## 6 Conclusions  
This study investigated the full-vehicle handling performance of a commercial vehicle fitted with an SLA strut front suspension system and a multi-link rear suspension system. Based on a detailed inspection of the hardpoint positions of the suspension system and steering system, a full-vehicle ADAM analysis model was constructed and used to evaluate the handling performance of the vehicle in simulated constant radius cornering tests and impulse steering tests, respectively. The corresponding steady-state and transient-state responses of the vehicle were confirmed by experimental tests. The validated model was then used to investigate the design parameters which dominated the understeer behavior of the vehicle and the effects of the three main design variables (namely, the cornering stiffness, the toe-in angle, and the camber angle) on the steady-state and transient-state vehicle handling performance. In general, the results showed that the suspension system factors affecting the understeer performance (\(K_{us}\)) can be ranked in terms of decreasing effect as follows: cornering stiffness \(>\)lateral force compliance steer \(>\)roll steer \(>\)roll camber \(>\)aligning torque. Moreover, the cornering handling performance can be improved by increasing the cornering stiffness and initial toe-in angle and reducing the initial camber angle.  
[PERSON] and [PERSON] conceived of the presented idea. We developed the theory and [PERSON] performed the CAE. [PERSON] verified the analytical methods and supervised the findings of this work. All authors discussed the results and contributed to the final manuscript.  
The authors gratefully acknowledge the financial support provided to this study by the Ministry of Science and Technology, R.O.C.  
The authors declare no conflict of interest.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Item** & **Design Variable** & \
\begin{tabular}{c} **Yaw Rate Gain** \\ **(Steady State)** \\ \end{tabular} &
\begin{tabular}{c} **Percentage** \\ **(Steady State)** \\ \end{tabular} \\ \hline Type 1 (original) & Cornering stiffness (original value) & 2.68 & 0\% \\ Type 2 & Cornering stiffness (increased by 30\%) & 3.22 & 20\% \\ Type 3 & Cornering stiffness (decreased by 30\%) & 2.21 & \(-\)17\% \\ Type 4 & Initial toe-in angle (\(-\)1\({}^{\circ}\)) & 2.35 & \(-\)12.3\% \\ Type 5 (original) & Initial toe-in angle (0\({}^{\circ}\)) & 2.68 & 0\% \\ Type 6 & Initial toe-in angle (1\({}^{\circ}\)) & 3.07 & 9.7\% \\ Type 7 & Initial camber angle (\(-\)1\({}^{\circ}\)) & 2.72 & 1.47\% \\ Type 8 (original) & Initial camber angle (0\({}^{\circ}\)) & 2.68 & 0\% \\ Type 9 & Initial camber angle (1\({}^{\circ}\)) & 2.65 & \(-\)1.11\% \\ \hline \hline \end{tabular}
\end{table}
Table 16: Effects of changes in steady-state design variables on vehicle handling performance.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Item** & **Design Variable** & \
\begin{tabular}{c} **Yaw Rate Gain** \\ **(Transient)** \\ \end{tabular} &
\begin{tabular}{c} **Percentage** \\ **(Transient)** \\ \end{tabular} \\ \hline Type 1 (original) & Cornering stiffness (original value) & 0.18099 & 0\% \\ Type 2 & Cornering stiffness (increased by 30\%) & 0.19171 & 5.92\% \\ Type 3 & Cornering stiffness (decreased by 30\%) & 0.14356 & \(-\)20.7\% \\ Type 4 & Initial toe-in angle (\(-\)1\({}^{\circ}\)) & 0.15898 & \(-\)12.2\% \\ Type 5 (original) & Initial toe-in angle (0\({}^{\circ}\)) & 0.18099 & 0\% \\ Type 6 & Initial toe-in angle (1\({}^{\circ}\)) & 0.1871 & 3.38\% \\ Type 7 & Initial camber angle (\(-\)1\({}^{\circ}\)) & 0.18309 & 1.16\% \\ Type 8 (original) & Initial camber angle (0\({}^{\circ}\)) & 0.18099 & 0\% \\ Type 9 & Initial camber angle (1\({}^{\circ}\)) & 0.17871 & \(-\)1.26\% \\ \hline \hline \end{tabular}
\end{table}
Table 17: Effects of changes in transient-state design variables on vehicle handling performance.