Algorithm 1 Body Acceleration Vector Extraction.

Input: 1. Low-pass filter coefficient $\alpha$ 2. Total acceleration measurement vector ($TotalAc{c}_x$,$TotalAc{c}_y$,$TotalAc{c}_z$) 3. Gravity vector ($Gravit{y}_x$,$Gravit{y}_y$,$Gravit{y}_z$) Output: Body acceleration ($BodyAc{c}_x$,$BodyAc{c}_y$,$BodyAc{c}_z$) If Total acceleration measurement vector update $Gravit{y}_x$ = $\alpha$ * $Gravit{y}_x$ + (1−$\alpha$) * $TotalAc{c}_x$ $Gravit{y}_y$ = $\alpha$ * $Gravit{y}_y$ + (1−$\alpha$) * $TotalAc{c}_y$ $Gravit{y}_z$ = $\alpha$ * $Gravit{y}_z$ + (1−$\alpha$) * $TotalAc{c}_z$ $BodyAc{c}_x$ = $TotalAc{c}_x$ − $Gravit{y}_x$ $BodyAc{c}_y$ = $TotalAc{c}_x$ − $Gravit{y}_x$ $BodyAc{c}_z$ = $TotalAc{c}_x$ − $Gravit{y}_x$