enabled remotely by the telco. I found conflicting information on the web. I suspect it can, but this is not something the carriers want to talk about. Just a suspicion, though. I imagine what happens 99% of the time is that the user doesn't want anything to do with tech like gps tracking, but then they find an app that does something cool, and it things like gps to be turned on in order for it to work. So in a way, just like Facebook is destroying privacy by "helping" folks share, many apps are destroying the anonymity of location and travel by "helping" folks with cool apps. That kinda sucks. Wish the situation were different. Note that location services comprises many different technologies, not all of which can be turned off. Many of them are required for the phone to operate. The upcoming FCC regs, for instance, require 100m self-locating ability to always be on. I guess for things like 911 service? Speaking of paranoia, there's also rumors that the FBI/black helicopter/MIB bunch can actually power-up your phone remotely, especially with some models. This sounds completely out-of-left-field to me, but who knows? Court docs show they can use your phone as a listening device even when you're not calling somebody, so I wouldn't put other things along these lines past them. There's probably a good reason Osama Bin Laden refused to have anybody associated with him possess a cell phone, whether it was used, had a battery in it, or not. Seems like I read something somewhere once about illuminating electronics gear with microwaves, then reading the signature of the radiation emitted. But it could have been in a pulp sci-fi novel. As I said, it's difficult to tell where reality ends and paranoia begins with this because reality is quickly catching up to the paranoia of just a few years ago. Who would have imagined sub-meter resolution on where you are? That's almost accurate enough to tell if you're wearing the phone in your jacket pocket or on your belt. Crazy stuff.
mmaunder 14y ago
If you're navigating on a boat, every boat has it's own deviation chart. When you then use the compass you factor in variation (what the chart says the difference is between mag north and true north) and the personalized deviation chart for that boat. To set this up, some guy comes down to the dock, takes your boat out, does a few 360's with known landmarks in site and compiles a table of how your boat's compass varies from standard magnetic north. Big things like the engine, generator, keel, etc will influence what your deviation chart looks like. Usually it's less than 4 degrees at each point of the compass IIRC. So every place in the world has metal objects that create that place's own distinct deviation from where magnetic north should be. So perhaps that's what these guys are using. A known table of variation and then looking at the deviation. What I wonder about is what happens when someone turns on a 12 amp vacuum cleaner, a monitor nearby goes into powersaving mode, someone moves their laptop or someone with their own cellphone walks past. These things emit magnetic fields, so I wonder how they've solved the problem of the local deviation changing constantly.
- famousactress 14y ago
  It's possible that constant change would be dealt with by probability and consensus. Compared to your best historical guesses at this location, how likely is it that the reading you're getting is accurate? You can establish high or low confidence and disregard sudden changes. Also, the more nodes (people, phones) you have the more you can build consensus between them, use the higher confidence predictions as waypoints for 'fixing' lower confidence ones.
- baddox 14y ago
  > What I wonder about is what happens when someone turns on a 12 amp vacuum cleaner, a monitor nearby goes into powersaving mode, someone moves their laptop or someone with their own cellphone walks past. These things emit magnetic fields, so I wonder how they've solved the problem of the local deviation changing constantly. Are any of those magnetic disturbances even within an order of magnitude of a smartphone's compass threshold? I'm surprised that the disturbance from a skyscraper's skeleton would be detectable, and a computer monitor seems like even more of a stretch.
Zenst 14y ago
Given that mobile phones have wires and electricity then they are creating small magnetic waves which will impact others. That all said this technolody is very suitable for underwater GPS were a GPS signal does not penetrate the water due to weakness and how bad radio travels thru water in general. So given that I would have to questions if the military don't already use something very similiar in submarines. Lets say I'd be very supprised if this was not being already utilised in some form or another in that feild.
torstesu 14y ago
Seems similar to the technology demonstrated in this article [1]. However, it does seem that IndoorAtlas Ltd had a better opportunity recognition radar. [1] http://www.newscientist.com/article/mg21328516.200-apps-glowing-arrows-guide-you-around-a-new-building.html http://www.newscientist.com/article/mg21328516.200-apps-glow...
- obtu 14y ago
  Another difference is that the use of a built-in compass eliminates the need for a badge.
harryf 14y ago
The demo of mapping inside the supermarket - real world Pacman...
deleted 14y ago
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zacharycohn 14y ago
The big problem/timesink here is mapping. Could this solved by combining the mapping process with the quadracopters that can autonomously fly through and map a building?
robomartin 14y ago
With reservations --simply because I don't know their details-- I'll say that this is nothing new at all and it could be the makings of another case of patent abuse. Local changes to the magnetic field have been used for quite some time for purposes such as oil exploration. I remember talking to an old geologist/oil man about twenty years ago as he went about locating candidate areas to explore based on these fluctuations. He explained that they'd use magnetometers to map out underground "cracks", deposits and other features. To go from that from generating local location data by overlaying a map of some sort (whether it is a building or something else) is nothing less than trivial. If you have any experience sailing you may have also witnessed the effect of large sunken metallic objects on the compass. Again, you could "navigate" by these effects "Hey we must be passing over the SS-Sunken Ship". Gotta love patents.
skyahead 14y ago
Does this need users to hold smartphones flat? If so, how inconvinient!

