To read the full version of this content please select one of the options below:

Improving stability in physical human–robot interaction by estimating human hand stiffness and a vibration index

Feifei Bian (Harbin Institute of Technology, Harbin, China)
Danmei Ren (Fujian (Quanzhou) HIT Institute of Engineering and Technology, Quanzhou, China)
Ruifeng Li (Harbin Institute of Technology, Harbin, China)
Peidong Liang (Fujian (Quanzhou) HIT Institute of Engineering and Technology, Quanzhou, China)

Industrial Robot

ISSN: 0143-991x

Article publication date: 30 October 2018

Issue publication date: 5 August 2019

Abstract

Purpose

The purpose of this paper is to eliminate instability which may occur when a human stiffens his arms in physical human–robot interaction by estimating the human hand stiffness and presenting a modified vibration index.

Design/methodology/approach

Human hand stiffness is first estimated in real time as a prior indicator of instability by capturing the arm configuration and modeling the level of muscle co-contraction in the human’s arms. A time-domain vibration index based on the interaction force is then modified to reduce the delay in instability detection. The instability is confirmed when the vibration index exceeds a given threshold. The virtual damping coefficient in admittance controller is adjusted accordingly to ensure stability in physical human–robot interaction.

Findings

By estimating the human hand stiffness and modifying the vibration index, the instability which may occur in stiff environment in physical human–robot interaction is detected and eliminated, and the time delay is reduced. The experimental results demonstrate significant improvement in stabilizing the system when the human operator stiffens his arms.

Originality/value

The originality is in estimating the human hand stiffness online as a prior indicator of instability by capturing the arm configuration and modeling the level of muscle co-contraction in the human’s arms. A modification of the vibration index is also an originality to reduce the time delay of instability detection.

Keywords

Acknowledgements

Funding: This work was partially supported by National Key R&D Program of China (2017YFB1301600), the National Natural Science Foundation of China (61673136), and the High Level Talent Project of Quanzhou City under Grant No.2017ZT015.

Citation

Bian, F., Ren, D., Li, R. and Liang, P. (2019), "Improving stability in physical human–robot interaction by estimating human hand stiffness and a vibration index", Industrial Robot, Vol. 46 No. 4, pp. 529-540. https://doi.org/10.1108/IR-05-2018-0111

Publisher

:

Emerald Publishing Limited

Copyright © 2018, Emerald Publishing Limited