Triaxial ground reaction forces of earthworm rectilinear locomotion: measurement, analysis, and implications for robot modeling

• Published in: Acta mechanica Sinica Vol. 40; no. 2
• Main Authors: Fang, Hongbin, Shi, Rui, Xu, Jian
• Format: Journal Article
• Language: English
• Published: Beijing The Chinese Society of Theoretical and Applied Mechanics; Institute of Mechanics, Chinese Academy of Sciences 01.02.2024; Springer Nature B.V
• Edition: English ed.
• Subjects: Biomechanics; Classical and Continuum Physics; Computational Intelligence; Confined spaces; Engineering; Engineering Fluid Dynamics; Force plates; Locomotion; Research Paper; Robot dynamics; Robots; Strain gauges; Theoretical and Applied Mechanics; Worms; Earthworm biomechanics; Triaxial force measurement; Resistance coefficient; Earthworm-like robot; Miniature force plate
• ISSN: 0567-7718; 1614-3116
• DOI: 10.1007/s10409-023-23198-x

Although earthworms are recognized for their excellent mobility in confined environments, little is known about the triaxial ground reaction forces (GRFs) they produce during locomotion. This study explores the triaxial GRF characteristics of the earthworm during rectilinear locomotion and their implications for robot development. A strain gauge-based triaxial miniature force plate is designed to measure the triaxial GRFs of Pheretima guillelmi during rectilinear locomotion. By correlating the time histories of the measured GRFs with recorded videos, the motion of one cycle of the earthworm is divided into three phases, and the relationship between the deformation of the earthworm’s body and the characteristics of the GRFs is established. Based on the experimental data of nine subjects, this study also statistically analyzes the characteristics of the GRFs and derives a model of the earthworm’s resistance coefficient during its rectilinear motion. Furthermore, this study presents models of resistance coefficients closely related to robot segment/section deformations for both discrete and continuous configurations of earthworm-like robots. The results of this study are instructive for understanding earthworm locomotion biomechanics and designing and regulating the interface between the earthworm-like robot and the ground.