Tracking in Locations Where GPS Does Not Work

"One idea that seemed worth pursuing was to use dead reckoning aided by an inertial gyroscope. Gyroscopes are essentially wheels mounted so that they can spin about an axis in any direction. Once a gyroscope begins spinning it tends to resist any change in the orientation of its spin axis. This makes it particularly useful in ship stabilizers to counteract rolling. Gyroscopes also lie at the heart of most automatic steering systems, like those used in airplanes, missiles and torpedoes.

But as the basis for a piece of emergency responder gear, expense and size were a major concern. And it seems that relatively inexpensive gyroscopes can be subject to a lot of drift, Fisher says. Positional errors can add up rapidly. That's a critical problem when trying to track a firefighter in a dark, smoke-filled building...

Whittaker suggested using a micro electro-mechanical systems (MEMS) type of gyroscope. MEMS are mechanical devices built onto semiconductor chips. They are small enough to be measured in micrometers and are used to make pressure, temperature, chemical and vibration sensors, light reflectors and switches as well as accelerometers for automobile airbags, vehicle control, pacemakers and games. Newer accelerometers use a heated gas bubble with thermal sensors. They operate much like the air bubble in a construction level. When the accelerometer is tilted or accelerated, sensors pick up the location of the gas bubble.

NPPTL liked the idea and awarded Carnegie Mellon an initial $100,000 contract to mock up a device in 2002. "It was a nice demonstration but inaccurate," Fisher recalls. A follow-on contract worth $250,000 was awarded for second and third-generation prototypes...

The prototype’s most recent demonstration took place January 20 in Pittsburgh and went "extremely well," Fisher says. During the demonstration a team of two "emergency responders" were able to simultaneously report their position, status and current course of actions to a base station. Also demonstrated was a personal data assistant-based multi-port display. This allowed several people to view the tracking and mapping. And the Carnegie Mellon team also demonstrated a remote viewing capability for the commander's base station. This enabled the tracking and mapping results to be projected onto a large screen for audience viewing.

Another prototype demonstration is set for March. After that, the NPPTL will decide whether or not to commit up to $1 million on field-testing the technology.

If it proves viable, the technology could help protect the lives of people like miners and emergency first responders."

From this directionsmag article.