## 5 Experimental Results
### Active Suspension Control Effect
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Parameter**} & \multicolumn{4}{c}{**Control Strategy**} \\ \cline{2-5}  & **Passive** & **SMC** & **FSMC** & **HOA-FSMC** \\ \hline Body’s Acceleration (m/s\({}^{2}\)) & 4.0913 & 3.8168 & 3.6437 & 3.3777 \\ Improvement (\%) & 0 & 6.70 & 10.94 & 17.44 \\ \hline Suspension’s Deflection (m) & 0.0196 & 0.0185 & 0.0177 & 0.0170 \\ Improvement (\%) & 0 & 4.60 & 9.71 & 12.99 \\ \hline Tires’ Dynamic Load (N) & 32,315.0688 & 30,098.2087 & 28,690.1635 & 27,756.7824 \\ Improvement (\%) & 0 & 6.86 & 11.21 & 14.11 \\ \hline \hline \end{tabular}
\end{table} 
Table 12: RMS values of Class F pavement evaluation indices. strating that integrating fuzzy-logic-based control with sliding-mode control can improve the system's performance. Among all the active suspensions, the HOA-FSMC active hydropneumatic suspension achieves the best overall vehicle performance optimization. Although the FSMC and SMC active hydropneumatic suspensions have slightly lower performance improvements than HOA-FSMC, they still outperform the passive hydroropneumatic suspension, indicating that active hydropneumatic suspension systems based on sliding-mode control theory can effectively handle different road excitations and exhibit strong robustness and adaptability. From Figure 14 and Table 10, it is clear that the HOA-FSMC active hydropneumatic suspension focuses on comfort optimization on B-grade roads. Compared with the passive hydropneumatic suspension, the RMS value of the body's acceleration was reduced by 21.2%, and the RMS values of suspension's dynamic deflection and tires' dynamic load were reduced by 10.34% and 9.21%, respectively. This demonstrates that the controller significantly improved ride comfort by prioritizing body acceleration adjustments, ensuring ride comfort during the vehicle's operation. From Figure 15 and Table 11, it can be seen that on D-grade roads, the HOA-FSMC active hydropneumatic suspension's optimization plan focuses more on the vehicle's stability. Compared with the passive hydropneumatic suspension, the RMS values of the body's acceleration, tires' dynamic load, and suspension's dynamic deflection decreased by 18.86%, 12.1%, and 11.55%, respectively. This result indicates that while enhancing the vehicle's stability, the optimization plan still considers ride comfort, ensuring a balance between stability and ride comfort. From Figure 16 and Table 12, it is clear that for F-grade roads, the HOA-FSMC active hydropneumatic suspension's optimization plan takes multiple performance indicators into account, maintaining a balanced improvement among the body's acceleration, suspension's dynamic deflection, and tires' dynamic load. The optimized RMS values of the body's acceleration, the suspension's dynamic deflection, and the tires' dynamic load decreased by 17.44%, 12.99%, and 14.11%, respectively. This balanced improvement indicates that the optimization plan for F-grade roads focuses on enhancing the overall performance, ensuring both ride comfort and vehicle stability and safety. The optimized control parameters from the HOA satisfy the dynamic performance needs across varying road conditions. Specifically, the B-grade road plan focuses on ride comfort, the D-grade road plan balances stability and comfort, and the F-grade road plan achieves balanced improvement across multiple indicators.