Experimental analysis of slip ratio using the wheel walking locomotion mode in reconfigurable rovers

Planetary exploration has been affected by the ability of rovers to avoid getting trapped on sandy terrains. Currently, the European Space Agency in collaboration with the Russian Federal Space Agency are preparing the ExoMars mission, with the objective of placing a rover on the Martian surface to seek for signs of life. This rover is capable of a novel locomotion mode, commonly called wheel walking. It consists on moving the wheel forward and backward in order to improve traction and escape from terrains with a high slip ratio. The main drawback of this locomotion mode is related to the efficiency in power consumption. Therefore, it should be used only in extreme conditions. The objective of this paper is twofold. First, the definition of an experimental setup, based on a rover prototype, an experimental flat terrain and a mechanism to induce a given slip to the rover. Second, the use of this experimental scenario to validate a method, previously proposed by authors, to estimate the rover slip during the wheel walking locomotion mode.