Area Design of Keyboard Layout for Comfortable Texting Ability with the Thumb Jacobian Matrix

ABSTRACT

The objective of this paper is to develop a theory for designing the keyboard area of smartphones, and endowing the users with comfortable texting ability via one thumb. In light of the fact that most users tend to hold the smartphone in one hand and manipulate with one thumb in daily life, this paper extracts the thumb kinematic chain from the thumb anatomy of the human hand, and defines the manipulation comfort ellipsoid of the thumb. Then some indexes such as the morphology and volume of the comfort ellipsoid, and the condition number of the thumb Jacobian are presented to evaluate the manipulation comfort of the thumb. Finally, the design problem of the smartphone’s keyboard area is transformed into an optimization problem that determines the most comfortable manipulation space for the human thumb. The proposed quantitative study method of the thumb manipulation comfort is verified by 12 subjects who hold a smartphone with one hand and manipulate the screen with one thumb, and the most comfortable keyboard layout of smartphone is determined for the 12 subjects. The proposed method for the manipulation comfort of the human thumb bridges the gap between the layout planning of soft keyboard of smartphones and the comfort of single thumb manipulation.

Acknowledgments

We would like to thank the support of National High-tech Research and Development Program of China under Grant 2018YFB1305400, and National Natural Science Foundation of China under Grant U1913205 and 61533004. Thanks also give to Mr. Baiyang Sun for his help in data acquisition and preprocessing.

Additional information

Funding

This work was supported by the National High-tech Research and Development Program of China [2018YFB1305400]; National Natural Science Foundation of China [61533004]; National Natural Science Foundation of China [U1913205]; National Natural Science Foundation of China under Grant U1913205600, 61533004 and 71931005.

Notes on contributors

Le Xiong

Le Xiong received the BBA degree from University of Iowa, Iowa City, IA, in 2014, and M.S. degree in Operations Analytics and Management from Worcester Polytechnic Institute, Worcester, MA, in 2017. Now she is working toward the Ph.D. degree in management science with Huazhong University of Science and Technology.

Chenglong Fu

Chenglong Fu is currently a professor with Southern University of Science and Technology and the director of Shenzhen Key Laboratory of Biomimetic Robotics and Intelligent Systems. His research interests include robotics and human-machine interaction. He has presided over more than 30 research projects and published more than 100 academic papers.

Shiming Deng

Shiming Deng received his B.E. degree from Peking University, China, in 1995, M.S. and Ph.D. degrees from University of California, Berkeley, in 1999 and 2003 respectively. Now he is a Professor with Huazhong University of Science and Technology, Wuhan, China. His research interests include industrial engineering, ergonomics, and operations research.