Jun 28, 2012 gps navigation
GPS works really well outdoors. Achieving same accuracy indoors however is not as easy.
Duke’s Pratt School of Engineering, funded by Google is working on a system where users can rely on their smartphones to locate their position in a covered environment. It is dubbed UnLoc. The idea behind it is analogous to how people use landmarks in outdoor environments. But they take advantage of invisible landmarks in indoor environments that your phone can sense. These could be distinct motion signatures created by elevators or stairwells, because the phone can detect motion, or certain dead spots where WiFi or 3G signals are absent.
Once such an invisible landmark is sensed, the phone can infer its current location, and then track its path from that point forward using motion sensors (such as accelerometers, compasses and gyroscopes). The tracking may become inaccurate over time, but as the phone hits other landmarks, it continuously corrects its location.
The application does not need any previous knowledge of the environment which is known as wardriving. It is a recursive application that gets better and better as it is used. It also requires less energy since it doesn’t rely on GPS signals to figure out your location. It’s been tested in a mall and it can achieve 1.6 meter accuracy.
The development of the UnLoc technique was supported by the National Science Foundation and Google.