Single-Motor-Driven Robotic Hand With Multiple Grippers Using Gravity-Driven Torque-Path Switching Mechanism
Toshihiro Nishimura, Hono Okatsu, Tetsuyou Watanabe
Abstract
This letter presents a novel multi-gripper robotic hand system driven by a single motor. To achieve the operation of multiple grippers through a single motor, this study develops a new transmission mechanism that switches the torque path to each gripper using magnetic coupling and gravity. The motor torque is transmitted to a target gripper via the magnetic couplings, and switching the target gripper is triggered by magnetic decoupling induced by intentional overtorque. Once decoupled, the pendulum-suspended motor swings under gravity to align with the next target gripper, achieving autonomous switching without additional actuators. In this letter, theoretical analysis of the magnetic couplings and design considerations to achieve the desired behavior are presented. Two prototypes—a dual-gripper hand and a five-gripper hand—were developed to validate the proposed concept. Quantitative evaluations demonstrate that the proposed system achieves a switching duration of 0.41 s with high repeatability, as well as robust and durable operation. Grasping experiments demonstrate versatile object handling and sequential multi-object manipulation using selective gripper switching.
BibTeX
@inproceedings{ral2026_singlemotordrive,
title = {Single-Motor-Driven Robotic Hand With Multiple Grippers Using Gravity-Driven Torque-Path Switching Mechanism},
author = {Toshihiro Nishimura and Hono Okatsu and Tetsuyou Watanabe},
booktitle = {RA-L 2026},
year = {2026}
}