Investigation on the Cooperative Grasping Capabilities of Human Thumb and Index Finger

Xiaojing Chen; Zhiguo Li; Yuqing Wang; Jizhan Liu; Dezong Zhao

doi:10.3389/fnbot.2019.00092

Investigation on the Cooperative Grasping Capabilities of Human Thumb and Index Finger

Front Neurorobot. 2019 Nov 5:13:92. doi: 10.3389/fnbot.2019.00092. eCollection 2019.

Authors

Xiaojing Chen^{1

2}, Zhiguo Li¹, Yuqing Wang², Jizhan Liu³, Dezong Zhao⁴

Affiliations

¹ College of Mechanical and Electronic Engineering, Northwest A&F University, Yangling, China.
² School of Mechanical and Power Engineering, Henan Polytechnic University, Jiaozuo, China.
³ School of Agricultural Equipment Engineering, Jiangsu University, Zhenjiang, China.
⁴ Department of Aeronautical and Automotive Engineering, Loughborough University, Loughborough, United Kingdom.

Abstract

The maximum cooperative grasping mass and diameter of the human thumb and index finger were investigated by 7560 grasp-release trials on various masses of solid cylinders and various sizes of rings. The maximum grasping mass of the participants' thumb-index finger depended on gender, age and the sum of thumb-index finger lengths (P < 0.05), but not on the hand-used and ratio of index finger to thumb length (P > 0.05). The maximum grasping diameter of the participants' thumb-index finger depended on the age, sum of thumb-index finger lengths and ratio of index finger to thumb length (P < 0.05), but not on the gender and hand-used (P > 0.05). There was a non-linear regression model for the dependence of the maximum grasping mass on gender, age and the sum of thumb-index finger lengths and another non-linear regression model for the dependence of the maximum grasping diameter on the age, sum of thumb-index finger lengths and ratio of index finger to thumb length. Two regression models were useful in the optimal size design of robotic hands intending to replicate thumb-index finger grasping ability. This research can help to define not only a reasonable grasp mass and size for a bionic robotic hand, but also the requirements for hand rehabilitation.

Keywords: cooperative grasping capabilities; human characteristics; object mass and diameter; robotic hand; thumb and index finger.