In this paper, we have presented 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 computes new driving commands for the vehicle based on the path evaluations.
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.
To date, we have developed these approaches enough to be confident of their feasibility, and to be convinced of their potential effectiveness. However, considerable effort is still required to achieve the levels of technical maturity and generality required for Lunar Rover demonstration and flight programs.
Future work on stereo driving will concentrate on extensive testing on robot vehicles, and refinements based on this experience. Our goal is a fully automated system operating with uncalibrated stereo cameras demonstrated on several platforms.
Future work on sun tracking will concentrate on achieving altitude measurement accuracies better than 0.1 degree. This will require design of a highly stable camera platform, and use of a high precision digital inclinometer.