Remember the TV show Get Smart, about a bumbling detective and his cutting edge shoe phone?

The imaginary gadget didn't catch on in the real world. But shoes could some day come equipped with radar that works with GPS devices.

Say you're in a parking garage or in downtown Manhattan where tall buildings block your phone's GPS signal. Without clear access to signals sent from GPS satellites, your device is worthless and you end up getting lost.

Internal Measurement Unit

Unless, that is, you also have an internal measurement unit, or IMU, device a gadget that uses acceleration and deceleration to calculate how fast you're moving and in which direction.

Problem solved, right? When the GPS signal cuts out, you just switch on the IMU. It uses your last known GPS location to calculate where you are and where you need to go to get where you're going.

Problems With Location

But measuring movement is actually pretty tricky. Any small mistake in the measured acceleration results in position errors that grow with time.

So even if you're standing still and just rocking in place, a navigation computer relying solely on the IMU readings may show you wandering off in a random direction.

Creating Shoe Radar!

And that's where radar comes in. Engineers have developed a tiny radar sensor and navigation computer that attach to a shoe to keep track of the space between the shoe's heel and the ground.

Basically, the radar system helps the IMU device more accurately sense when you're moving and when you've stopped, which helps reduce navigation errors.

None of this technology is available in your local shoe store yet. But someday it could find its way there.