Sensors 2012, 12(11), 15338-15355; doi:10.3390/s121115338
Article

Exploration and Implementation of a Pre-Impact Fall Recognition Method Based on an Inertial Body Sensor Network

email, email, email, email, email, email and * email
Received: 20 August 2012; in revised form: 16 October 2012 / Accepted: 17 October 2012 / Published: 8 November 2012
(This article belongs to the Special Issue Body Sensor Networks for Healthcare and Pervasive Applications)
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.
Abstract: The unintentional injuries due to falls in elderly people give rise to a multitude of health and economic problems due to the growing aging population. The use of early pre-impact fall alarm and self-protective control could greatly reduce fall injuries. This paper aimed to explore and implement a pre-impact fall recognition/alarm method for free-direction fall activities based on understanding of the pre-impact lead time of falls and the angle of body postural stability using an inertial body sensor network. Eight healthy Asian adult subjects were arranged to perform three kinds of daily living activities and three kinds of fall activities. Nine MTx sensor modules were used to measure the body segmental kinematic characteristics of each subject for pre-impact fall recognition/alarm. Our analysis of the kinematic features of human body segments showed that the chest was the optimal sensor placement for an early pre-impact recognition/alarm (i.e., prediction/alarm of a fall event before it happens) and post-fall detection (i.e., detection of a fall event after it already happened). Furthermore, by comparative analysis of threshold levels for acceleration and angular rate, two acceleration thresholds were determined for early pre-impact alarm (7 m/s/s) and post-fall detection (20 m/s/s) under experimental conditions. The critical angles of postural stability of torso segment in three kinds of fall activities (forward, sideway and backward fall) were determined as 23.9 ± 3.3, 49.9 ± 4.1 and 9.9 ± 2.5 degrees, respectively, and the relative average pre-impact lead times were 329 ± 21, 265 ± 35 and 257 ± 36 ms. The results implied that among the three fall activities the sideway fall was associated with the largest postural stability angle and the forward fall was associated with the longest time to adjust body angle to avoid the fall; the backward fall was the most difficult to avoid among the three kinds of fall events due to the toughest combination of shortest lead time and smallest angle of postural stability which made it difficult for the self-protective control mechanism to adjust the body in time to avoid falling down.
Keywords: biomechanics of fall; early pre-impact fall alarm; pre-impact lead time; postural instability; body sensor network
PDF Full-text Download PDF Full-Text [1124 KB, uploaded 21 June 2014 05:11 CEST]

Export to BibTeX |
EndNote


MDPI and ACS Style

Zhao, G.; Mei, Z.; Liang, D.; Ivanov, K.; Guo, Y.; Wang, Y.; Wang, L. Exploration and Implementation of a Pre-Impact Fall Recognition Method Based on an Inertial Body Sensor Network. Sensors 2012, 12, 15338-15355.

AMA Style

Zhao G, Mei Z, Liang D, Ivanov K, Guo Y, Wang Y, Wang L. Exploration and Implementation of a Pre-Impact Fall Recognition Method Based on an Inertial Body Sensor Network. Sensors. 2012; 12(11):15338-15355.

Chicago/Turabian Style

Zhao, Guoru; Mei, Zhanyong; Liang, Ding; Ivanov, Kamen; Guo, Yanwei; Wang, Yongfeng; Wang, Lei. 2012. "Exploration and Implementation of a Pre-Impact Fall Recognition Method Based on an Inertial Body Sensor Network." Sensors 12, no. 11: 15338-15355.


Sensors EISSN 1424-8220 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert