# Smart Helmet and Insole Sensors for Near Fall Incidence Recognition during Descent of Stairs
## 3 Results
### Results of Head Movement Analysis (Smart Helmet)  
Figure 12 shows the results of _SVM_ data collected from the Smart Helmet during stair descent. Out of the five steps taken down the stairs on each foot, the middle three steps were analyzed; three peak plantar pressure values from each foot were temporally matched with the _SVM_ data of the head movements.  
In E1 and E2, the head movement pattern and the plantar pressure changes were well-matched bilaterally, but in E3, the head movements were visibly different according to bilaterally different leg movements (Smart Shoe data) as a near fall was simulated.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & & \multicolumn{2}{c}{**E1**} & \multicolumn{2}{c}{**E2**} & \multicolumn{2}{c}{**E3**} \\ \hline
**Side** & **Ch. No.** & **Right** & **Left** & **Right** & **Left** & **Right** & **Left** \\ \hline \multirow{8}{*}{Lateral} & 2 & 5.24 & 5.37 & 5.27 & 5.39 & 5.36 & 5.38 \\  & 3 & 5.05 & 5.07 & 5.08 & 5.09 & 5.12 & 5.06 \\  & 5 & 5.03 & 5.20 & 5.22 & 5.22 & 5.08 & 5.19 \\  & 6 & 5.01 & 4.28 & 4.36 & 4.36 & 5.07 & 4.28 \\  & 9 & 4.91 & 4.65 & 4.93 & 4.70 & 4.96 & 4.64 \\  & Sum & 25.24 & 24.57 & 25.36 & 24.76 & 25.59 & 24.55 \\  & SD & 0.12 & 0.44 & 0.37 & 0.42 & 0.15 & 0.44 \\ \hline \multirow{8}{*}{Medial} & 1 & 5.14 & 4.99 & 5.21 & 5.02 & 5.34 & 4.94 \\  & 4 & 5.08 & 5.12 & 5.10 & 5.13 & 5.12 & 5.11 \\ \cline{1-1}  & 8 & 4.28 & 5.05 & 4.34 & 5.06 & 4.36 & 5.05 \\ \cline{1-1}  & 10 & 4.84 & 4.86 & 4.89 & 4.88 & 4.93 & 4.86 \\ \cline{1-1}  & Sum & 19.34 & 20.02 & 19.54 & 20.09 & 19.75 & 19.96 \\ \cline{1-1}  & SD & 0.39 & 0.11 & 0.39 & 0.11 & 0.42 & 0.11 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Results of mediolateral plantar pressure distribution in each condition (unit: pF).  
Figure 11: Results of mediolateral plantar pressure distribution in each foot under each condition (all subjects). E1: Natural descent, E2: Weighted descent, E3: Near fall-simulated descent.  
Table 5 and Figure 13 present the results of _SVM_ data collected from the Smart Helmet under each experiment condition. The highest head tilt movement at the time of foot contact during stair descent was found in E3 in the right foot (\(2.31\pm 0.28\) g). The second highest head tilt was observed in E1 in the right foot (\(2.10\pm 0.25\) g).  
\begin{table}
\begin{tabular}{c c c c c c c} \hline  & \multicolumn{2}{c}{**E1**} & \multicolumn{2}{c}{**E2**} & \multicolumn{2}{c}{**E3**} \\ \hline
**Sub No.** & **Right** & **Left** & **Right** & **Left** & **Right** & **Left** \\ \hline
1 & 2.06 & 2.06 & 2.08 & 2.11 & 2.41 & 1.27 \\
2 & 2.26 & 2.26 & 2.26 & 2.26 & 2.35 & 1.11 \\
3 & 2.12 & 1.98 & 1.99 & 1.86 & 2.26 & 1.24 \\
4 & 2.16 & 1.99 & 1.95 & 1.95 & 2.26 & 1.49 \\
5 & 2.36 & 2.22 & 2.06 & 2.05 & 2.70 & 1.55 \\
6 & 2.12 & 2.23 & 2.34 & 2.32 & 2.57 & 1.04 \\
7 & 1.46 & 1.46 & 1.31 & 1.40 & 1.65 & 1.36 \\
8 & 2.33 & 2.35 & 2.31 & 2.35 & 2.40 & 1.19 \\
9 & 2.13 & 2.12 & 1.89 & 1.97 & 2.26 & 1.13 \\
10 & 2.03 & 2.22 & 2.03 & 2.37 & 2.29 & 1.47 \\ \hline AVG & 2.10 & 2.09 & 2.02 & 2.06 & 2.31 & 1.29 \\ SD & 0.25 & 0.25 & 0.30 & 0.29 & 0.28 & 0.18 \\ \hline \end{tabular}
\end{table}
Table 5: Results of _SVM_ data from Smart Helmet matched with Smart Shoe data (unit: g).  
Figure 12: Matched analysis of Smart Helmet acceleration values and Smart Shoe plantar pressure values in each foot.