Meeting Abstract
Many snakes traverse complex 3-D terrain such as mountains and forests with obstacles comparable to their body size. Similarly, snake robots have the potential to traverse terrain with large obstacles like earthquake rubble and construction sites for search and rescue and structural examination. However, with the exception of branch climbing, burrowing, and gliding, laboratory studies of snake locomotion focused on that on simple flat surfaces. Here, to understand snake locomotion in complex 3-D terrain and provide inspiration for snake robots, we study how the generalist variable kingsnake traversed a large step as high as 40% body length. The snake partitioned its body into three sections that deformed in separate planes with distinct functions. The body sections below and above the step oscillated laterally on the horizontal surface to stabilize and propel the animal forward. The body section in between straightened and cantilevered in a vertical plane to bridge the large height increase. All three sections travelled down the body fluidly as the animal progressed, allowing the snake to always conform to the terrain. In addition, despite changes in step height and surface friction, this movement pattern persisted. To test this gait as a control template for robots, we developed a snake robot capable of horizontal and vertical body deformation with anisotropic friction as found in snakes. Using a partitioned gait, the robot traversed a step as high as 30% body length with 100% probability and at speeds surpassing previous snake robots that used artificial, follow-the-leader gaits. However, as step height further increased to 40% body length, the robot failed more often due to diminishing stability and traction from poorer body-terrain contact (another talk by Fu Q et al. discusses how body compliance helps alleviate this problem).
