A Multigait Continuous Flexible Snake Robot for Locomotion in Complex Terrain

This article presents a novel multigait continuous flexible snake mobile robot based on rotating, twisting, and untwisting of a flexible spring. The proposed robot combines the advantages of a twisted flexible helical spring and a string of rigid planar articulated circular shells into a unique wheel-less structure with 100 degrees of freedom per meter length. By adjusting the rotation direction and speed of two motors set on both ends of the constrained spring, the robot performs different motions. A kinematics model indicates multiple motions, i.e., wave-like, straightening, and curling motions can be realized through rotating, twisting, and untwisting of the helical spring, respectively. Through different motions, the robot achieves sidewinding gait, concertina gait, and side-pushing locomotion gait in open space, while lateral and vertical undulations in confined space. Locomotion experiments on floor, on sands, under water, in tubes, and other complex terrain are conducted, which indicates its potential for rescue and exploration missions in complex environments.