Robot location using vision to recognize artificial landmarks

In this paper we propose a solution for the location of a mobile robot. The approach is based on visual sensing of artificial landmarks scattered across the workspace. The problem of location is divided in two stages: identification and positioning. The identification of the shape consists in its description in terms of statistical invariants, the comparison of these descriptors with known classes, and its assignation to the nearest pattern known. The positioning is solved in three steps: first, the transformation of the shape in the image plane is recovered using the change of the statistical moments; second, the 3D orientation of the landmark is inferred by calculating the parameters of the plane where the mark is; and finally, the position of the landmark with respect to the robot is computed. Through all the location process, the statistical moments is the underlying technique used. We present experimental evidence to analyze the error in the estimation of the 3D structure of some shapes for both a monocular and a two camera vision system. Our experiments show that the approach presented is suitable for robot location.