Tools to determine exact location when using ibeacons

Question

We are working with a Retail client who would like to know if using multiple iBeacons throughout the store would help track a customer\'s exact location when they are inside the

Answer 1

Bluetooth Low Energy (4.0) alone is not a robust indoor location and mapping technology, it will most likely become part of the fabric of indoor location technologies, in much the same way wi-fi signals are used to add fidelity to GPS signals in cities. Currently iBeacon can really only be used for fairly nebulous nodes indoors, like 'the shoe department' (assuming a large store)

I expect via the 'iBeacon' service (or something alternatively-named), Apple are working on high-resolution indoor location for app developers. You need look no further than their purchase of WifiSLAM, in mid 2013, for evidence. As yet, iBeacon and any other solely BLE technology is not going to give you precise indoor location. (Perhaps if you blanket the store with beacons, and combine a probabilistic model with a physical model, you could do it, but not with any practically-implementable beacon strategy.)

Also of note, is the discussion around Nokia's next-gen BLE HAIP (High-Accuracy Indoor Positioning) version http://conversations.nokia.com/2012/08/23/new-alliance-helps-you-find-needle-in-a-haystack/

Basically accurate indoor positioning doesn't exist in the wild yet, but it's about to...

Answer 2

The above problem can be solved using technology that combines Wi-Fi trilateration and a phone's sensor data. We get 1 meter accuracy in spaces that are properly outfitted when companies integrate our SDK with their app. The accuracy of these methods has improved dramatically over the last year.

Answer 3

The solution is a technique called trilateration. There is a decent wiki article on it.

If you assume that all the beacons and the receiver are on the same plane you can ignore the Z dimension and it simplifies to circles.

The math is still kind of messy. You'd have to do some matrix math on the positions of the beacons to shift one beacon to the origin and put a second beacon on the x axis, and then apply the inverse of your matrix to the result to convert it back to "real" coordinates.

The big problem is that the "accuracy" (aka distance) value is anything but accurate. Even in a wide open space with no interference, the distance signals vary quite a bit. Add any interference (like from your body holding the phone even) and it gets worse. Add walls, furniture, metal surfaces, other people, etc, and it gets really wonky.

I have it on my list of things to do to write trilateration code, measure out a grid in my yard (when the weather warms up), take a tape measure, and do some testing.

Answer 4

I have not done the extensive research that I believe went into Phil's above master's thesis, but...

There is another team that has claimed to have figured this out using various AI algorithms . See this linkedin post: https://www.linkedin.com/groups/6510475/6510475-5866674142035607552

As someone who develops beacons ( http://www.getgelo.com ) I can share first hand that pretty much any object will drastically change the consistency and accuracy of the RSSI which is going to make computing an exact position impossible. (Phil, I hope you prove me wrong, I haven't read your thesis yet).

If are the only person in a wide open space that has a grid of beacons then you can likely get this to work, but as soon as you add other people, walls, objects, etc, then you're SOL.

You can approximate location which is what iBeacons do and are pretty bad at, but it's directionless.

You could deploy enough beacons so that essentially wherever you are in a retail location you're standing very close to a beacon and you can have high confidence that you're in aisle 5 about 20 ft done (as opposed to being on the other side of aisle, aisle 6, and 20 ft down). Cost may become an issue here.

There are teams that are combining BLE with Wifi and other technologies to create a more accurate indoor positioning solution.

In short, and this will come as an echo of what's already been posted, BLE is not a good technology to be used solely for extremely accurate positioning.

Answer 5

Certainly if you can measure the exact position(lat/lon) of any individual iBeacon - that could be included in the beacons message. But assuming a stationary location - obviously this only need to be done once. Sort of an independent "calibration" exercise - which could itself be automated.

Answer 6

To determine the user's position based on surrounding iBeacons, which have to stay at fixed positions, it is possible by signal strength triangulation. Take a look at this thesis about Bluetooth Indoor Positioning ;-)