# A Human-Inspired Control Strategy for Improving Seamless Robot-To-Human Handovers
## 3 Results and Discussion
### Evaluation of the Robotic Impedance Control Based on the HRH

Table 2: Comparisons of the average interactive force (\(F_{int}\)) and time (\(t\)) parameters, while varying both damping factor (\(B_{d}\)) and spring stiffness (\(K_{d}\)). Figure 9: Survey responses for the human–robot handover tasks. impedance parameters made up of \(K_{d}\) (50), \(B_{d}(75)\) and \(M_{d}(0.25)\), more than those of the first set. Finally, the results of the robotic dynamic response based on the hybrid PID position and impedance control in the robot-to-human handovers were carried out and then compared with the outcomes of the HHH. Figure 10 shows an example of a comparison between the interactive force profiles against time from the HHH and HRH tests. It can be concluded that the quantitative measurement of the performance of robot behavioural control can be considered acceptable for object handover interaction with a human receiver. It provided effective performance during the natural cooperative tasks, where the robot was able to successfully pass the object to the human in a safe, reliable and timely manner. However, after careful analysis with regard to the HRH results, the robot has to perform a slightly longer handover period than that of the HHI, even though the maximum forces from both cases are similar. This is because the robot control algorithm was initially designed to ensure its safe and natural operational characteristics specifically while physically releasing the object to the receiver. Then, this might result longer object handover process. Figure 10: Interactive force profiles against the time of (**a**) the HHH test and (**b**) the HRH test. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & & \multicolumn{5}{c}{**Paired Samples Statistics**} \\ \hline \multirow{3}{*}{Pair 1} & \multicolumn{2}{c}{Mean} & \multicolumn{1}{c}{N} & \multicolumn{1}{c}{SD} & \multicolumn{1}{c}{SD Error Mean} \\ \cline{2-7}  & \multicolumn{1}{c}{Impedence1} & \multicolumn{1}{c}{3.80} & \multicolumn{1}{c}{20} & \multicolumn{1}{c}{0.768} & \multicolumn{1}{c}{0.172} \\ \cline{2-7}  & \multicolumn{1}{c}{Impedence2} & \multicolumn{1}{c}{4.20} & \multicolumn{1}{c}{20} & \multicolumn{1}{c}{0.616} & \multicolumn{1}{c}{0.138} \\ \hline \multicolumn{7}{c}{**Paired Samples Correlations**} \\ \hline \multicolumn{7}{c}{N} & \multicolumn{2}{c}{Correlation} & \multicolumn{2}{c}{Sig.} \\ \hline Pair 1 & \multicolumn{2}{c}{Impedence1 \& Impedence2} & \multicolumn{1}{c}{20} & \multicolumn{1}{c}{0.757} & \multicolumn{1}{c}{0.000} \\ \hline \multicolumn{7}{c}{**Paired Samples Test**} \\ \hline \hline \multirow{3}{*}{Pair 1} & \multicolumn{2}{c}{Paired Differences} \\ \cline{2-7}  & \multirow{3}{*}{Mean} & \multirow{3}{*}{SD} & \multicolumn{1}{c}{SD Error Mean} & \multicolumn{1}{c}{95\% Confidence of the Difference} & \multirow{3}{*}{t} & \multirow{3}{*}{df} & Sig. (2-tailed) \\ \cline{3-3} \cline{5-7}  & \multicolumn{1}{c}{} & \multicolumn{1}{c}{Mean} & \multicolumn{1}{c}{Lower} & \multicolumn{1}{c}{Upper} & \multirow{3}{*}{} & \multirow{3}{*}{0.002} \\ \hline \multirow{3}{*}{Pair 1} & \multicolumn{2}{c}{Impedence1 \& Impedence2} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} \\ \cline{3-3} \cline{5-7}  & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} \\ \hline \hline \end{tabular}
\end{table} 
Table 3: T-test results of the comparison between the parameter set 1 and 2. Consequently, it can be concluded that understanding kinematically and dynamically how two humans physically collaborate while naturally performing object handover tasks offers the effective performance and reliability of the robot-to-human handover procedure and acceptable HRI implementation. This was in agreement with the parallel test outcomes, demonstrating significant satisfaction with the overall performance of the HRH system, as measured by an average rating of 4.20 on a five-point scale.