🤖 AI Summary
This study addresses the unclear role of frictional anisotropy in the locomotion efficiency of biomimetic snake-like robots across diverse terrains. The authors propose a modular, articulated biomimetic snake skin with rapidly interchangeable scales featuring adjustable angles of attack (15°–45°). A custom friction-testing apparatus and a snake robot platform were developed to simultaneously measure multidirectional friction coefficients—including lateral friction—and forward speed on various surfaces such as grass, tree bark, carpet, and smooth substrates. Experimental results reveal systematic variations in frictional properties with scale angle of attack; however, no consistent correlation was found between friction ratio and locomotion speed. This finding suggests that friction ratio alone is insufficient for predicting robotic performance, offering new insights for the design of biomimetic snake skins.
📝 Abstract
Snake robots are inspired by the ability of biological snakes to move over rock, grass, leaves, soil, up trees, along pavement and more. Their ability to move in multiple distinct environments is due to their legless locomotion strategy, which combines distinct gaits with a skin that exhibits frictional anisotropy. Designing soft robotic snakes with similar capabilities requires an understanding of how this underlying frictional anisotropy should be created in engineered systems, and how variances in the frictional anisotropy ratio affect locomotion speed and direction on different surfaces. While forward and backward frictional ratios have been characterized for previous scale designs, lateral friction and the associated ratios are often overlooked. In this paper, our contributions include: (i) the development of a novel articulated pseudo-skin design that is modular, easy to construct and has removable or replaceable scales; (ii) experimental measurement of the frictional characteristics of otherwise-identical scales at varying angles of attack (15°, 25°, 35°, 45°) on different surfaces of interest (grass, bark, smooth surface, carpet);(iii) separate measurements of locomotion speed for each angle and surface. Consequently, while we observed some consistent trends between frictional coefficients and scale angle, aligning with literature and intuition, we were not able to consistently identify expected correlations between frictional ratios and locomotion speed. We conclude that either frictional ratios alone are not sufficient to predict the observed speed of a snake robot, or that specific measurement approaches are required to accurately capture these ratios.