Abstract
The variety of illumination conditions in outdoor environments--in space or on earth--does not allow to use simple video cameras as a single perception means. A system composed of complementary sensors and sensitive to multiple frequencies is necessary when the system has to be efficient and reliable for any illumination and visibility conditions. On the other hand, geometrical information (edges, surfaces, etc.), which is extracted from usual perception systems, is not always sufficient to assure the safety of a navigation task. The physical properties of the surfaces such as the roughness and the dielectric constant (also related to the water content) represent interesting information since they allow to evaluate the navigability of the observed terrain: smooth surface, rugged surface, stones or soil, metallic surfaces, vegetation. etc. Unlike geometrical properties, these physical parameters are independent of the observation point and illumination conditions. Also, when associated to geometrical parameters, they should facilitate the location of a mobile vehicle by helping object recognition tasks. We defined a perception system based on the exploitation of theoretical perception models using fuzzy logic rules. This system should assure the perception of the scene for any illumination conditions and extract geometrical and physical surface properties. This new system should therefore enhance the navigation autonomy and reliability. We present the advantages of the developed approach and show the first testing results.
