## 4 Results
### Ossite Welding Results
#### 4.2.1 Objective Measures  
The analysis rejected the null hypothesis (H0) that the MRVF visual/haptic HRI approach for intuitive tele-welding, the MRnoVF, and 2D baseline modules have identical effects on welder performance. In particular, the results show that the MRVF visual/haptic HRI approach significantly outperformed both the 2D baseline and MRnoVF HRI methods on the welding tasks for all pairwise comparisons. Guiding a welding robot using natural  
Figure 8: Boxplots of quantitative measures in the X and Z directions for variance (**a**) and RMSE (**b**) of the users’ torch hand motions for both professional and unskilled welders in the onsite welding experiment. The special symbols (circles and asterisks (”)) are outliers in the data, representing that they are outside of a certain range indicated by the boxes in the box plot. The numbers next to the circles and asterisks indicate which observations in the dataset are outliers. Figure 9: Results of the MR-integrated visual/haptic tele-welding system from a professional welder (**above**) and unskilled welder (**below**). welding motion through MR with hybrid guidance/prevention VFs in the MR workspace improved remote welding performance and reduced novice, unskilled welder effort. As shown in Figure 10a, a one-way within-subjects ANOVA with repeated measures and a Greenhouse-Geisser correction indicated the time taken to position the torch to the desired welding pose was statistically significantly different--F (1.866, 27.995) = 47.279, \(p\) < 0.001, Partial = 0.76. The post-hoc test revealed the time to position the torch decreased significantly with the MRVF (M = 18.60) compared to the MRnoVF module (M = 42.32) and the baseline module (M = 46.72). Torch alignment times for the welding tasks using the MRVF-integrated visual and haptic tele-welding framework were reduced by 56% and 60% compared to the MRnoVF and baseline cases, respectively, indicating that the typical 2D tele-welding module and the MRnoVF case require additional time to achieve the same capabilities as the proposed MR-integrated visual/haptic HRI module. Statistical significance was also seen for the average number of collisions between the three HRI modules--F (1.424, 21.353) = 4.091, \(p\) < 0.05, Partial = 0.21. The pairwise comparisons indicated the mean collision numbers to complete the welding task were significantly reduced in the baseline (M = 0.50) compared to the MRnoVF module (M = 0.25) and the MRVF module (M = 0), as shown in Figure 10b. The statistical results demonstrate that following through the cone-shaped guidance fixture provided by the MRVF can reduce the welding completion time by minimizing the time used for navigating the torch tip to the initial welding pose. In addition, the prevention VF greatly reduced the likelihood of a collision occurring. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**Baseline**} & \multicolumn{2}{c}{**MRnoVF**} & \multicolumn{2}{c}{**MR**} \\ \hline
**Measure** & **Mean** & **Std. Dev** & **Mean** & **Std. Dev** & **Mean** & **Std. Dev** \\ \hline Time & 46.72 & 8.75 & 42.32 & 11.40 & 18.60 & 5.37 \\ Collisions & 0.50 & 0.73 & 0.25 & 0.45 & 0.00 & 0.00 \\ Mental Demand & 80.31 & 9.41 & 75.31 & 10.08 & 45.00 & 15.71 \\ Physical Demand & 77.94 & 16.02 & 74.44 & 10.58 & 32.25 & 13.87 \\ Temporal Demand & 78.00 & 15.56 & 73.44 & 13.15 & 66.81 & 11.36 \\ Performance & 64.75 & 24.33 & 78.50 & 11.80 & 43.88 & 18.06 \\ Effort & 78.94 & 14.36 & 63.56 & 19.43 & 34.38 & 10.78 \\ Frustration & 92.81 & 5.47 & 69.94 & 12.92 & 38.31 & 11.46 \\ Average Workload & 78.79 & 5.80 & 72.53 & 5.13 & 43.44 & 4.86 \\ Usefulness & 2.25 & 0.78 & 2.69 & 1.08 & 4.19 & 1.42 \\ Ease of Use & 2.63 & 1.03 & 3.13 & 0.96 & 5.50 & 0.82 \\ TAM & 2.44 & 0.48 & 2.91 & 0.78 & 4.85 & 0.77 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Mean values and standard deviations of all objective and subjective measurements.