Abstract
Miniature, wearable sensor modules are a promising technology to monitor activities of daily living (ADL) over extended periods of time. To assure both user compliance and meaningful results, the selection and placement site of sensors requires careful consideration. We investigated these aspects for the classification of 16 ADL in 6 healthy subjects under laboratory conditions using ReSense, our custom-made inertial measurement unit enhanced with a barometric pressure sensor used to capture activity-related altitude changes. Subjects wore a module on each wrist and ankle, and one on the trunk. Activities comprised whole body movements as well as gross and dextrous upper-limb activities. Wrist-module data outperformed the other locations for the three activity groups. Specifically, overall classification accuracy rates of almost 93% and more than 95% were achieved for the repeated holdout and user-specific validation methods, respectively, for all 16 activities. Including the altitude profile resulted in a considerable improvement of up to 20% in the classification accuracy for stair ascent and descent. The gyroscopes provided no useful information for activity classification under this scheme. The proposed sensor setting could allow for robust long-term activity monitoring with high compliance in different patient populations.
Highlights
Miniature wearable sensor modules are a promising technology to monitor activities of daily living (ADL) over extended periods of time (Nyan et al 2004), especially for aspects such as activity levels (Bouten et al 1997), changes in habits (e.g. mental/physical decline in the elderly population (Hao & Foster 2008)), or functional recovery outside the clinical environment (Uswatte et al 2000)
Wearable sensor modules are a promising technology to monitor activities of daily living over extended periods of time. To assure both user compliance and meaningful results, the selection and placement site of sensors requires careful consideration. We investigated these aspects for the classification of 16 activities of daily living (ADL) in 6 healthy subjects under laboratory conditions using ReSense, our custom-made inertial measurement unit enhanced with a barometric pressure sensor used to capture activity-related altitude changes
This paper investigated the optimal sensor selection and placement site for activity classification
Summary
Miniature wearable sensor modules are a promising technology to monitor activities of daily living (ADL) over extended periods of time (Nyan et al 2004), especially for aspects such as activity levels (Bouten et al 1997), changes in habits (e.g. mental/physical decline in the elderly population (Hao & Foster 2008)), or functional recovery (e.g. following orthopedic or neurological injury) outside the clinical environment (Uswatte et al 2000). In order to determine the overall activity level and independence of subjects/patients in their home environment, being able to identify and discriminate stair ascent and descent is a key aspect. A detailed analysis of level walking and stair ascent/descent is needed to evaluate subject’s function/dysfunction during daily activities (Coley et al 2005). The presence of stair ascent but absence of stair descent can be an indicator of fear of falling in the elderly population (Butler et al 2009)
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