## 4 Experiment
### Result
#### 4.5.1 External Torque  
The external torque measured at the hip, knee, and ankle joints are presented in Table 3, and the external torque measured at the hip joint is depicted in Figure 11. The yellow area represents phase I of the STS transfer. According to Figure 11a, when using the correct method of providing standing assistance, a negative external torque value was necessary to flex the hip joint in phase I of the STS transfer, whereas a positive external torque value was necessary to extend the hip joint in phase II of the STS transfer. In contrast, when using the incorrect method of providing standing assistance, a negative external torque value was barely observed in phase I of the STS transfer when the robot patient bent its hip and knee joints; an external torque was only measured while extending the hip joint, as illustrated in Figure 11b. \begin{table}
\begin{tabular}{l c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Phase**} & \multirow{2}{*}{**Value**} & \multicolumn{6}{c}{**Correct**} & \multicolumn{6}{c}{**Incorrect**} \\  & & \multicolumn{1}{c}{_Teacher A_} & \multicolumn{1}{c}{_Teacher B_} & \multicolumn{1}{c}{_Teacher C_} & \multicolumn{1}{c}{_Teacher D_} & \multicolumn{1}{c}{_Teacher A_} & \multicolumn{1}{c}{_Teacher B_} & \multicolumn{1}{c}{_Teacher C_} & \multicolumn{1}{c}{_Teacher D_} \\ \hline  & *min. hip joint & & & & & & & & & & \\  & external torque & & -21.30 & -21.86 & -25.12 & -16.68 & -4.47 & -5.65 & -2.34 & -1.52 & 0.002 \\  & *min. knee joint & & & & & & & & & & \\  & external torque & & & & & & & & & & \\  & *min. ankle joint & & & & & & & & & & \\  & external torque & & & & & & & & & & \\  & *average hip joint & & & & & & & & & & \\  & external torque & & & & & & & & & & \\  & & & & & & & & & & & \\  & & & & & & & & & & & \\  & & & & & & & & & & & \\  & & & & & & & & & & & & \\  & & & & & & & & & & & \\ \hline  & & & &As shown in Figure 12, the external torque measured from the knee joint is similar to that measured from the hip joint. Using the correct method of standing assistance, the negative external torque value that was necessary to bend the knee joint was observed in phase I of the STS transfer. In phase II of the STS transfer, a positive external torque value necessary to extend the knee joint was observed, as shown in Figure 12a. The negative external torque value necessary to bend the knee joint was hardly observed in phase I of the STS transfer when using the incorrect method. However, the torque necessary to extend the knee joint was measured in both phases I and II of the STS transfer, as shown in Figure 12b. The external torque measured from the ankle joint is shown in Figure 13a,b. Using the correct method, the negative external torque value that was necessary to bend the ankle joint was observed in phase I of the STS transfer, and the external torque necessary to flex the ankle joint was measured in phase II of the STS transfer, as shown in Figure 13a. Using the incorrect method of standing assistance, the negative external torque value that was necessary to bend the ankle joint was not observed in phase I of the STS transfer, whereas the torque necessary to flex the knee joint was measured in phase II of the STS transfer, as shown in Figure 13b. According to the statistical analysis presented in Table 3, significant differences in the minimum external torque values required to flex the hip (\(p\) = 0.002), knee (\(p\) = 0.002), and ankle (\(p\) = 0.006) joints during phase I of the STS transfer were observed between the correct and incorrect methods of providing standing assistance. In addition, significant differences in the average external torque were observed in the hip (\(p\) = 0.023), knee (\(p\) = 0.033), and ankle (\(p\) = 0.047) joints. Furthermore, in phase II of the STS transfer, a significant difference was observed in the maximum external torque (\(p\) = 0.028) and the average external torque (\(p\) = 0.034) measured from the hip joint.