24.5 Wednesday, Jan. 4 Rectilinear locomotion of snakes and the design of Scalybot 2 MARVI, H.*; COOK, J. P.; HU, D. L.; Georgia Institute of Technology; Georgia Institute of Technology; Georgia Institute of Technology email@example.com
Snakes use several modes of locomotion including slithering, sidewinding, concertina and rectilinear motion which is the least studied and understood. In rectilinear motion, snakes propel themselves by sending traveling waves of muscular contraction in the posterior direction, in a manner similar to earthworms. This mode of locomotion is especially useful for crawling within crevices, such as found along the trunks of trees. In this combined experimental and theoretical study, we filmed Boa constrictor snakes performing rectilinear locomotion on both horizontal and inclined surfaces. The body kinematics of the snake is parametrized according to the number, frequency, amplitude and phase of the traveling waves observed. We present a mathematical model of a snake as one-dimensional n-linked crawler, in which sliding friction is the dominant propulsive force. Using the measured kinematics and frictional properties of snakeskin, our model predicts 90% of the speed of the snake's center of mass. Our model demonstrates that rectilinear motion is highly sensitive to frictional anisotropy: a snake with isotropic friction and the observed kinematics can barely move, achieving only 4% of the measured speed. Our findings on the mechanisms of rectilinear motion have guided the design and construction of Scalybot 2, a two-link snake-like robot capable of forward and reverse motion as well as steering. Similar to snakes, our robot can enhance the climbing of slopes by motorized adjustment of the angle of attack of its ventral scales, which in turn controls its frictional anisotropy.