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Journal of Sensors
Volume 2017, Article ID 2936041, 9 pages
Research Article

Neck Flexion Angle Estimation during Walking

1Electrical Engineering Department, University of Ulsan, Ulsan, Republic of Korea
2NAMU Inc., Ulsan, Republic of Korea
3Biomedical Engineering Department, University of Ulsan, Ulsan, Republic of Korea

Correspondence should be addressed to Young Soo Suh;

Received 8 June 2017; Accepted 19 October 2017; Published 28 December 2017

Academic Editor: Yeesock Kim

Copyright © 2017 Duc Cong Dang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Neck pain is recently known as the fourth leading cause of disability and the number of patients is apparently increasing. By analyzing the effect of gravitational force on inertial sensor attached to the neck, this study aims to investigate the head flexion posture during walking. The estimated angle is compared with the craniovertebral angle which is measured with an optical tracker. A total of twenty subjects with no history of neck pain or discomfort were examined by walking on the treadmill inside the working range of an optical tracker. In our laboratory settings, the neck flexion angle (NFA) may have a linear relationship with the craniovertebral angle (CVA) in both static case and constant speed walking case. Therefore, inertial sensor, which is lightweight, low cost, and especially free in movement, can be used instead of a camera system. Our proposed estimation method shows its flexibility and gives a result with the mean of absolute error of estimated neck angle varying from 0.48 to 0.58 degrees, which is small enough to use in applications.