## 5 Results and Discussion
It can be seen that the adaptive hybrid control exhibits better performance than the passive damper. It produces higher total energy absorber efficiency, smaller maximum damping force, and also smaller maximum stroke. To achieve that result, there requires an accurate model of the landing gear system. This indicates that there is no significant difference between the estimated damping force and the real one. Additionally, the aircraft mass should also be estimated accurately before aircraft touchdown. Thus, the controller may not be useful if the model is unable to closely follow the real dynamics of an MR damper. Table 6 describes the performance of the landing gear using GA-NN and PGE-NN in different landing conditions. It can be seen that GA-NN and PGE-NN exhibit similar levels of performance. \begin{table}
\begin{tabular}{c c c c} \hline  & **Maximum of Stroke** & **Maximum of Damping** & **Total Energy Absorber** \\  & \(\mathbf{s_{\max}}\) **(m)** & **Force \(\mathbf{F_{\max}}\) (kN)** & **Efficiency \(\mathbf{\eta}\) (\%)** \\ \hline Passive Damper & 0.221 & 24.2 & 80.4 \\ Adaptive Hybrid Control & 0.210 & 21.8 & 94.0 \\ GA-NN & 0.197 & 22.9 & 94.6 \\ PGE-NN & 0.194 & 22.8 & 94.9 \\ \hline \end{tabular}
\end{table} 
Table 4: Efficiency of the landing gear using the passive damper, adaptive hybrid control, GA-NN, and PGE-NN in the case of \(m_{1}=680\) kg and \(v=3\) m/s. \begin{table}
\begin{tabular}{c c c c c c c} \hline  & \multicolumn{3}{c}{**Passive Damper**} & \multicolumn{3}{c}{**Adaptive Hybrid Control**} \\ \hline  & \(\mathbf{F_{\max}}\) **(kN)** & \(\mathbf{s_{\max}}\) **(m)** & \(\mathbf{\eta}\) **(\%)** & \(\mathbf{F_{\max}}\) **(kN)** & \(\mathbf{s_{\max}}\) **(m)** & \(\mathbf{\eta}\) **(\%)** \\ \hline \(m_{1}=560\) kg & & & & & & \\ \hline \(v=2\) m/s & 14.3 & 0.177 & 79.4 & 14.3 & 0.146 & 96.5 \\ \(v=2.5\) m/s & 16.9 & 0.193 & 81.1 & 16.9 & 0.164 & 95.8 \\ \(v=3\) m/s & 19.7 & 0.207 & 84.9 & 19.7 & 0.186 & 94.6 \\ \hline \(m_{1}=600\) kg & & & & & & \\ \hline \(v=2\) m/s & 14.5 & 0.186 & 80.9 & 15.3 & 0.146 & 95.3 \\ \(v=2.5\) m/s & 17.2 & 0.200 & 83.3 & 18.2 & 0.160 & 98.8 \\ \(v=3\) m/s & 20.0 & 0.212 & 87.9 & 21.2 & 0.181 & 97.4 \\ \hline \(m_{1}=640\) kg & & & & & & \\ \hline \(v=2\) m/s & 14.7 & 0.194 & 82.7 & 15.6 & 0.157 & 96.4 \\ \(v=2.5\) m/s & 17.5 & 0.207 & 85.9 & 18.5 & 0.174 & 96.4 \\ \(v=3\) m/s & 21.5 & 0.217 & 86.1 & 21.5 & 0.195 & 95.8 \\ \hline \(m_{1}=680\) kg & & & & & & \\ \hline \(v=2\) m/s & 14.9 & 0.201 & 84.9 & 15.8 & 0.168 & 95.9 \\ \(v=2.5\) m/s & 18.6 & 0.212 & 84.7 & 18.8 & 0.189 & 94.1 \\ \(v=3\) m/s & 24.2 & 0.221 & 80.4 & 21.8 & 0.210 & 94.0 \\ \hline \(m_{1}=575\) kg (Random Case 1) & & & & & \\ \hline \(v=2.25\) m/s & 15.7 & 0.188 & 80.6 & 15.7 & 0.158 & 96.0 \\ \hline \(m_{2}=625\) kg (Random Case 2) & & & & & \\ \hline \(v=2.75\) m/s & 18.9 & 0.210 & 87.3 & 19.9 & 0.178 & 96.9 \\ \hline \(m_{3}=654\) kg (Random Case 3) & & & & & \\ \hline \(v=2.35\) m/s & 16.8 & 0.205 & 85.7 & 17.7 & 0.173 & 96.0 \\ \hline \end{tabular}
\end{table} 
Table 5: Damper performance using the passive damping and adaptive hybrid control in differing landing cases. In the twelve trained landing cases, the total energy absorber efficiency is very high, ranging from 94% to 97%. In particular, it should be noted that the proposed controller does not need the online estimation of landing conditions. In order to verify the generalization ability of the proposed controller, simulations in the three random landing cases are executed, which are out of data training. It can be seen that the proposed controller also exhibits comparable performance in the random cases. This indicates that the proposed controller is not overfitted. Compared to the adaptive hybrid controller, the proposed controller produces a slightly higher maximum damping force; however, it achieves a marginally smaller maximum stroke. Thus, there is a small difference in total energy absorber efficiency between the proposed controller and the adaptive hybrid controller.