133 points by regandersong 14y ago

I really like this new approach to the positioning problem, especially since it doesn't require setting up wifi or shooting satellites into orbit. Does anyone know why this couldn't be used for outside positioning, much like GPS? Is the information not detailed enough, or do we lack good enough sensors to detect the fine-grained differences especially given all the electromagnetic noise that modern cities for example create. Edit: I just realized it's probably also because somebody would need to create a world-magnetic-field map, much like the street view cars driving all over the world.

defrost 14y ago
Which we have, not only is there a coarse scale global magnetic field model (two versions, in fact) there are detailed high resolution maps for large areas of the world (eg: all of Mali, all of Australia, most of Canada, much of the central 'stans) where mineral exploration has taken place. The positioning is complicated by the drift over time (there's a "new" global model every five years and for specific times & locations interpolation is performed) and fluctuates daily (as the Earth turns there's a diurnal pulsing in the induced magnetic field). This is where "a bit of signal processing" comes into play. The good news is the maths, the field testing, and the application of it is all a good 50 years old. Typical exploration mapping company: http://mcpharinternational.com/services/mining-exploration/aeromagnetics-magnetic-gradiometry http://mcpharinternational.com/services/mining-exploration/a... High resolution gridded geophysics for the Northern Territory, magnetics, gravity, radiometrics, etc: http://www.nt.gov.au/d/Minerals_Energy/Geoscience/index.cfm?header=Territory-wide%20and%20regional%20maps http://www.nt.gov.au/d/Minerals_Energy/Geoscience/index.cfm?...
- terhechte 14y ago
  Thanks! Very interesting.
pierrebouchet 14y ago
There are solutions that do not need any pre-established magnetic field maps, because they simply derive velocity from local magnetic field disturbances and use magnometer measurements as an additional input for odometry calculations, using data fusion algorithms (e.g Kalman filtering). This allows to basically eliminate the drift induced by two successive integrations with low-cost IMUs. And with enough sensors (4 magnetometers) you can reconstruct 3D trajectory. The following thesis is fascinating and very instructive: http://pastel.archives-ouvertes.fr/docs/00/50/10/05/PDF/pdfVissiere.pdf http://pastel.archives-ouvertes.fr/docs/00/50/10/05/PDF/pdfV... Chapter 5 is very instructive, in particular the section Measuring magnetic fields gradients to derive velocity. Excerpts: If the body moves, then the sensed magnetic field must change according to Maxwell’s equations. If the magnetic measurements do not change significantly, then the solid body is not moving. This permits us to rule out velocity drifts in our estimation. Ultimately, this improves the position information obtained by integrating the velocity estimate. Note that they don't use the raw magnetic field, but its gradients, i.e a physical quantity that is intrinsequely local. Filtering out the earth's magnetic fields becomes quite easy (I suppose..) since these gradients are fast-varying quantities in comparison. Kind of like when you use an accelerometer: gravity is low-frequency, motions are high-frequency.
- bhousel 14y ago
  Very interesting link... From 5.4.3, it actually looks like their magnetic positioning system works better in an indoor environment with lots of magnetic perturbations. I would not have expected that result, but thinking about it more it does make sense. They are estimating "where have I moved" using the local magnetic field, which is very different than how GPS works "where am I in relation to a fixed constellation".

