A threshold-based fall-detection algorithm using a bi-axial gyroscope sensor

Bourke, A.K.; Lyons, G.M.

doi:10.1016/j.medengphy.2006.12.001

« Previous Next »Medical Engineering & Physics
Volume 30, Issue 1 , Pages 84-90, January 2008

A threshold-based fall-detection algorithm using a bi-axial gyroscope sensor

Biomedical Electronics Laboratory, Department of Electronic and Computer Engineering, University of Limerick, Limerick, Ireland

Received 5 September 2006; received in revised form 28 November 2006; accepted 3 December 2006. published online 12 January 2007.

Abstract

A threshold-based algorithm, to distinguish between Activities of Daily Living (ADL) and falls is described. A gyroscope based fall-detection sensor array is used. Using simulated-falls performed by young volunteers under supervised conditions onto crash mats and ADL performed by elderly subjects, the ability to discriminate between falls and ADL was achieved using a bi-axial gyroscope sensor mounted on the trunk, measuring pitch and roll angular velocities, and a threshold-based algorithm. Data analysis was performed using Matlab^® to determine the angular accelerations, angular velocities and changes in trunk angle recorded, during eight different fall and ADL types. Three thresholds were identified so that a fall could be distinguished from an ADL: if the resultant angular velocity is greater than 3.1rads/s (Fall Threshold 1), the resultant angular acceleration is greater than 0.05rads/s² (Fall Threshold 2), and the resultant change in trunk-angle is greater than 0.59rad (Fall Threshold 3), a fall is detected. Results show that falls can be distinguished from ADL with 100% accuracy, for a total data set of 480 movements.