Shape of things to comeDARPA looks for inertial-nav to be embedded in smart boot's heel

Published 14 May 2009

DARPA is funding the development of smart shoes: soldiers and first responders will be equipped with shoes with embedded inertial navigation sensor; sensor will help in keeping track of soldiers, special operatives, and first responders in harsh environments

Here is another push-the-envelope idea supported by DARPA: a highly accurate inertial navigation module which fits in the heel of a shoe. The agency has just awarded a contract to Bedford, Massachusetts-based Intersense to deliver, in collaboration with Case Western university, tiny yet highly accurate inertial-navigation units under a program called Micro Inertial Navigation Technology (MINT).

It is true that currently available GPS sat-nav tracking kits are so cheap and so small that they are installed in cell phone, but as Lewis Pages notes, they come with several drawbacks. They only work when they can receive signals from the satellites, which more often than not means having line-of-sight communication. Indoors, or even worse underground or underwater, sat-nav is not good.

There is also the question of accuracy. In general, current GPS kit able to pick up a decent number of satellites will still show errors in the region of five or ten meters. This may be good enough to tell you what road or motorway lane your car is in, what building you are standing outside of, and so on. It is not good enough to score a direct hit on a pickup truck or a shack using a smart weapon. This is why, in order the achieve a direct hit, smart bombs and missiles typically use a laser aiming dot or supplement their GPS with inertial navigation, terrain-matching radar, etc.

Page writes that there are ways to boost GPS accuracy to the one meter range, and it is hoped that both the upcoming Galileo Euro-sat-nav system and next-generation GPS will both offer such accuracy as standard. Note, though, that they still will not work indoors, underground, etc.

This inability to work indoors is a problem for DARPA and other projects it is sponsoring. The agency is sponsoring the development of small robots to be used for intelligence gathering inside buildings or under water. There is also the need to keep track of soldiers, special operatives, and first responders in such environments.

DARPA concluded that the best place to put an inertial nav sensors is on a soldier’s foot. The foot does not swivel about, wriggle, bend, or deviate from its course as much as the rest of the body. Also, it spends a good deal of its time stationary on the ground, making it easier to working out what is happening. DARPA’s MINT program therefore specifies that its desired micro-tracker units should fit “within the shoe sole.”

Intersense already have a boot-heel inertial unit, NavShoe, developed to help firemen or paramedics lost or trapped during disaster situations. It is not not very accurate, though. Now, with DARPA’s funds and a “high-resolution, error-correction ground reaction sensor cluster” from Case Western, this is about to change.