DIVERGENT STEREO IN AUTONOMOUS NAVIGATION - FROM BEES TO ROBOTS

This article presents some experiments of a real-time navigation syste m driven by two cameras pointing laterally to the navigation direction (Divergent Stereo). Similarly to what has been proposed in (Francesch ini et al. 1991; Coombs and Roberts 1992), our approach (Sandini et al . 1992; Santos-Victor et al. 1993) assumes that, for navigation purpos es, the driving information is not distance (as it is obtainable by a stereo setup) but motion and, more precisely, by the use of qualitativ e optical-flow information computed over nonoverlapping areas of the v isual field of two cameras. Following this idea, a mobile vehicle has been equipped with a pair of cameras looking laterally (much like hone ybees) and a controller based on fast, real-time computation of optica l flow has been implemented. The control of the mobile robot (Robee) i s based on the comparison between the apparent image velocity of the l eft and the right cameras. The solution adopted is derived from recent studies (Srinivasan 1991) describing the behavior of freely flying ho neybees and the mechanisms they use to perceive range. This qualitativ e information (no explicit measure of depth is performed) is used in m any experiments to show the robustness of the approach, and a detailed description of the control structure is presented to demonstrate the feasibility of the approach in driving the mobile robot within a clutt ered environment.A discussion about the potentialities of the approach and the implications in terms of sensor structure is also presented.