Meeting Abstract
Earthworms are characterized by soft, highly flexible and extensible bodies that are capable of locomoting in most terrestrial environments (Trueman1975). Most studies of earthworm movement have focused on the use of retrograde peristaltic gaits. However, worms can also generate axial body bends during locomotion (Gray1968). Such lateral undulation dynamics can aid locomotor function via hooking/anchoring, modify travel orientation, and even generate snake-like undulatory locomotion in environments where peristaltic locomotion results in poor performance. We posit that lateral undulation can play an important role in the creation of soft robotic devices capable of traversing a variety of environments. To understand how the mechanism should move through complex and heterogeneous environments, we built a four-segment pneumatically-driven soft worm-like robot. From our animal experiments, we observed that within confined and heterogeneous environments, the worm uses tip bending to search the environment and to anchor its body. We tested this strategy in our robot both in a confined environment (in an acrylic tube D = 4.3cm) and in a regular lattice (an array of evenly spaced pegs). We started the robot from the same initial position and measured the forward displacement per gait cycle (ΔX). The robot performed better for both cases when it used tip bending (in the tube ΔX =0.11± 0.005 BL/cycle, in the lattice ΔX = 0.06± 0.003 BL/cycle) compared the runs without tip bending (in the tube ΔX =0.05± 0.003 BL/cycle, in the lattice ΔX = 0.012± 0.002BL/cycle). These results show that this simple open-loop, undulatory locomotion strategy can be considered a beneficial method for exploring environments where there is uncertainty about the structure of the terrain.
