## 3 Results
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & & \multicolumn{4}{c}{**RMSE RGB-MAS vs. Manual [\({}^{\circ}\)]**} & \multicolumn{4}{c}{**RMSE Vicon vs. Manual [\({}^{\circ}\)]**} \\ \cline{2-10}  & **T-Pose** & **Seated** & **Standing** & **Reach** & **Pick Up** & **T-Pose** & **Seated** & **Standing** & **Reach** \\ \hline Neck flexion/extension & 9.19 & 13.10 & 19.63 & 6.87 & 28.05 & 8.26 & 15.47 & 8.64 & 8.32 \\ Left shoulder abduction & 6.90 & 44.13 & 7.54 & 49.68 & 8.03 & 7.29 & 7.52 & 13.00 & 38.11 \\ Right shoulder abduction & 6.67 & 47.00 & 7.82 & 51.65 & 7.55 & 6.35 & 6.54 & 7.09 & 38.08 \\ Left shoulder & 32.62 & 53.84 & 12.03 & 82.10 & 30.43 & 21.08 & 16.19 & 19.55 & 101.52 \\ Right shoulder & 50.91 & 50.70 & 70.02 & 71.31 & 28.01 & 23.14 & 15.66 & 21.43 & 110.20 \\ flexion/extension & 3.60 & 15.03 & 14.21 & 36.16 & 15.83 & 6.21 & 7.08 & 15.56 & 16.35 \\ Right elbow & 2.20 & 9.67 & 18.63 & 25.45 & 10.26 & 5.60 & 17.97 & 10.35 & 39.00 \\ Trunk flexion/extension & 3.48 & 30.06 & 5.46 & 20.71 & 33.46 & 3.28 & 33.60 & 4.59 & 17.93 \\ Left knee & 3.81 & 53.12 & 6.82 & 22.73 & 30.10 & 1.98 & 18.85 & 2.68 & 8.39 \\ Right knee & 3.95 & 20.69 & 1.94 & 22.63 & 29.19 & 3.75 & 21.24 & 1.90 & 22.52 \\ flexion/extention & & & & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: RMSE values obtained when comparing RGB-MAS angles with manually extracted ones. Table 5 shows the median RULA values obtained using each angle extraction method considered (i.e., manual measurement, RGB-MAS prediction, Vicon tracking). Table 6 shows the RMSE between the RULAs determined through manual angle measurement, and those calculated from the angles predicted by RGB-MAS and the Vicon system, respectively. The maximum RMSE between RGB-MAS and manual analysis is 1.35, while the maximum Vicon vs. manual RMSE is 1.78. Since the closer a value of RMSE is to zero, the better the prediction accuracy is, it can be observed that RGB-MAS compared to a most used manual analysis is generally able to provide a result closer to that of the Vicon systems. However, this should not be interpreted as a better performance of RGB-MAS than Vicon: the result that can be obtained, instead, is that the values provided by Vicon, in some cases,  
Figure 6: Graph comparing the RMSE values \"RGB-MAS vs. manual\" and “Vicon vs. manual\". Figure 7: Body skeleton predicted by the RGB-MAS. are very different from both those of the RGB-MAS system and those estimated manually. This is because the result of the Vicon system is not affected by estimation errors due to perspective distortions, which instead occur with the other two systems. Ultimately, the RGB-MAS system can provide estimates that are very similar to those obtained from a manual extraction, although the system's accuracy is poor compared to the Vicon. As can be seen from Table 5, the risk indices calculated from the angles provided by the RGB-MAS system, those evaluated from manually measured angles, and those provided by Vicon belong to the same ranges. The only exception can be found for the Reach posture, where the Vicon underestimated the scores of a whole point. Despite the overestimations in angle prediction, the RULA score evaluation made considering the extension of the angles within particular risk ranges filters out noise and slight measurement inaccuracies. This leads to RULA scores that are slightly different in numbers but can be considered almost the same in terms of risk ranges.