# Implementation and Evaluation of Dynamic Task Allocation for Human-Robot Collaboration in Assembly
## 3 Results
### Human Factors and User Satisfaction
#### 3.3.2 General Assessment of the System  
In Table 6, an overview of the resulting scores measured for general system assessment, i.e., system usability, information quality, trust in robot, and the subjects' feedback about their willingness for permanent usage of the system for collaborative assembly are given.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Data** & **Manual** & **Static (Asymmetric)** & **Static** & **Dynamic** \\ \hline NASA RTLX score – (adjective rating) & 17.7 \(\pm\) 7.1 & 12.5 \(\pm\) 2.6 & 11.3 \(\pm\) 4.1 & 18.5 \(\pm\) 7.6 \\ Fluency score \({}^{\star}\) & - & 3.5 \(\pm\) 0.9 1,2 & 3.5 \(\pm\) 0.8 1,2 & 3.7 \(\pm\) 0.8 1,2 \\ Satisfaction score \({}^{\star}\) & - & 3.6 \(\pm\) 0.6 1 & 3.9 \(\pm\) 0.4 1 & 4.4 \(\pm\) 0.2 1 \\ \hline \hline \end{tabular}  
* Mean response on 5-level Likert scale. 2 The point value of questions with a reversed scale was reversed for uniformity and consistency of the score. \({}^{\star}\) Higher value indicates better score. \({}^{\star}\) Lower value indicates better score.  
\end{table}
Table 5: Assessment results for workload, fluency, and satisfaction for the different task allocation modes.  
Figure 21: Detailed assessment of fluency and satisfaction in spider diagrams. (**a**) Fluency assessment. Questions with reversed scales were worded positively for illustration in spider diagram and the point value was reversed. (**b**) Satisfaction assessment.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \begin{tabular}{c} **(a)** \\ **Usability** \\ \end{tabular} & \begin{tabular}{c} **(b)** \\ **Quality of Provided Information** \\ \end{tabular} & \begin{tabular}{c} **(c)** \\ **Permanent Use of System 2** \\ \end{tabular} & \begin{tabular}{c} **(d)** \\ **Trust** \\ \end{tabular} \\ \hline \begin{tabular}{c} SUS score \\ \end{tabular} & 79.4 \(\pm\) 12.5 & \begin{tabular}{c} Correctness and \\ completeness \\ \end{tabular} & 4.5 \(\pm\) 0.9 1 & Yes & 85 \% \\ Acceptability & Acceptable & Relevance and timing & 4.25 \(\pm\) 0.8 1 & No & 5 \% \\ \multirow{2}{*}{\
\begin{tabular}{c} Adjective rating \\ \end{tabular} } & \multirow{2}{*}{Good} &
\begin{tabular}{c} Understandability and \\ comprehensibility \\ Easy and quick \\ information extraction \\ \end{tabular} & 4.2 \(\pm\) 1.0 1 & Not sure & 10 \% \\ \hline \hline \end{tabular}  
* \({}^{1}\) Mean response on 5-level Likert scale. 2 Subjects’ response to question ”Would you use the system permanently?”.  
\end{table}
Table 6: General system assessment: (a) system usability; (b) quality of provided information; (c) subjects’ readiness for permanent system usage; (d) trust in robot.  
The developed system achieves an SUS score of 79.4, which is interpreted as a grade A\({}^{-}\), i.e., a good system usability (see [61]). The quality of provided information achieves high feedback in terms of accuracy, relevancy, and representation. Despite an acceptable score, needs for improvement were identified in the ease of information extraction. This was also mentioned by some subjects in the suggestions for improvement.  
In terms of trust in the robot, a high score of 43.3 was achieved. According to [59], this is an almost optimal trust result, as the score is high, but not too close to the maximum value of 50, which would indicate that the subjects are overly relying on the robot, potentially leading to complacency.  
Finally, this positive overall assessment of the developed system was further confirmed by the statement of 85% of the subjects who can envision a permanent use of the system for collaborative assembly, indicating a good system acceptance.