GPS-Free Tech Can Track Miners’ and Soldiers’ Boots Underground

A mining crew is trapped deep underground after a cave-in. Firefighters run into a smoke-spewing high-rise to battle a violent blaze. A team of soldiers breaches a door and storms into a dark building.
In any of these life-threatening scenarios, the direst question on the lips of rescuers or supervisors is, “Where are they right now?”  Dr. Alonzo Kelly, a professor at Carnegie Mellon University’s National Robotics Engineering Center, has a solution to answer that query. He and his team have figured a way to accurately locate people in places like buildings and mines where there is no GPS signal to help out.