A study examines the role of passive dynamics in the movement of a desert snake, lending potential insights into the design of limbless robots. Limbless vertebrates such as snakes slither across sandy surfaces by pressing the curves of their sinuous trunks against transient piles of sand to propel themselves forward. However, whether snakes use passive mechanics or fine motor control based on sensory input from the environment to navigate obstacle-strewn terrain remains unclear. Perrin Schiebel and colleagues used high-speed video cameras to monitor the movement of the shovel-nosed desert snake (Chionactis occipitalis) across an experimental track affixed with six force-sensitive posts; C. occipitalis normally uses a body-deforming sinusoidal wave to propel itself along sandy desert terrain. Analysis of 253 trajectories of eight snakes revealed that the snakes did not alter their self-deformation pattern or the waveform to avoid or grab the posts. Instead, the snakes maintained their motor program, relying on passive dynamics, which evoked the diffraction pattern of subatomic particles, to navigate without additional neural input. Modeling analysis revealed that muscle activation allowed the snakes to buckle around the posts. According to the authors, the findings suggest that incorporating principles of passive dynamics into the design of snake-like robots might improve their mobility in complex terrains.
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Article #18-08675: "Mechanical diffraction reveals the role of passive dynamics in a slithering snake," by Perrin Schiebel et al.
MEDIA CONTACT: John Toon, Georgia Institute of Technology, Atlanta, GA; tel: 404-894-6986; email: <john.toon@comm.gatech.edu>
Journal
Proceedings of the National Academy of Sciences