Exploiting task regularities to transform between reference frames in robot teams

We describe a team of robots that uses a trail of landmarks to navigate between places of interest. The landmarks are not physical; they are waypoint coordinates generated online by each robot and shared with teammates over the network. Waypoints are specified with reference to features in the world that are relevant to the team's task and common to all robots. Using such task-level features as landmarks avoids the need to sense and name physical landmarks. Using these common landmarks, each robot can transform waypoint coordinates into its local reference frame, avoiding the cost of maintaining a fixed global coordinate system. The algorithm is tested in an experiment in which a team of 4 autonomous mobile robots run in our office building for more than 3 hours, travelling a total of 8.2 km (5.1 miles). Despite significant divergence of their local coordinate systems, they are able to share waypoints, forming and following a common trail between two fixed locations.