# Ergonomic Assessment of Physical Load in Slovak Industry Using Wearable Technologies
## 3 Results
For each file, we tested the null hypothesis: \"The sample distribution is normal.\" If the \(p\)-value is less than the significance level \(\alpha\), the null hypothesis is rejected, and the distribution is non-normal. Because the \(p\)-value < \(\alpha\) for each sample set, we rejected the null hypothesis of normality of the individual base sets. Therefore, we used a nonparametric Wilcoxon pairwise test for pairwise comparisons. The null hypothesis is H\({}_{0}\): m\({}_{1}\) = m\({}_{2}\), meaning \"the medians of both sets are the same,\" and the alternative hypothesis is H\({}_{1}\): m\({}_{1}\) \(\
eq\) m\({}_{2}\), meaning \"the medians of both sets are not the same.\" The resulting \(p\)-values from pairwise tests are in \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Joint/Mean x [\%]** & \multicolumn{2}{c}{**Green Area**} & \multicolumn{2}{c}{**Orange Area**} & \multicolumn{2}{c}{**Red Area**} \\ \hline
**Condition** & **STAND** & **EXO** & **STAND** & **EXO** & **STAND** & **EXO** \\ \hline Neck & 55.5 & 66.7 & 34.1 & 26.7 & 10.4 & 6.5 \\ Lower Back & 93.1 & 95.9 & 6.8 & 4.1 & 0.1 & 0.0 \\ Right Shoulder & 72.8 & 72.0 & 18.6 & 19.0 & 8.6 & 9.0 \\ Left Shoulder & 77.7 1 & 61.1 1 & 15.9 1 & 26.7 1 & 6.4 & 8.6 \\ Right Hip & 94.6 & 83.7 & 5.4 & 8.0 & 0.0 & 8.2 \\ Left Hip & 89.71 & 72.8 1 & 10.1 1 & 21.0 1 & 0.2 & 6.21 \\ \hline \hline \end{tabular}  
* Values with significant impact on results.  
\end{table} 
Table 4: Verification of measured motion data file normality is performed using the Shapiro-Wilk normality test. For each file we tested the null hypothesis: “The sample distribution is normal.” If the \(p\)-value was less than the significance level \(\alpha\), then the null hypothesis was rejected and the distribution was non-normal. Figure 4: Detailed results of time duration in individual postures, in experiments with one worker using exoskeleton: Neck Flexion/Extension. Table 5. The null hypothesis was rejected in cases where the \(p\)-value was lower than the level of significance (\(p\)-value \(<\alpha\)). The test results show statistically significant differences in the case of Left Hip in green and orange areas, Left Shoulder in green and orange areas for all tested subjects (\(p\)-value \(<\alpha\)). It turns out that between the using/eventually not using the exoskeleton in cases Left Hip green, orange, and red areas and Left Shoulder green and orange areas in all tested subjects, there are statistically significant differences. It means that using the exoskeleton brings some ergonomic improvements. In summary of all data obtained from the experiments with four workers after statistical evaluation, we obtained the following average results. The neck seemed to be a critical body segment in the monitored task. The neck's motion was mostly in the green zone (55.5%), except with worker one, but a high time was spent in the red area (10.4%); the worst situation was in neck flexion/extension. The situation was significantly improved while using the exoskeleton; the neck was in the green zone for 66.7%, the orange zone dropped down to 26.7%, and the red from 10.4% to 6.5% (see Table 4). The lower back was in the optimal green zone almost the entire time (93.1% STAND measurement and 95.9% EXO measurement); the red zone was eliminated when using the exoskeleton (see Table 4). The right and left shoulders mostly worked in the green zone (more than 70%); however, during work with the exoskeleton, the situation brought higher risk, and the time spent in the orange zone increased for the right shoulder from 18.6% to 19.0%, and for left one from 15.9% to 26.7%. Additionally, significant time was spent in the red zone--right shoulder 8.6% and even with the exoskeleton 9.0%, left shoulder 6.4% and 8.6% with the exoskeleton. The worst situation was identified in horizontal internal/external rotation for both shoulders. The reason for that might be the working table height.