AlexMuir 14y ago

I just don't see indoor navigation as a huge problem to be solved. And this seems a phenomenally complicated solution to a small problem. GPS works because outside is an enormous, unfamiliar place with tens of billions of destinations. Inside is small, relatively familiar, and even a large building has, at most, hundreds of destinations. Just watching the demo, it's super cool and super intelligent. But it doesn't look like it can do direction - it can only tell direction after you've walked a certain distance. How will it cope with large magnetic things that move - eg Forklift trucks, vehicles, trolleys, wire cages etc. I don't buy it. Ikea is the only potential place I could see this being of use, and there's no way anyone's going to bake in an extra sensor to a smartphone on the offchance. Look how slow adoption NFC has seen and that's a MASSIVE problem with multiple applications and a clear financial incentive.

dangrossman 14y ago
It uses the compass smartphones already have, not a new sensor.
- dllthomas 14y ago
  You're not going to get gradient information off a single compass, are you?
mike_esspe 14y ago
I'd like to use some indoor navigation at large airports and subway. And it's a killer feature for exploring underground mines and caves, urban explorers will love it :)
21sappers 14y ago
We build indoor navigation systems for hospitals in Canada and it is indeed a huge problem. The larger institutions are like a maze with wings and additions added over the course of decades. Making a route to your appointment though 3 buildings, up 2 elevators, and over a wing is easy. Helping you actually stay on the route as you follow it is not. If this new tech is cheaper to deploy than dozens, if not hundreds, of wifi beacons then it could be a real win.

sbanach 14y ago

I always thought a reasonable solution to this problem was triangulating via wifi and bluetooth signal strength from access points of known location. I tried it as a weekend project a few years ago but random fading was a killer and I never got it to work that well. Seems like it should be possible though. Are there good reasons not to do it this way?

defrost 14y ago
Not everywhere has wifi and bluetooth (yes, places exist outside of the wired world) and from the article it seems that an application area of interest is underground mining where transmitting radio through tunnels is already problematic.

cwiz 14y ago

Whoa :) This is very clever. I've been working on indoor positioning quite a long time already and might give this a try. No WiFi -> no extra WiFi hardware costs -> widespread use This technology might disrupt indoor advertisement.

PanMan 14y ago

How does this work? I understand if you know the true north and the magnetic north, you can get the difference, but I assume a compas only can measure one of them (the magnetic one). How do they determine the 'fault' in the signal with just 1 signal?

flog 14y ago
And what what if the stock is magnetic? ("Where's the fridge magnet isle?") ... and doesn't the earths magnetic fields change also? There's a number of questions I'd have about the stability of the data being collected and how quickly it'd go stale.
- wpietri 14y ago
  Every phone using the app can contribute to your map data. If you combine magnetic data plus wifi data plus user behavior data, I expect you'd be able to continue to provide good 3D data to users. I'd bet the hard part is getting building owners to update things regularly. Who's going to remember to change the map when the grocery store moves the cereal from aisle 2 to aisle 7?
  - crisnoble 14y ago
    Maybe the maps could auto update using a combination of >magnetic data plus wifi data plus user behavior data
  - flog 14y ago
    You raise another point I haven't thought of: 3D. People are different heights... surely that changes the fields too. Interesting problems to be overcome.
asmithmd1 14y ago
It must require you to be moving in a straight line; otherwise you have just one parameter, the angle of the magnetic field, and there is no way for that one parameter to specify your location in 2 dimensional space.

dazbradbury 14y ago

What happens if there are large items which move and cause changes in the localised magnetic field readings? Things such as lifts, vehicles, regularly changing stock levels... Or are these all considered negligible?

FrojoS 14y ago
I have the exact same question. I use magnetometers with IMU's as part of my research and temporal disturbances of the magnetic field are a huge problem. Anyway, this new method sounds awesome. Thanks for posting!
bhousel 14y ago
Read the link in pierrebouchet's comment: http://news.ycombinator.com/item?id=4217838 http://news.ycombinator.com/item?id=4217838 From 5.4.3, it actually looks like this kind of magnetic positioning system works better in an indoor environment with lots of magnetic perturbations. This method measures where the person has moved, not where they currently are against a fixed constellation (like GPS). I'm guessing you would need to activate the data collection at a known waypoint (e.g. the front door of a business) and then it could track your movements around a magnetically perturbed space.
- pvarangot 14y ago
  Those are stationary perturbations they are talking about, the ones they use to map the region. Your parent refers to moving perturbations, such as vehicles or electric motors. An underground mine is really really really different to a subway network if you are only looking at it magnetically.
crisnoble 14y ago
The demo in this video (https://www.youtube.com/watch?v=uoWs0c5TeTA&feature=player_embedded https://www.youtube.com/watch?v=uoWs0c5TeTA&feature=play...) seems to handle carts moving around pretty well.

lbotos 14y ago

I guess this would be a relatively relevant place to ask, does anyone know of an affordable technology that can be used for precision (inches) tracking of 8-36 items indoor or out? The caveat would be affordable. The use case would is BMX Racing. Scoring is still done by hand! I've looked into RFID tagging but the docs and manufacturer's specs are all over the place. Any ideas?

