Department of Physics, Georgia Institute of Technology, Atlanta, United States
Henry C Astley
Department of Physics, Georgia Institute of Technology, Atlanta, United States; Biology and the Department of Polymer Science, University of Akron, Akron, United States
Jennifer M Rieser
Department of Physics, Georgia Institute of Technology, Atlanta, United States
Shashank Agarwal
Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, United States
Christian Hubicki
Department of Physics, Georgia Institute of Technology, Atlanta, United States; Department of Mechanical Engineering, Florida A&M University-Florida State University, Tallahassee, United States
Alex M Hubbard
Department of Physics, Georgia Institute of Technology, Atlanta, United States
Kelimar Diaz
Department of Physics, Georgia Institute of Technology, Atlanta, United States
Joseph R Mendelson III
School of Biological Sciences, Georgia Institute of Technology, Atlanta, United States; Zoo Atlanta, Atlanta, United States
Ken Kamrin
Department of Mechanical Engineering, Florida A&M University-Florida State University, Tallahassee, United States
While terrestrial locomotors often contend with permanently deformable substrates like sand, soil, and mud, principles of motion on such materials are lacking. We study the desert-specialist shovel-nosed snake traversing a model sand and find body inertia is negligible despite rapid transit and speed dependent granular reaction forces. New surface resistive force theory (RFT) calculation reveals how wave shape in these snakes minimizes material memory effects and optimizes escape performance given physiological power limitations. RFT explains the morphology and waveform-dependent performance of a diversity of non-sand-specialist snakes but overestimates the capability of those snakes which suffer high lateral slipping of the body. Robophysical experiments recapitulate aspects of these failure-prone snakes and elucidate how re-encountering previously deformed material hinders performance. This study reveals how memory effects stymied the locomotion of a diversity of snakes in our previous studies (Marvi et al., 2014) and indicates avenues to improve all-terrain robots.
