An electricity-free snake-like propulsion mechanism driven and controlled by fluids

Unlike ordinary snake-like robots, a propulsion mechanism that does not rely on electricity for control and actuation is proposed in this paper. Analysis of a snake´s propulsion based on a continuum model unveils that the lateral undulation can be achieved by bending the body at torque proportional to the curvature derivative of the body curve, as observed in muscular activities of biological snakes. Thanks to the simplicity of this principle, a pure mechanical structure comprising a fluid servomechanism can be realized. The proposed propulsion mechanism also consists of gears that propagate the joint angle information to the posterior joint to mechanically simulate curvature derivative.