Development of an under-actuated tendon-driven planar elephant robot based on synergistic motion analysis
Koki Kitabayashi, Takumi Aotani, Ryuta Ozawa
Abstract
Elephants cannot intentionally control individual trunk muscles but instead generate coordinated movements. This coordination, known as kinematic synergy, allows muscles to work together, reducing the controlled degrees of freedom (DOF) while enhancing motion efficiency. In this paper, we develop an elephant trunk robot that generates coordinated motions with only a few actuators inspired by kinematic synergy. First, we analyze elephant trunk motion using video data and extract the principal components that closely approximate actual movements. Next, we design a robot based on an underactuated tendon-driven transmission to reproduce the selected principal components and a control system to reduce tracking errors. Especially, we focus on designing tendons to confine the motion within the space spanned by the principal components. Finally, we implement the control system and evaluate the robot’s performance in replicating trunk motion with a limited number of actuators. By generating coordinated motion, we showed the effectiveness of the transmission system design method and the improvement in the motion accuracy by the control system.
BibTeX
@inproceedings{iros2025_developmentofanu,
title = {Development of an under-actuated tendon-driven planar elephant robot based on synergistic motion analysis},
author = {Koki Kitabayashi and Takumi Aotani and Ryuta Ozawa},
booktitle = {IROS 2025},
year = {2025}
}