Matt Shipman at The Abstract Blog reports on a Rube-Goldbergian invention for pedestrians:
Why You Would Put A Radar In Your Shoe
People rely on GPS devices to make sure they don’t get lost. But GPS devices rely on satellite connections, which are not always available…. But you can track your movements using an inertial measurement unit (IMU), which effectively tracks your acceleration to determine how far (and how quickly) you’ve moved…. Alas, IMUs have a flaw: they accumulate minor errors…. Here’s where the shoe radar comes in. The radar tracks the distance between your shoe and the ground…. The same navigation computer receives input from the IMU, and by “re-setting” your velocity to zero when you are standing still, eliminates much of the accumulated error from the IMU.
The Study: “A Low-Power Shoe-Embedded Radar for Aiding Pedestrian Inertial Navigation“, Chenming Zhou, J. Downey, D. Stancil and T. Mukherjee, IEEE Transactions on Microwave Theory and Techniques, vol. 58, no. 10, October 2010, pp. 2521 – 2528. (Thanks to Matt Shipman for bringing this to our attention.) The authors are at Carnegie Mellon University and at North Carolina State University.