## 4 Feasibility Validation of the QCES System
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**RMSEs**} & \multicolumn{8}{c}{**Limb Parts**} \\ \cline{2-13}  & \multirow{2}{*}{**Neck**} & \multirow{2}{*}{**Waist**} & \multirow{2}{*}{**Left Leg**} & \multirow{2}{*}{**Left Upper Arm**} & \multicolumn{2}{c}{**Left Proper Arm**} & \multirow{2}{*}{**Left Proper Arm**} & \multirow{2}{*}{**Left Wrist**} & \multirow{2}{*}{**Right Leg**} & \multirow{2}{*}{**Right Upper**} & \multirow{2}{*}{**Right**} & \multirow{2}{*}{**Right**} & \multirow{2}{*}{**Average**} \\  & & & & & & & & & & & & \\ \hline M1-45 & 7.56 & 6.06 & 17.96 & 5.47 & 3.80 & 1.44 & 2.21 & 6.35 & 4.79 & 4.15 & 5.98 \\ M1-60 & 3.22 & 12.22 & 12. In the previous sections, this study verified the consistency of the QCES system in capturing data for 10 limb angles compared to the data captured by the OptiTrack motion capture system. In the evaluation results, this study separately calculated the average scores of three experts and the QCES system for the final REBA scores, scores A and B, and RULA final scores, scores A and B, as benchmarks for subsequent validation. As shown in Figure 9, bar charts and independent sample \(t\)-tests were used to demonstrate the comparison between the expert ratings on the final REBA and RULA scores and the QCES system's capture. The results in the figure indicate significant differences in the REBA scores for postures M2-60 and M2-90 (\(p<0.01\)), and significant differences in the RULA scores for posture M2-60. However, the scores for other postures are consistent with the expert assessments. As shown in Table 4, it is evident that there is a \"strong\" consistency between the QCES system proposed in this study and the experts in terms of the REBA and RULA assessment scores (\(p<0.01\), \(0.664<\) kappa \(<0.894\), with an average RMSE value of 0.368). Therefore, this study can demonstrate that the QCES system can perfectly replace expert scoring in outputting assessment results and rapidly generate assessment results comparable to those of experts. This also confirms the validity of hypothesis H2. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Title 1** & **RMSE** & **Cohen’s Kappa** & \(p\)**-Value** \\ \hline RE-Grand Score & 0.471 & 0.712 & \textless{}0.01 \\ RE-Score A & 0.471 & 0.664 & \textless{}0.01 \\ RE-Score B & 0.408 & 0.793 & \textless{}0.01 \\ RU-Grand Score & 0.236 & 0.894 & \textless{}0.01 \\ RU-Score A & 0.236 & 0.866 & \textless{}0.01 \\ RU-Score B & 0.624 & 0.665 & \textless{}0.01 \\ \hline Average & 0.408 & 0.766 & \\ \hline \hline \end{tabular}  
* RE represents the REBA assessment method. RU represents the RULA assessment method.  
\end{table} 
Table 4: Comparing linearly weighted Cohen kappa and RMSE, the consistency between QCES system and expert evaluation results was observed. Figure 9: Comparison of QCES system and experts in the final scores of REBA and RULA, ***:** significant difference (\(p<0.01\)). In the previous sections, the accuracy of the QCES system in assessing WMSDs was thoroughly validated. Therefore, this study utilized the assessment data from the QCES system to visually demonstrate the scores of different tilt angles of waste containers in the REBA and RULA assessment methods using bar charts, as shown in Figure 10. When waste collectors retrieve garbage from waste containers positioned at a 90\({}^{\circ}\) tilt angle perpendicular to the ground, both the REBA and RULA assessments indicate a moderate risk of WMSDs, necessitating further investigation and posture modification. However, after modification, the tilt angles of the waste containers at 45\({}^{\circ}\) and 60\({}^{\circ}\) show significant improvement in the workers' postures, leading to a significant reduction in WMSD risk. Particularly, the waste containers with a 45\({}^{\circ}\) tilt angle are assessed as having a low WMSD risk.