Robotic modeling of snake traversing large, smooth obstacles reveals stability benefits of body compliance

Abstract

Snakes can move through almost any terrain. Although their locomotion on flat surfaces using planar gaits is inherently stable, when snakes deform their body out of plane to traverse complex terrain, maintaining stability becomes a challenge. On trees and desert dunes, snakes grip branches or brace against depressed sand for stability. However, how they stably surmount obstacles like boulders too large and smooth to gain such anchor points is less understood. Similarly, snake robots are challenged to stably traverse large, smooth obstacles for search and rescue and building inspection. Our recent study discovered that snakes combine body lateral undulation and cantilevering to stably traverse large steps. Here, we developed a snake robot with this gait and snake-like anisotropic friction and used it as a physical model to understand stability principles. The robot traversed steps as high as a third of its body length rapidly and stably. However, on higher steps, it was more likely to fail due to more frequent rolling and flipping over, which was absent in the snake with a compliant body. Adding body compliance reduced the robot roll instability by statistically improving surface contact, without reducing speed. Besides advancing understanding of snake locomotion, our robot achieved high traversal speed surpassing most previous snake robots and approaching snakes, while maintaining high traversal probability.

References in corpus (4)

• Sidewinding with minimal slip: Snake and robot ascent of sandy slopes
• Terradynamically streamlined shapes in animals and robots enhances traversability through densely cluttered terrain
• Body-terrain interaction affects large bump traversal of insects and legged robots
• Snakes partition their body to traverse large steps stably

Cited by in corpus (9)

• Mechanical Intelligence Simplifies Control in Terrestrial Limbless Locomotion
• SenSnake: A snake robot with contact force sensing for studying locomotion in complex 3-D terrain
• Lateral oscillation and body compliance help snakes and snake robots stably traverse large, smooth obstacles
• The need for and feasibility of alternative ground robots to traverse sandy and rocky extraterrestrial terrain
• Locomotor transitions in the potential energy landscape-dominated regime
• Snakes combine vertical and lateral bending to traverse uneven terrain
• A minimalistic stochastic dynamics model of cluttered obstacle traversal
• Contact feedback helps snake robots propel against uneven terrain using vertical bending
• The Effect of Internal Damping on Locomotion in Frictional Environments