Traversability index: a new concept for planetary rovers

A traversability index is introduced as a new and simple measure for traversability of planetary surfaces by mobile robots. This index is developed using the framework of fuzzy logic, and is expressed by linguistic fuzzy sets that quantify the suitability of the terrain for traversal based on its physical properties, such as slope and roughness. The traversability index is used for classifying planetary surfaces, and provides a simple means for incorporating the terrain quality data (out to about 10 metres) into the rover navigation strategy. A set of fuzzy navigation rules is developed using the traversability index to guide the rover toward the safest and the most traversable terrain. In addition, another set of fuzzy rules is developed to drive the rover from its initial position to a user-specified goal position. These two rule sets are integrated in a two-stage procedure for autonomous rover navigation without a priori knowledge about the environment. A computer simulation study is presented to demonstrate the capability of the rover to reach the goal safely while avoiding impassable terrains.