EPL, 87 (2009) 58003
DOI: 10.1209/0295-5075/87/58003

Least-action principle in gait

Y. F. Fan¹, M. Loan², Y. B. Fan³, Z. Y. Li⁴ and D. L. Luo<sup>1

1</sup>   Center for Scientific Research, Guangzhou Institute of Physical Education - Guangzhou 510500, China
²   International School, Jinan University - Guangzhou 510632, China
³   Bioengineering Department, Beijing University of Aeronautics and Astronautics - Beijing 100191, China
⁴   College of Foreign Languages, Jinan University - Guangzhou 510632, China

tfyf@mailer.gipe.edu.cn

received 8 July 2009; accepted in final form 24 August 2009; published September 2009
published online 22 September 2009

Abstract
We apply the laws of human gait vertical ground reaction force and discover the existence of the phenomenon of least-action principle in gait. Using a capacitive mat transducer system, we obtain the variations of human gait vertical ground reaction force and establish a structure equation for the resultant of such a force. Defining the deviation of vertical force as an action function, we observe from our gait optimization analysis the least-action principle at half of the stride time. We develop an evaluation index of mechanical-energy consumption based upon the least-action principle in gait. We conclude that these observations can be employed to enhance the accountability of gait evaluation.

PACS
87.85.G - Biomechanics.
87.85.gj - Movement and locomotion.
87.55.de - Optimization.

© EPLA 2009