# Human-Robot Interaction for Improving Fuselage Assembly Tasks: A Case Study
## 5 Conclusions  
In this study, the potential benefits of HRI was investigated for a real aerospace application. In particular, a methodology for redesigning a workstation was introduced and a real case study, in which a composite fuselage panel is assembled by human and robots, was proposed. The safety requirements and constraints imposed by standard ISO 10218 and ISO/TS 15066 were considered. In order to verify the feasibility of the approach, a simulation was carried out to evaluate the performance of the workstation in terms of both working times and ergonomics.  
The results show a significant improvement of assembling performances in HRI configuration: in fact, the total assembling time is reduced of 47.6% with respect to the same activity manually  
\begin{table}
\begin{tabular}{c c c} \hline \hline  & \multicolumn{2}{c}{**OWAS Risk Index**} \\ \hline
**Value** & **Risk Exposure** & **Consequences** \\ \hline
100 & Norisk & No consequences \\
101–200 & Low risk & If possible, improve structural factors or take other \\  & & organizational measures \\
201–300 & Medium risk & Improve structural factors or take other organizational \\  & & measures, rapidly \\
301–400 & High risk & Immediate action need to change the operating methods, \\  & & the equipment used or the work positions of the workers \\ \hline \hline \end{tabular}
\end{table}
Table 6: OWAS index—risk areas.  
\begin{table}
\begin{tabular}{c c c c} \hline
**Action Category** & **\# of Observations** & **Observations Frequencies** & **\% Value** \\ \hline
1 & 114,983 & a & 93.885\% \\
2 & 4840 & b & 3.951\% \\
3 & 2649 & c & 2.163\% \\
4 & 0 & d & 0.000\% \\ \hline  & 122,472 & **Total** & 100\% \\ \hline \hline \end{tabular}
\end{table}
Table 7: Simulation results—OWAS coefficients.  
performed. Concerning ergonomics, the OWAS index was evaluated and the result demonstrate that HRI allows the human working in extreme safety conditions, in terms of risk of work-related injuries. Unfortunately, it has not been possible to compare the obtained results with those of the OWAS index in the case of manual processing. However, it is presumable that, in this last case, the values are higher, considering the difficulty in reaching the working areas and the application of forces, together with the handling of additional loads, especially in performing drilling operations.  
Numeric results validation, by means of comparison with experimental results, is not possible since the physical workstation is still not available. However--as already previously described--the literature demonstrated that numeric models for simulating manual operations provide results in agreement with those ones provided by experimental tests [11; 12; 13; 14; 15].  
Future developments may be focused on the optimization of the sequence of tasks of the working cycle in order to assess the maximum benefits which can be obtained by employing the HRI solution. Computational time of the simulation can also be optimized by finding a tradeoff between the number of acquisition needed and the quality of the ergonomic assessment.  
Conceptualization, A.G., M.C., E.L., M.F.; methodology, A.G., M.C., M.F.; software, A.G., M.C., E.L., M.F.; data curation, A.G, M.C.; writing--original draft preparation, A.G., M.C., E.L.; writing--review and editing A.G., M.C., E.L., M.F.; visualization, A.G., M.C., E.L.; supervision, M.F.; project administration, M.F.; All authors have read and agreed to the published version of the manuscript.  
This work was supported by the European Commission under the H2020 Framework Clean Sky JTI-project LABOR, ID no. 785419, topic manager: Leonardo SpA.  
No conflict of interest to declare.