Side-Impact Collision: Mechanics of Obstacle Negotiation in Sidewinding Snakes [article]

Henry C. Astley, Jennifer M. Rieser, Abdul Kaba, Veronica M. Paez, Ian Tomkinson, Joseph R Mendelson, Daniel I. Goldman
2020 bioRxiv   pre-print
Snakes excel at moving through cluttered environments, and heterogeneities can be used as propulsive contacts for snakes performing lateral undulation. However, sidewinding, often associated with sandy deserts, cuts a broad path through the environment that may increase the vulnerability to obstacles. Our prior work demonstrated that sidewinding can be represented as a pair of orthogonal body waves (vertical and horizontal) that can be independently modulated to achieve high maneuverability and
more » ... maneuverability and incline ascent, suggesting that sidewinders may also use template modulations to negotiate obstacles. To test this hypothesis, we recorded overhead video of four sidewinder rattlesnakes (Crotalus cerastes) crossing a line of vertical pegs placed in the substrate. Snakes used three methods to traverse the obstacles: a Propagate Through behavior in which the lifted moving portion of the snake was deformed around the peg and dragged through as the snake continued sidewinding (115/160 runs), Reversal turns that reorient the snake entirely (35/160), or switching to Concertina locomotion (10/160). The Propagate- Through response was only used if the anterior-most region of static contact would propagate along a path anterior to the peg, or if a new region of static contact could be formed near the head to satisfy this condition; otherwise, snakes could only use Reversal Turns or switch to Concertina locomotion. Reversal Turns allowed the snake to re-orient and either escape without further peg contact or resorting to Propagate Through. We developed an algorithm to reproduce the Propagate Through behavior in a robotic model using a modulation of the two-wave template. This range of behavioral strategies provides sidewinders with a versatile range of options for effectively negotiating obstacles in their natural habitat, as well as provide insights into the design and control of robotic systems dealing with heterogeneous habitats.
doi:10.1101/2020.04.22.055681 fatcat:hrbomjuosfgynfneglc64tm56m