Grasping Mechanisms of Anthropomimetic Fingertips

Humanize Robotics

Using robotic fingers that mimic the shape and compliance of the human fingertip (nail, finger pulp, bone, and subcutaneous tissue), we investigate the fingertip functions that enable dexterous grasping. We also apply the findings to prosthetic hands.

Current members: Yuuta FUKASHIRO (M2) · Honori HAGIWARA (M1) · Koh YAOYA (B4)

Anthropomimetic Fingertip

2018 – present

Overview

The human fingertip achieves precise grasping through the combination of fine structures: the distal phalanx, nail, finger pulp, and subcutaneous tissue. We build artificial fingertips that mimic these structures and constructively elucidate the fingertip functions that generate grasping performance.

Technical Features

Faithfully reproduces the shapes of the distal phalanx, nail, finger pulp, and subcutaneous tissue
Two-layer soft structure: soft skin over even softer subcutaneous tissue
Design data for the fingertip and the coin-grasping apparatus released as open source on GitHub

Specifications

Structure: distal phalanx, nail, finger pulp, and subcutaneous tissue
Materials: 3D-printed bones and nail + silicone soft tissue
Design: adaptable to robot hands and prosthetic hands by changing the bone base

Results

Revealed that the asymmetric shape of the distal phalanx improves precision grasping

Revealed that the interaction between the soft finger pulp and the hard nail improves precision grasping

Revealed that skin with mixed stiffness distribution improves coin-grasping performance

Fingertip design data on GitHub

Related Publications

Journal Papers

中村裕哉，呉開元，井上祐希，E. Tonatiuh Jimenez-Borgonio，矢吹佳子，東郷俊太，横井浩史，"同一形状部材による劣駆動指屈曲メカニズムを有する義手用ロボットハンドの開発"，日本ロボット学会誌，早期公開，2026.1.23. (in Japanese)
JIANG HAI，中村裕哉，井上祐希，呉開元，山野井佑介，矢吹佳子，東郷俊太，横井浩史，"把持性能向上のための受動安定性を有する筋電義手用指機構の開発"，日本ロボット学会誌，Vol. 44，No. 4，pp. 421–424，2026．doi: 10.7210/jrsj.44.421. (in Japanese)
Ayane Kumagai, Yoshinobu Obata, Yoshiko Yabuki, Yinlai Jiang, Hiroshi Yokoi, Shunta Togo, "Improvement of precision grasping performance by interaction between soft finger pulp and hard nail," Soft Robotics, Vol. 10, No. 2, pp. 345-353, 2023. doi: 10.1089/soro.2021.0231
Ayane Kumagai, Yoshinobu Obata, Yoshiko Yabuki, Yinlai Jiang, Hiroshi Yokoi, Shunta Togo, "Asymmetric shape of distal phalanx of human finger improves precision grasping," Scientific Reports, Vol. 11, No. 10402, pp. 1–10, 2021. doi: 10.1038/s41598-021-89791-3
Yoshinobu Obata, Ayane Kumagai, Yoshiko Yabuki, Shunta Togo, Yinlai Jiang, Hiroshi Yokoi, "Development of a two-layered elastic glove for dynamic stable grasping of powered prosthetic hand," Journal of the Robotics Society of Japan, Vol. 39，No. 8，pp. 744–750，2021．doi: 10.7210/jrsj.39.744

International Conference Papers

Ayane Kumagai, Yoshinobu Obata, Yoshiko Yabuki, Yinlai Jiang, Yokoi Hiroshi and Shunta Togo, “Comparison of precision grasping performance between artificial fingers with and without nails,” 2022 IEEE 4th Global Conference on Life Science and Technologies (LifeTech2022), pp. 380–381, Osaka, Japan, 7-9 Mar. 2022.
Ayane Kumagai, Yoshinobu Obata, Yinlai Jiang, Hiroshi Yokoi and Shunta Togo, “Evaluation of the grasping ability by artificial finger based on the morphology of distal phalanx,” 2020 IEEE 2nd Global Conference on Life Science and Technologies (LifeTech 2020), pp. 334-335, Kyoto Japan, 10–12 Mar. 2020.
Yoshinobu Obata, Ayane Kumagai, Shunta Togo, Yinlai Jiang and Hiroshi Yokoi, “Analysis of two-layer artificial soft fingertip for dynamic stable grasping,” 2020 IEEE 2nd Global Conference on Life Science and Technologies (LifeTech 2020), pp. 362-363, Kyoto Japan, 10–12 Mar. 2020.

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