Inertial tracking. Historically, inertial tracking systems have been used by the military to track missiles in flight and by NASA to track satellites orbiting in outer space. Such systems use inertial sensors, such as accelerometers, which measure acceleration in a linear direction, and gyros, which measure an object’s rate of turn, to predict and track an object’s trajectory through space.
Humans, of course, are not instruments designed through mathematical models that follow a programmable path. They follow random, unpredictable paths.
“We’re trying to figure out where they are going on little information,” Teolis says. “We can’t predict where they are going to go based on where they went last.”
Complicating the issue is the fact that inertial tracking systems accumulate errors pretty quickly. It also doesn’t help that TRX’s tracking system uses less sophisticated inertial sensors, which are more error prone. Those sensors are used because they are less expensive. If the company didn’t opt for that approach, no fire department could afford the finished product, explains Teolis.
But the company found a cost-effective way around the problem by tweaking the algorithm used by the inertial sensors to pinpoint a destination. How did they do it? “Our secret,” she says.
That solution addresses only one-half of the problem, however. Even if TRX’s system can track firefighters’ movements through a structure, that data must be able to get through the interference of modern buildings. That’s where mesh networking comes in.
Mesh networking. By connecting each firefighter’s wireless radio to the others, TRX creates a wireless network that is synched to a base station outside. The system is designed to send the tracking information through the network until it finds a firefighter’s radio that can transmit the information outside the structure.
During recent tests in Silver Spring, Maryland, TRX had four people hooked up to the tracking system walk around an 18-story building randomly. “Ninety-five percent of the time, we could get the data out,” she says.
Design and function. TRX’s Sentinel Tracking System has two main components: a tracking module and a communications module. The tracking module, which must be worn around the firefighter’s waist, uses the inertial sensors to calculate where a firefighter is within a structure and relays the information to the communications module.
The communications module uses the wireless radio to communicate with the base station, even from miles away. It can be worn anywhere on the firefighter’s body. Firefighters in danger also have the ability to press a red distress button, which transmits an immediate alarm to the base station.
From the base station, ideally a durable laptop mounted in a fire engine, an incident commander would track his firefighters as they made their way through a structure. On the interface, the firefighters tracked on screen resemble tiny pellets from a Pac-Man game.
TRX Systems’ engineers were originally developing the program with the idea that building plans for any building being responded to would be input so that the software could plot the firefighters’ trajectory throughout the floor plan. But the system’s developers learned that fire departments don’t usually have access to a building’s floor plans.
This realization led the company to build in “smart algorithms” that can build a floor plan as firefighters progress through a building. “The importance of that is when you’re trying to go in and find somebody,” says Teolis, “you want to know where they are relative to the structure of the building.”
In addition to tracking movement, the system can also track firefighters’ vitals. The program has been designed to allow add-ons, such as off-the-shelf heart-rate monitors so that the incident commander can monitor the health of his men in real time, says Teolis.
The idea is to eventually be able to detect firefighters showing signs of distress and to rescue them before they’re actually in danger, she explains.
The system allows information to be distributed to as many command posts as needed. Edwards of MFRI sees revolutionary potential in the new technology. He recounted a day more than 16 years ago when he was chief of Prince George’s County, Maryland, Fire Department. In that case, firefighter Kenneth Hendricks rescued a child from a one-story house, then returned for another run-through. Searching the basement of the house, Hendricks became trapped. No one knew he was down there. By the time his comrades found him, he was dead.
Edwards says that if TRX’s system existed then, Hendricks likely would be alive today. “It would have immediately indicated that he was in trouble, and it would have immediately indicated where he was,” he says.
In April, TRX Systems and the MFRI team demonstrated the system at the 2008 Metropolitan Fire Chiefs Conference and received a positive reception from attendees, says Edwards.
Chief Dennis Rubin of the District of Columbia Fire Department also got a look at the system during a live demonstration at a training seminar at MFRI a few months ago.
“This new system offers a higher degree of accuracy [than previous prototypes],” says Rubin, “and offers an easier application to know who is at the incident, where they are in the incident, what they are doing in the incident, and under what conditions.”
Other demonstrations have consisted of tests at MFRI, in the 18-story building in Silver Spring, and on the campus of the University of Maryland, College Park, says Edwards. Some of these have been under fire conditions.
TRX Systems and MFRI are planning to launch a pilot program with the fire departments of Prince George’s and Montgomery counties in Maryland as well as with the District of Columbia fire department before the end of the year. The firefighter tracking system will be given to one station per fire department, says Edwards.
The tests will allow firefighters to use and evaluate the system under nonemergency conditions. Their comments and criticisms of the system will then be fed back into the development process to perfect the system.