In the future, when machines run our lives, we'll need a way to keep tabs on all those helper bots. Two Wayne State University researchers have come up with a solution. In a paper titled "LOBOT: Low-Cost, Self-Contained Localization of Small-Sized Ground Robotic Vehicles," computer scientists Guoxing Zhan and Weisong Shi lay out a technique for ground robots to share location information. First, a robot minion has to figure out where it is. To accomplish this, the LOBOT system uses a GPS receiver, a 3-axis accelerometer, a magnetic field sensor, and multiple motor rotation sensors. Because the GPS sensor is extremely energy-intensive, it only infrequently checks the absolute position of the machine. The magnetic field sensors, accelerometer, and motor rotation sensors keep the location information up-to-date by helping to calculate the robot's change in position relative to its previously determined GPS location. Together, these processes give a good approximation of the robot's absolute location.

http://www.popsci.com/technology/article/2013-05/how-will-we-keep-track-robot-minions
http://roboticstomorrow.com/news/2013/05/16/lobot-technique-provides-accurate-real-time-3-d-positions-for-robotic-vehicles/21760
http://www.spacedaily.com/reports/Wayne_State_University_researchers_technique_helps_robotic_vehicles_find_their_way_help_humans_999.html