Tip Extending Torus Mechanism based on Nemertea Proboscis

-Proposal of hydrostatic skeleton structure capable of retraction while bending-

Abstract

Soft robots have attracted much attention in recent years owing to their high adaptability. Long articulated soft robots enable diverse operations, and tip-extending robots that navigate their environment through growth are highly effective in robotic search applications. Since the robot membrane extends from the tip, these robots can lengthen without any friction from the environment. However, the flexibility of the membrane inhibits tip retraction and causes buckling. To resolve this issue, two methods have been proposed; increase the pressure of the internal fluid to enhance the rigidity and mount an actuator at the tip. The disadvantage of the former is that the pressure is limited by the membrane strength, while the second method leads to the robot complexity. In this paper, we present a tip-retraction mechanism without buckling that takes advantage of the friction from the external environment.