jrockway 14y ago
Computer vision seems like the logical solution to this problem.
- lbotos 14y ago
  Too many variable and too much data processing to be used at a local level I'd think. Any specifics I should look into?
18pfsmt 14y ago
Note: I will keep my comments to passive RFID (non-battery powered tags) and leave aside active RFID commonly used for toll roads, shipping containers, etc. RFID is actually a family of technologies, typically defined by ISO standards, and operating over several distinct frequencies: 134kHz (LF), 13.56MHz (HF), and 900MHz (UHF). LF and HF use inductive coupling between the tag (transponder) and reader (transceiver) while UHF uses capacitive coupling. Theses technologies do not allow one to know a specific distance, but rather when a tag is in the field or not. So, when Wal-Mart uses UHF tags on their pallets, they don't know where the pallet is exactly in their warehouse, they simply know when the pallet has passed through their loading dock. I've seen some triathlon timing systems use UHF RFID, but they still use cameras in case of close finishes. Hope that helps.
- lbotos 14y ago
  Thanks! I've seen some timing systems that are used in triathlons but the main problem was making a field that was 25-30 feet width but a tight spread (1 foot). Do you think active would fair better in that respect? Last time I checked it seemed so but it also jacked up the price a bit. I know that for Olympic BMX they are using some type of active transponders but I can't think that any commercially available solution would be accurate enough. I assume they have to be doing camera checking too but for .000 second split times even a foot spread seems like a wide margin of error.

deepGem 14y ago

I did get an incidental 500 server error, guess the server is getting bombarded. Keep an eye folks.

deleted 14y ago

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darkstalker 14y ago

A cool use for this would be an app that tells you the position of merchandise inside a supermarket

Gring 14y ago

It apparently needs the user to move to get a position lock. This will not work well with the typical use case: user is in a shopping mall, needs to go to the bathroom, wonders where the closest one is and where he is, stops walking, opens his phone and starts the app. Expected outcome: the app says "toilets are 50 meters to the right". If the app now tells the user "I have no idea where you are. Please walk in a random direction in a straight line for 20 meters and I will try to find out, then tell you where you are and where the closest toilets are, which means that you might have walked in the wrong direction to begin with", the user is not really happy.

a-priori 14y ago
If this causes a negligible drain on the battery, then the device could passively record the magnetic field at all times into a circular buffer. When they ask where the toilets are, the device can check the recent data to immediately figure out where they are.

DanielBMarkham 14y ago

I have a small site dedicated to providing information about gps/cell phone tracking. As part of that, I've been doing a bit of reading about cell phone tracking capabilities. It amazes me that we are turning our phones into better tracking systems than we've ever used on wild animals. Whether it's sound fingerprinting, gps, WiFi tracking, or now magnetic disturbance tracking, your phone's location services is getting so it can tell within a few feet where you are at all times. (By 2016 FCC regulations make it a requirement that all phones locate themselves within 100m or so) This has amazing potential for startups. If your phone knows you are at the gym, it can start your workout routine. If you are at the library, it can decrease the ringer volume. Now with inter-building location ramping up, the opportunities will only increase. On a related note, this information can be requested by law enforcement without a warrant. Last year cell carriers handled over a million such requests. http://www.nytimes.com/2012/07/09/us/cell-carriers-see-uptick-in-requests-to-aid-surveillance.html?_r=1&hp http://www.nytimes.com/2012/07/09/us/cell-carriers-see-uptic... People wearing little electronic devices that allow law enforcement to determine their position and travel patterns over any period of time just by filling out a form and without a warrant. If you had told me 20 years ago this is where we'd be, I would have called you a paranoid nut-job.

stcredzero 14y ago
The kicker will be when they can do this, even when we've flipped the off switch. For now, there's always the off switch.
- DanielBMarkham 14y ago
  One of the things I was curious about is whether the phone can be enabled remotely by the telco. I found conflicting information on the web. I suspect it can, but this is not something the carriers want to talk about. Just a suspicion, though. I imagine what happens 99% of the time is that the user doesn't want anything to do with tech like gps tracking, but then they find an app that does something cool, and it things like gps to be turned on in order for it to work. So in a way, just like Facebook is destroying privacy by "helping" folks share, many apps are destroying the anonymity of location and travel by "helping" folks with cool apps. That kinda sucks. Wish the situation were different. Note that location services comprises many different technologies, not all of which can be turned off. Many of them are required for the phone to operate. The upcoming FCC regs, for instance, require 100m self-locating ability to always be on. I guess for things like 911 service? Speaking of paranoia, there's also rumors that the FBI/black helicopter/MIB bunch can actually power-up your phone remotely, especially with some models. This sounds completely out-of-left-field to me, but who knows? Court docs show they can use your phone as a listening device even when you're not calling somebody, so I wouldn't put other things along these lines past them. There's probably a good reason Osama Bin Laden refused to have anybody associated with him possess a cell phone, whether it was used, had a battery in it, or not. Seems like I read something somewhere once about illuminating electronics gear with microwaves, then reading the signature of the radiation emitted. But it could have been in a pulp sci-fi novel. As I said, it's difficult to tell where reality ends and paranoia begins with this because reality is quickly catching up to the paranoia of just a few years ago. Who would have imagined sub-meter resolution on where you are? That's almost accurate enough to tell if you're wearing the phone in your jacket pocket or on your belt. Crazy stuff.

