GPS is a godsend for people with absolutely no natural sense of direction. But sometimes, these people-tracking satellite systems don't work so well in a dense city, or worse--when you go anywhere indoors.
We've seen some indoor positioning systems that require you to wear an additional device or even use the Earth's magnetic field in conjunction with your phone's compass. DARPA, however, is developing an indoor GPS system that uses the same trusted, tested tech in your phone, except on a chip that's smaller than a penny.
DARPA calls its prototype chip a Timing and Inertial Measurement Unit (TIMU). Although the chip itself measures just 10 cubic millimeters in size, it's packed with three gyroscopes and three accelerometers, as well as an internal clock. Your smartphone also has these same sensors too; the major difference with this chip, though, is that each of these sensors are 50 micrometers thin (almost as thin as a human hair) stacked on top of each other, so it's a way smaller package.
The device is designed to start working as soon as you lose your regular GPS signal. From that starting point, the gyroscopes and accelerometers keep track of how far away you are--as well in which direction you have moved--from that initial point.
DARPA is developing the technology to help keep track of troops fighting in urban and indoor situations where satellite tracking may not work. Since the device is so small, we imagine that the TIMU could eventually end up inside our mobile devices because it's pretty easy to get lost indoors, too. I mean, have you ever been to a MegaMall?