To distill an accurate location from the jumble, WPI researchers have adopted algorithms used in two other detection technologies—synthetic aperture radar and computed tomography (CT) scanners—both of which develop images from multiple antennas or sensors. In the case of WPI’s application, an array of receivers, each about the size of a briefcase, would first have to be positioned around a structure when crews arrived at a scene. The WPI location tool is, however, “not ready for prime time,” developer James Duckworth says, noting that it must produce reliable data before it’s handed to firefighters, as even slightly inaccurate location data “can actually make a situation worse.”
A separate location tracking technology, however, is already being deployed. Developed by TRX Systems, it is called TRX Sentrix. This system also relies on a small unit carried by the user, but it starts with a known GPS-based location determined before entering a structure. Sensors inside the unit—including a gyroscope, accelerometer, and an altimeter—track movement from that point and transmit it to commanders.
When Security Management first wrote about this technology in October 2008 (See “A Burning Issue: How to Save Lives”), the developers were trying to find a way to mitigate errors that compounded as the sensor moved farther from its initial waypoint. Now, TRX CEO Carol Politi says that smarter sensors have solved the problem.
The new sensor software can detect specific types of motion based on accelerometer readings, such as walking, sidestepping, or crawling. Further, long-distance ranging can measure the distance between wearers or from base stations, Politi says. The company now offers a three-dimensional rendering interface that can “build” maps as users move through a structure, or can superimpose their movements in computerized building plans or in open-source exterior models like Google Maps.