Quasi-static motion of a new serial snake-like robot on a water surface: a geometrical approach

This paper reports methods to compute the equilibrium stances of a new snake-like robot designed to stabilize its head on a free water surface. To adjust rapidly the stability of the robot, this bio-inspired robot can rotate independently each body-shell, and modify the level of immersion of each module. To predict the stable stance accessible by this additional degree of freedom, a model is developed to compute the equilibrium configurations of the robot from a given parametrization of the body shape. Then, an algorithm is introduced to compute a sequence of controlled body deformations, such that the head configuration relatively to the water surface remains unchanged. Finally, we explore in simulation stances and quasi-static gaits, and investigate to what extent the buoyancy and the body deformations can be used to stabilize the head of the snake-like robot.