# Evaluating the Efficacy of a Passive Exoskeleton for Enhancing Ergonomics in Manufacturing
## 3 Results and Discussion
### Interaction Effect Analysis Using ANOVA  
An ANOVA model was developed to investigate the effects of task, support, and body part, as well as their two-way interactions, on PPE. This analysis (Table 4) confirmed the previous results regarding the significant effects of all main factors and adds new insights into their interactions. The interaction between task and support demonstrated an F-ratio of 3.95, suggesting that the impact of support varied depending on the task performed. The task and body part interaction, with an F-ratio of 4.22, indicated that the exertion felt differed by body part depending on the specific task, emphasizing the role of task specificity on physical exertion. Additionally, the interaction between support and body part, with an F-ratio of 4.21, implies that the effectiveness of exoskeleton support varied across different body parts.  
These results collectively underscore the complex dynamics between task types, support mechanisms, and body part engagement, which are crucial for designing ergonomic interventions and optimizing task allocation in work settings to minimize physical strain and enhance performance efficiency.  
Parameter Estimate from the Two-Way ANOVA Model  
The detailed parameter estimates for each factor, their levels, and interactions resulting from the two-way ANOVA model are shown in Appendix B. The results with statistical significance are summarized in Table 5. The task-related effects showed that both Task C (carrying) and Task L (lifting) increased exertion significantly compared to the baseline exertion of walking, with lifting being slightly more demanding than carrying. The support from the exoskeleton (Support [Ex]) significantly reduced the perceived exertion by 3.8500 units, indicating its effectiveness in alleviating physical strain. Regarding the body parts, the lower back and knee reported higher exertion levels than other body parts, with  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Source** & **DF** & **Sum of Square** & **F Ratio** & _p-Value_ \\ \hline Task & 2 & 1812.1333 & 56.64 & \textless{}0.0001 * \\ Support & 1 & 889.35000 & 55.59 & \textless{}0.0001 * \\ Body part & 9 & 2344.4833 & 16.28 & \textless{}0.0001 * \\ Task \(\times\) Support & 2 & 126.4000 & 3.95 & \textless{}0.0378 * \\ Task \(\times\) Body part & 18 & 1216.866 & 4.22 & \textless{}0.0046 * \\ Support \(\times\) Body part & 9 & 605.816 & 4.21 & \textless{}0.0019 * \\ \hline \hline \end{tabular}  
* Corresponding _p_-value is less than \(\alpha=0.05\), showing statistical significance.  
\end{table}
Table 4: Two-way ANOVA for the effects of task, support, body part on PPE.  
Figure 8: Participants’ average sum of PPE per body part when walking with and without the exoskeleton.  
the lower back showing the most significant increase. Conversely, the exertion levels for the ankle, elbow, feet, and neck were significantly lower, which might reflect less strain or different kinds of movements involving these parts during the tasks. The interaction effects also highlight interesting dynamics between support and body parts. Specifically, the exoskeleton provided additional benefits when interacting with the chest area, reducing exertion further by 5.3500 units. In addition, its interaction with the lower back was even more noteworthy, reducing exertion by 7.4833 units, indicating a targeted effectiveness at this common part of strain. Task-specific interactions further revealed that carrying a box increased exertion in both the lower and the upper back significantly. Similarly, lifting a box also elevated the exertion in the lower back. These findings underscore the complex interplay between task type, ergonomic support, and anatomical impacts, suggesting that exoskeleton design and task adjustments should be considerate of specific body part vulnerabilities and task demands to optimize worker health and productivity. The full results with all variables and interactions are included in Appendix B, Table A2.