Designing Mobile Robots for Physical Interaction with Sandy Terrains (IS Colloquium)

One day, robots will widely support exploration and development of unstructured natural environments. Much of the work I will present in this lecture is supported by NASA and is focused on robot design research relevant to accessing the surfaces of the Moon or Mars. Tensile elements appear repeatedly across the wide array of missions envisioned to support human or robotic exploration and habitation of the Moon. With a single secured tether either rovers or astronauts, or both, could belay down into steep lunar craters for the exploration of permanently shadowed regions; the tether prevents catastrophic slipping or falling and mitigates risk while we search for water resources. Like a tent that relies on tensioned ropes to sustain its structure, tensegrity-based antennae, dishes, and habitations can be made large and strong using very lightweight materials. We ask: Where does the tension in these lightweight systems go? Ultimately, these concepts will require anchors that attach cables autonomously, securely, and reliably to the surrounding regolith to react tensile forces. Thus, the development of new autonomous burrowing and anchoring technologies and modeling techniques to guide design and adoption is critical across multiple space relevant programs. Yet burrowing and anchoring problems are hard for multiple reasons, which remain fundamental areas of discovery. Our goal is to understand how the mechanics of granular and rocky interaction influences the design and control small-scale robotic systems for such forceful manipulations. I will present new mobility and anchoring strategies to enable small robots to resist, or "tug," massive loads in loose terrain, like regolith. The idea is that multiple tethered agents can work together to perform large-scale manipulations, even where traction and gravity is low. Resulting generalizable methods for rapidly modeling granular interactions also inform new mobility gaits to move over, through, or under loose sand more efficiently.