The Right Path: Comprehensive Path Planning for Lunar Exploration Rovers

This article presents a comprehensive path-planning method for lunar and planetary exploration rovers. In this method, two new elements are introduced as evaluation indices for path planning: 1) determined by the rover design and 2) derived from a target environment. These are defined as the rover´s internal and external elements, respectively. In this article, the rover´s locomotion mechanism and insolation (i.e., shadow) conditions were considered to be the two elements that ensure the rover´s safety and energy, and the influences of these elements on path planning were described. To examine the influence of the locomotion mechanism on path planning, experiments were performed using track and wheel mechanisms, and the motion behaviors were modeled. The planned paths of the tracked and wheeled rovers were then simulated based on their motion behaviors. The influence of the insolation condition was considered through path plan simulations conducted using various lunar latitudes and times. The simulation results showed that the internal element can be used as an evaluation index to plan a safe path that corresponds to the traveling performance of the rover´s locomotion mechanism. The path derived for the tracked rover was found to be straighter than that derived for the wheeled rover. The simulation results also showed that path planning using the external element as an additional index enhances the power generated by solar panels under various insolation conditions. This path-planning method was found to have a large impact on the amount of power generated in the morning/evening and at high-latitude regions relative to in the daytime and at low-latitude regions on the moon. These simulation results suggest the effectiveness of the proposed path-planning method.