Influence of Setae of Earthworm-like Robot on Peristaltic Propulsion

We numerically investigated the peristaltic motions of an earthworm-like robot model with and without setae. The model was constituted of a Mass-Spring-Damper (MSD) unit which has taken the unsteady effects of a fluid into account. Though the model could move even if it did not have setae, direction and speed of its movement depended on the initial motion of the vibration. The earthworm-like seta was found to contribute to the determination of not only direction of motion, but also speed of the model. We tested different contact angles of the seta, different values of friction between seta and wall, and effects of density and viscosity of fluid around the body. The body moved most quickly when the contact angle of seta was 45 degrees. The speed of the earthworm-like robot was found to depend on the density of fluid and the friction acting on the seta during peristaltic motion.