Stereo Driving and Position Estimation for Autonomous Planetary Rovers

In this paper we present two new approaches to planetary rover perception. One approach concerns stereo driving without 3-D reconstruction. This approach begins with weakly calibrated stereo images, and evaluates the traversability of terrain using shape indicators such as relative slope and relative elevation. The approach then evaluates candidate paths based on the traversability analysis and generates the best path. The second approach involves estimating vehicle position by observing the Sun. At a given time, a measurement of the Sun's altitude constrains the observer to lie on a circle on the terrestrial surface called the circle of equal altitude. We determine the position of the observer by intersecting circles of equal altitude identified at different times. We are validating experimentally both approaches in unstructured, outdoor environments with several wheeled rovers, Future efforts will transfer the developed technology into Lunar Rover demonstration and flight programs.