1. Empirical Mode Decomposition-Derived Entropy Features Are Beneficial to Distinguish Elderly People with a Falling History on a Force Plate Signal
- Author
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Li-Wei Chou, Kang-Ming Chang, Yi-Chun Wei, and Mei-Kuei Lu
- Subjects
Science ,QC1-999 ,fall risk ,approximate entropy ,General Physics and Astronomy ,02 engineering and technology ,sample entropy ,Astrophysics ,Signal ,Approximate entropy ,Hilbert–Huang transform ,Article ,03 medical and health sciences ,0302 clinical medicine ,Statistics ,0202 electrical engineering, electronic engineering, information engineering ,intrinsic mode functions ,Time domain ,Entropy (energy dispersal) ,empirical mode decomposition ,Mathematics ,Physics ,QB460-466 ,Sample entropy ,020201 artificial intelligence & image processing ,Falling (sensation) ,030217 neurology & neurosurgery ,Center of pressure (fluid mechanics) - Abstract
Fall risk prediction is an important issue for the elderly. A center of pressure signal, derived from a force plate, is useful for the estimation of body calibration. However, it is still difficult to distinguish elderly people’s fall history by using a force plate signal. In this study, older adults with and without a history of falls were recruited to stand still for 60 s on a force plate. Forces in the x, y and z directions (Fx, Fy, and Fz) and center of pressure in the anteroposterior (COPx) and mediolateral directions (COPy) were derived. There were 49 subjects in the non-fall group, with an average age of 71.67 (standard derivation: 6.56). There were also 27 subjects in the fall group, with an average age of 70.66 (standard derivation: 6.38). Five signal series—forces in x, y, z (Fx, Fy, Fz), COPX, and COPy directions—were used. These five signals were further decomposed with empirical mode decomposition (EMD) with seven intrinsic mode functions. Time domain features (mean, standard derivation and coefficient of variations) and entropy features (approximate entropy and sample entropy) of the original signals and EMD-derived signals were extracted. Results showed that features extracted from the raw COP data did not differ significantly between the fall and non-fall groups. There were 10 features extracted using EMD, with significant differences observed among fall and non-fall groups. These included four features from COPx and two features from COPy, Fx and Fz.
- Published
- 2021