GPS Resolution in Denied Locations (GRIDLOC)

Latin American gangs exploit illegal border crossings to expand their sphere of influence in the United States. More than a hundred clandestine tunnels have been discovered beneath the US-Mexico border since 1990, and these tunnels are instrumental for drug smuggling and human trafficking. Clandestine tunnel detection has rapidly become a focus for the DHS, and the DHS is searching for methods to explore and map these tunnels remotely. GPS-equipped robots have been proposed for this use. However, GPS is currently accurate to only three meters at most, which is typically much greater than the tunnel diameter. Moreover, the GPS accuracy is further diminished underground, assuming that the GPS signal is even able to reach the receiver underground. Because many of these tunnels pass under private property, transmitting GPS signals via an embedded subterranean infrastructure is not an option.  Infoscitex (IST) proposes GPS Resolution in Denied Locations (GRIDLOC), which combines wide-area-augmented GPS with accelerometer-based position estimation and a novel IST-proprietary biomimetic orientation tracker (BOT). GRIDLOC is not subject to angular drift or magnetic interference, and therefore produces significantly reduced sine error and dead-reckoning error when used with a three-axis accelerometer in a position estimation system.