Mobility Mode Evaluation of a Wheel-on-Limb Rover on Glacial Ice Analogous to Europa Terrain

In this paper, we discuss the development of a multi-modal locomotion system and the results of field trials performed on fractured, glacial ice. Work was performed using the RoboSimian rover: a 32 degree-of-freedom, actively articulated mobility system. Three modes of mobility are compared: wheelrolling, inchworming (push-rolling) and wheel-walking. Each mobility mode is designed to operate with articulated suspension whereby the normal load per wheel, body orientation, and available limb workspace are actively controlled. Each mode is presented individually alongside a discussion of its performance on terrain of varied slope and topographic roughness. Further, the utility of a multi-modal approach is presented, whereby rover immobilization was avoided during field trials through the selection of appropriate mobility modes as a function of terrain properties. Lastly, the results of trials performed using a bodymounted sampling system and its ability to collect and process samples taken 10 cm beneath the surface are discussed.