Developers have recently created and marketed shoes with embedded GPS technology. Companies like GTX Corps have added the feature to everything from sneakers to work shoes, offering tracking capabilities to distance runners, parents of wandering teenagers and guardians of Alzheimer's patients. Now, researchers from North Carolina State University and Carnegie Mellon University have built onto this concept. According to Science Centric, researchers from the two schools have developed a "shoe-embedded radar system" to guide you on your way.
The article points out that when you are in a place where satellite connections are limited, GPS doesn't do you much good. According to the story, devices like inertial measurement units (IMUs) can be used with GPS. The IMUs track your acceleration and deceleration to figure out how far you have moved and at what speed. Then, it can calculate where you've gone since you lost your GPS signal to help you retrace your steps.
The story points out that IMU technology has traditionally had problems because tiny errors in calculation add up over time until the predictions are way off. This is where the shoe radar comes in. Science Centric quotes Dan Stancil, co-author of a paper describing the research, saying "to address this problem of accumulating acceleration error, [the researchers have] developed a prototype portable radar sensor that attaches to a shoe."
The radar tracks the distance from your heel to the ground and can tell when your foot is remaining still — either because the wearer is standing still or just in between steps for a microsecond. This motionlessness lets the computer reset to zero, so the accumulated errors can be reduced. In the end, the radar works with IMUs and GPS to help you (or your family) accurately track your location.