The rise of readily available GPS-enabled devices was supposed to make losing one’s way a relic of a bygone era. But while GPS has undoubtedly changed the way we get around, it’s still imperfect – anywhere the satellite signal can’t reach might as well not be on the digital map because we can’t locate ourselves there. But researchers at NC State and Carnegie Mellon Universities may just have a solution. All they need to do is put radar in your shoe.
Thus far, the most common fix for GPS dead zones is to employ some kind of inertial measurement unit (IMU) that uses measures your speed and direction and figures your position relative to your last known GPS location. But IMUs can be faulty. Even a tiny error in measuring speed or direction will accumulate over time, so the longer you are without GPS the more inaccurate the IMU estimation. This can lead to serious problems if, say, you are trying to find your way out of a subterranean cave or a Wal Mart.These IMU errors are usually the result of misreading when the subject is standing still. The person may stop, but the IMU may think the person has taken a few more steps, or is even still moving slowly. So the NC State – CMU team devised a means for IMUs to better calculate when a person is standing still: a radar embedded in the heel of the shoe.
The shoe radar works by tracking the distance between the foot and the ground. If that distance doesn’t change for a given period of time, the system knows the foot is firmly planted and tells the IMU as much. By improving the IMUs understanding of when a person is at a complete standstill, the shoe radar can drastically reduce those accumulation errors.
Installing radar in every pair of shoes you own would probably be a bit over the top. But for people who spend a lot of time underground, especially in dangerous situations – miners come to mind, as do construction workers and engineers working on tunnels and large infrastructure projects – technology that can accurately locate you in a pinch seems like it would be a pretty wise investment.
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