Omnidirectional vision-based mapping by free region sweeping

This paper addresses the problem of systematic exploration of an unfamiliar environment to build a qualitative map by searching for recognizable targets. While exploring, a map is constructed which contains a set of regions of free space delineated by recognizable targets (landmarks) and the connectivity (adjacency and overlap) of these regions. As the robot moves along a trajectory while tracking a landmark, a region of free space is swept out. By representing a collection of free regions and their region-to-region connectivity as a graph, path planning amounts to graph search, and execution of the plan by a robot amounts to local movements to enter into the next free region. Both for exploration and for navigation, no metric information about the robot´s path nor absolute coordinates of its position or of landmark locations are required or recorded. After exploring, the robot produces a compact map which covers a large area, and provides information for fast self-localization and flexible path planning.