Robotic Snake Locomotion Exploiting Body Compliance and Uniform Body Tensions

The undulatory locomotion of snakes is one unique wonder of mechanical motions in nature. Traditionally, snakes were thought to push surrounding objects to propel their motion. However, this does not explain their forward locomotion and sidewinding on a flat surface. Recent studies have shown that the snake's forward locomotion and sidewinding are aided by a nonuniform ground-contact distribution. In this article, we propose a novel control strategy to achieve nonuniform ground contacts for a robotic snake locomotion using body compliance and uniform body tension. First, we present a set of mechanical analyses for a continuum snake model. Then, we demonstrate that the deflection under gravity resulting from body compliance and uniform body tension naturally yields the contact distributions required for forward and backward locomotion and sidewinding. Finally, a simple control strategy is suggested for a robotic snake locomotion, which was validated through dynamic simulations and physical experiments.