# Implementation and Evaluation of Dynamic Task Allocation for Human-Robot Collaboration in Assembly
## 3 Results
### Efficiency
#### 3.2.1 Assembly Process Time  
An overview of the resulting mean assembly process times for the different task allocation modes is given in Table 4, clustered by the number of components and the duration of the delay. As follows the assembly process times for one component from Table 4, the execution of the assembly in human-robot collaboration reduces the cycle time in the user study by 19.2% in dynamic mode and 20.4% in static mode compared to manual assembly. For the assembly of one component, the assembly process times for the static and dynamic task allocation mode are similar. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multicolumn{1}{c}{(a)} & \multicolumn{2}{c}{(b)} & \multicolumn{2}{c}{(c)} & \multicolumn{2}{c}{(d)} & \multicolumn{2}{c}{(e)} \\ \multicolumn{1}{c}{**Gender**} & \multicolumn{2}{c}{**Age**} & \multicolumn{2}{c}{**Vocational Education**} & \multicolumn{2}{c}{**Experience**} & \multicolumn{2}{c}{**Technical Affinity**} \\ \hline F & 25\% & 20–24 & 40\% & Academic & 50\% & Assembly & 60\% \({}^{1}\) & ATI score \\ M & 75\% & 25–29 & 40\% & Undergraduate & 50\% & Assistance systems & 40\% \({}^{1}\) & 4.74 \(\pm\) 0.68 \\ N/D & \(-\)/\(-\) & 30–34 & 10\% & & & Collaborative robots & 25\% \({}^{1}\) & \\  & & 35–49 & 10\% & & & & & \\ \hline \hline \end{tabular} \({}^{1}\) Subjects with response of 4 or higher on 5-level Likert scale.  
\end{table} 
Table 3: Demographic and experience data for the subjects in the user study: (a) gender information; (b) age information; (c) vocational education information; (d) previous experience in manual assembly, use of assistance systems in industrial contexts, and programming or working with collaborative robots; (e) technical affinity information. Figure 17: Exemplary Gantt charts for assembly process in different task allocation modes: (**a**) assembly of one component with 90 s human delay; (**b**) assembly of three components with 90 s human delay. The potentials of dynamic task allocation only take effect when the degree of parallelism of the overall process is higher, i.e., when three components were assembled in the study. The process time decreases by 10.2% on average compared to static task allocation with optimized planning and by 11.7% on average in comparison to static-asymmetric task allocation (i.e., with an intuitive, simple planning of the task assignment), when using dynamic task allocation. This relationship also becomes evident from the graphical illustration in Figure 18.  
The effects of the duration of delays in the different task allocation modes are shown in Figure 19 for the assembly of three components. In general, the total process time increases with increasing delay duration in all modes. The delay was set at the beginning of the parallel sequences of the total process in all runs (cf. Figure 17). Due to the limited number of subjects per delay group, however, no reliable statement can be drawn here about the ability of the different task allocation modes to compensate for delays in terms of cycle time, and thus remains a subject for future research. \begin{table}
\begin{tabular}{c c c c c c} \hline  & & & \multicolumn{3}{c}{**Process Time in s**} \\ \hline
**Task Allocation Mode** & **Components** & **Delay = 0 s** & **Delay = 30 s** & **Delay = 60 s** & **Delay = 90 s** \\ \hline Manual & & 192.6 \(\pm\) 55.4 & 254.0 \(\pm\) 6.7 & 251.4 \(\pm\) 49.2 & 279.6 \(\pm\) 50.2 \\ Static & 1 & 153.0 \(\pm\) 7.3 & **183.2 \(\pm\) 31.0** & 209.6 \(\pm\) 9.9 & **233.6 \(\pm\) 17.4** \\ Dynamic & & **152.0 \(\pm\) 37.7** & 191.0 \(\pm\) 18.6 & **208.2 \(\pm\) 3.5** & 241.6 \(\pm\) 24.8 \\ Static (asymmetric) & & 431.6 \(\pm\) 78.1 & 442.8 \(\pm\) 73.5 & 477.0 \(\pm\)55.5 & 510.8 \(\pm\) 60.6 \\ Static & 3 & 452.8 \(\pm\) 108.6 & 484.0 \(\pm\) 72.7 & 427.6 \(\pm\) 25.9 & 467.2 \(\pm\) 63.5 \\ Dynamic & & **363.4 \(\pm\) 69.0** & **422.2 \(\pm\) 57.5** & **410.6 \(\pm\) 28.8** & **447.6 \(\pm\) 35.6** \\ \hline \end{tabular}
\end{table}