mmaunder 14y ago

If you're navigating on a boat, every boat has it's own deviation chart. When you then use the compass you factor in variation (what the chart says the difference is between mag north and true north) and the personalized deviation chart for that boat. To set this up, some guy comes down to the dock, takes your boat out, does a few 360's with known landmarks in site and compiles a table of how your boat's compass varies from standard magnetic north. Big things like the engine, generator, keel, etc will influence what your deviation chart looks like. Usually it's less than 4 degrees at each point of the compass IIRC. So every place in the world has metal objects that create that place's own distinct deviation from where magnetic north should be. So perhaps that's what these guys are using. A known table of variation and then looking at the deviation. What I wonder about is what happens when someone turns on a 12 amp vacuum cleaner, a monitor nearby goes into powersaving mode, someone moves their laptop or someone with their own cellphone walks past. These things emit magnetic fields, so I wonder how they've solved the problem of the local deviation changing constantly.

famousactress 14y ago
It's possible that constant change would be dealt with by probability and consensus. Compared to your best historical guesses at this location, how likely is it that the reading you're getting is accurate? You can establish high or low confidence and disregard sudden changes. Also, the more nodes (people, phones) you have the more you can build consensus between them, use the higher confidence predictions as waypoints for 'fixing' lower confidence ones.
baddox 14y ago
> What I wonder about is what happens when someone turns on a 12 amp vacuum cleaner, a monitor nearby goes into powersaving mode, someone moves their laptop or someone with their own cellphone walks past. These things emit magnetic fields, so I wonder how they've solved the problem of the local deviation changing constantly. Are any of those magnetic disturbances even within an order of magnitude of a smartphone's compass threshold? I'm surprised that the disturbance from a skyscraper's skeleton would be detectable, and a computer monitor seems like even more of a stretch.

Zenst 14y ago

Given that mobile phones have wires and electricity then they are creating small magnetic waves which will impact others. That all said this technolody is very suitable for underwater GPS were a GPS signal does not penetrate the water due to weakness and how bad radio travels thru water in general. So given that I would have to questions if the military don't already use something very similiar in submarines. Lets say I'd be very supprised if this was not being already utilised in some form or another in that feild.

torstesu 14y ago

Seems similar to the technology demonstrated in this article [1]. However, it does seem that IndoorAtlas Ltd had a better opportunity recognition radar. [1] http://www.newscientist.com/article/mg21328516.200-apps-glowing-arrows-guide-you-around-a-new-building.html http://www.newscientist.com/article/mg21328516.200-apps-glow...

obtu 14y ago
Another difference is that the use of a built-in compass eliminates the need for a badge.

harryf 14y ago

The demo of mapping inside the supermarket - real world Pacman...

deleted 14y ago

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zacharycohn 14y ago

The big problem/timesink here is mapping. Could this solved by combining the mapping process with the quadracopters that can autonomously fly through and map a building?

robomartin 14y ago

With reservations --simply because I don't know their details-- I'll say that this is nothing new at all and it could be the makings of another case of patent abuse. Local changes to the magnetic field have been used for quite some time for purposes such as oil exploration. I remember talking to an old geologist/oil man about twenty years ago as he went about locating candidate areas to explore based on these fluctuations. He explained that they'd use magnetometers to map out underground "cracks", deposits and other features. To go from that from generating local location data by overlaying a map of some sort (whether it is a building or something else) is nothing less than trivial. If you have any experience sailing you may have also witnessed the effect of large sunken metallic objects on the compass. Again, you could "navigate" by these effects "Hey we must be passing over the SS-Sunken Ship". Gotta love patents.

skyahead 14y ago

Does this need users to hold smartphones flat? If so, how inconvinient!