Supplementary material from "Effect of data length on time delay and embedding dimension for calculating the Lyapunov exponent in walking"
Posted on 2020-06-27 - 03:17
The Lyapunov exponent (LyE) is a trending measure for characterizing gait stability. Previous studies have shown that data length has an effect on the resultant LyE, but the origin of why it changes is unknown. This study investigates if data length affects the choice of time delay and embedding dimension when reconstructing the phase space, which is a requirement for calculating the LyE. The effect of three different preprocessing methods on reconstructing the gait attractor was also investigated. Lumbar accelerometer data were collected from 10 healthy subjects walking on a treadmill at their preferred walking speed for 30 min. Our results show that time delay was not sensitive to the amount of data used during calculation. However, the embedding dimension had a minimum data requirement of 200 or 300 gait cycles, depending on the preprocessing method used, to determine the steady-state value of the embedding dimension. This study also found that preprocessing the data using a fixed number of strides or a fixed number of data points had significantly different values for time delay compared to a time series that used a fixed number of normalized gait cycles, which have a fixed number of data points per stride. Thus, comparing LyE values should match the method of calculation using either a fixed number of strides or a fixed number of data points.
CITE THIS COLLECTION
3D Printing in Medicine
3D-Printed Materials and Systems
Abhandlungen aus dem Mathematischen Seminar der Universität Hamburg
ABI Technik (German)
Academy of Management Discoveries
Academy of Management Journal
Academy of Management Learning and Education
Academy of Management Perspectives
Academy of Management Proceedings
Academy of Management Review
Hussain, Victoria Smith; Spano, Mark L.; Lockhart, Thurmon E. (2020). Supplementary material from "Effect of data length on time delay and embedding dimension for calculating the Lyapunov exponent in walking". The Royal Society. Collection. https://doi.org/10.6084/m9.figshare.c.5042045.v1
Select your citation style and then place your mouse over the citation text to select it.
Read the peer-reviewed publication
Victoria Smith Hussain
Mark L. Spano
Thurmon E. Lockhart