## 4 Simulation and Result Analysis
### Crosswind Test  
The crosswind test is important because crosswind is the most common lateral force, except for obstacles on the road, in practical application scenarios [43]. The general wind scale is the wind speed at 10 m above the ground, which prevents a higher wind speed on the ground. However, many overpasses are applied to urban expressways in the construction of modern cities. Sometimes, the height of these overpasses can even reach the height of 20 m from the ground (equivalent to approximately seven floors). The crosswind at this location is very dangerous to fast vehicles with a large mass and a high mass center on rainy and snowy days. The research condition of crosswind rollover is not only the condition of single lateral external force but also has a certain reference value \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Test Results (Unit)** & **CDC-LTR** & **CDC-ODDF** & **Percentage Point 1** \\ \hline \multirow{4}{*}{Roll angle (rad)} & maximum & 0.008001 & 0.07378 & \(-\)7.79\% \\  & minimum & \(-\)0.09906 & \(-\)0.09281 & \(-\)6.30\% \\  & average & \(-\)0.04896 & \(-\)0.04605 & \(-\)5.94\% \\  & standard deviation & 0.03012 & 0.02856 & \(-\)5.18\% \\ \hline \multirow{4}{*}{Roll angle rate (rad/s)} & maximum & 0.5657 & 0.4664 & \(-\)5.34\% \\  & minimum & \(-\)0.8282 & \(-\)0.7776 & \(-\)6.11\% \\ \cline{1-1}  & average & \(-\)0.02054 & \(-\)0.01906 & \(-\)7.21\% \\ \cline{1-1}  & standard deviation & 0.09313 & 0.08186 & \(-\)12.1\% \\ \hline \hline \end{tabular}  
* Percentage point = ((CDC-ODDF) \(-\) (CDC-LTR))/(CDC-LTR) \(\times\) 100%.  
\end{table} 
Table 4: Main comparison results of fishhook test (CDC-LTR, CDC-ODDF). in practical application. The basic parameters of the crosswind test simulation analysis are shown in Table 5.  
Crosswind conditions are more severe because the friction coefficient of the crosswind section is small. Thus, serious instability sideslip occurs before a rollover. Therefore, these factors are combined with the test results for a brief analysis. The results of crosswind test simulation are shown in Figure 9.  
According to the results of the roll angle rate and LTR, the vehicle suffers from the first low-friction crosswind section from the 0.8 th second to the 2 nd second, enters the second friction crosswind section from the 3.5 th second to the 4.2 th second, and the vehicles start to lose stability from the 5.2 th second to the 5.5 th second (the condition is mainly sideslip; some wheels are off the ground, but no rollover occurs). The serious sideslip occurs after the 7.2 th second, and the vehicles can no longer maintain normal driving. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Test Parameters** & **Value** & **Unit** \\ \hline Longitude target speed & 80 & km/h \\ Friction coefficient (no crosswind) & 0.85 & - \\ Friction coefficient (crosswind) & 0.2 & - \\ Wind speed & 8 & m/s \\ Simulation time & 8 & second \\ Road condition & straight & - \\ [Threshold of CDC-LTR control] & 0.9 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Main parameters of crosswind test. Figure 9: Cont. The LTR of a passive suspension vehicle experiences a jump from \(+1\) to \(-1\) at approximately the 5.2 th second, which means that the vehicle has a \"jump\" on all wheels. Although no rollover occurs, the vehicle completely loses control. The vehicle with CDC is also unstable. Nevertheless, not all the wheels come off the ground. Notably, a vehicle with CDC-ODDF never reaches the rollover limit ([LTR] \(<1\) from start to the end). Moreover, the comparison of CDC-LTR and CDC-ODDF in two crosswind regions with low friction and the first instability region is analyzed on the basis of vertical and damping forces in Figure 10.  
In the first crosswind section (from the 0.8 th second to the 2 nd second), the change of damping forces on the left side with the two CDC control strategies is basically the same, while the damping forces on the right side is evidently compensated for the left side with CDC-ODDF.