1. Gravity-Independent Locomotion: Potential Approaches to Robotic Mobility on Asteroid Surfaces Eddie Tunstel Space Robotics & Autonomous Control Lead Space Department JHU-APL Planetary Rovers Workshop IEEE ICRA 2010 May 3, 2010 Anchorage, AK Luther Palmer III Assistant Professor, Biomorphic Robotics Lab Department of Computer Science and Engineering University of South Florida

2. EWT-2 Motivation  Continuing campaign of small body exploration  Orbit/rendezvous  landing/touch-and- go sampling  surface exploration (as precursor mission payloads and as astronaut leave-behinds)  Opportunity to drive convergence of technology from different robotics application domains  Focus is on local mobility in persistent contact with the surface in high priority science regions Artist’s concept of NEAR Shoemaker on surface of Eros

3. EWT-3 Technology convergence  Disparate research efforts and missions (e.g., Hayabusa) are maturing enabling technology for asteroid mobility  Hopping vehicles and various rover concepts  Climbing robots for military recon. and search & rescue  Some point(s) of convergence seems possible now or in the near future for gravity-independent locomotion systems  Locomotion without strict dependence on the local gravity vector for traction or stability and local motion control

4. EWT-4 Rolling & Hopping See the paper for this talk for more discussion T. Kubota and T. Yoshimitsu (ISAS/JAXA) Asteroid Exploration Rover, IEEE ICRA 2005, Planetary Rover Workshop

5. EWT-5 Surface characteristics  Weak gravity (micro-g to milli-g) makes it difficult to achieve normal forces usually required for stable surface locomotion  A means to traverse subject to low ground contact pressure or to cling or stick the surface is needed NEAR S/C final Eros landing mosaic

6. EWT-6 Surface characteristics

7. EWT-7 M. Yoshikawa et al (JAXA) COSPAR Capacity Building Workshop on Planetary Science, Montevideo, Uruguay, July 2007

8. EWT-8 Crawling & Climbing See the paper for this talk for more discussion R. Wagner (IEEE ICRA 2007 Planetary Rover Workshop LEMUR IIb (JPL) AWIMR (NGST, JPL, CMU) ASTRO on microgravity emulation testbed (Tohoku University) M. Chacin & K. Yoshida IEEE ICRA 2009 B. Kennedy (CLAWAR 2005

9. EWT-9 Relevant Climbers for Earth-based applications  Gecko-inspired dry adhesives (potential for rapid, low-energy attachment/detachment on various surfaces)  microspine array, or the single spine or claw (latch onto asperities in the surface or dig into soft substrates)  electroadhesion (electrically controllable adhesion between compliant electrodes and various surfaces)  For Earth applications a remaining challenge is producing a single foot and adhesion paradigm that can climb on a variety of both man-made and natural surfaces

10. EWT-10 Relevant Climbers for Earth-based applications DIGbot videos

11. EWT-11 CHALLENGES  Mechanics of controlled ballistic hopping on rotating asteroids and in non-uniform gravity fields  Landing after hopping in such a way as to avoid rebound  Maintaining grip or temporary anchoring while controlling force for closure and compliance  Determining, updating and maintaining knowledge of rover position  Testing and verification of gravity- independent locomotion systems J. Bellerose & D. Sheeres (U. Mischigan, Ann Arbor)

12. EWT-12 Conclusions  Technical challenges can be met with recent technological advances in robotics research  The space of candidate technologies is rich  Earth-based research is advancing useful designs and capabilities (dry adhesive, electroadhesion, and gripping spine)  More attention from the space robotics community is warranted to provide the most capable solutions for science support  Conceivably, solutions for small body mobility would also be applicable for hard-to-access terrain  (e.g., cliff faces, crater walls, and caves) on larger planetary bodies.