A unified framework for nearby and distant landmarks in bearing-only SLAM

Bearing-Only SLAM describes the process of simultaneously localizing a mobile robot while building a map of the unknown surroundings, using bearing measurements to landmarks as the only available exteroceptive sensor information. Commonly, the position of map features is estimated along with the robot pose. However, consistent initialization of these positions is a difficult problem in Bearing-Only SLAM, in particular for distant landmarks. In previous approaches, measurements to remote landmarks often had to be discarded, thus losing valuable orientation information. In this paper, we present for the first time a unifying framework allowing for non-delayed initialization of both nearby and distant features. This is made possible by a four-element landmark parametrization, combined with a constraint-based inferred measurement.