Rule-based traversability indices for multi-scale terrain assessment

This paper presents novel measures of terrain traversability at three different scales of resolution; namely Local, Regional, and Global Traversability Indices. The Local Traversability Index is related by a set of linguistic rules to local obstacles and surface softness, measured by on-board sensors mounted on the robot. The rule-based Regional Traversability Index is computed from the terrain roughness and slope that are extracted from video images obtained by on-board cameras. The Global Traversability Index is obtained from the terrain topographic map, and is based on the natural or man-made surface features such as mountains and craters. Each traversability index is represented by four fuzzy sets with the linguistic labels {POOR, LOW, MODERATE, HIGH}, corresponding to surfaces that are unsafe, moderately-unsafe, moderately-safe, or safe for traversal, respectively(1).