Soft Snake Robots: Investigating the Effects of Gait Parameters on Locomotion in Complex Terrains

Abstract

Compliant materials used to create soft robots can better replicate biological structures than typical rigid materials. We can look to nature for developing locomotion strategies for these soft-bodied robots. In this work, snakes were used as inspiration to create an inextensible, soft robot which was used as a platform to test gaits in terrain composed of granular media ranging from fine sand to stone. Snakes vary the speed and amplitude of the traveling wave used in lateral undulation to navigate different environments. We used these gait parameters to develop and test a set of custom gaits that varied the phase offset of the sequence of waves as well as using the best performing gait to test how the amplitude of the wave effects locomotion over the selected terrains. These tests provide preliminary evidence that altering these parameters effects the robot's ability to traverse different terrains. The developed robot is also tested in environments specific to applications for snake robots to show how a soft snake robot can be potentially more effective in these environment. The highest performing gait-curvature combination was the half-activation gait (where the back actuator was activated half as long as the front)with a 135° swept angle. It reached a velocity of 2.2 mm/s or 0.011 body-lengths/s on paper, which was the best performing terrain.