# Research on Inertial Force Attenuation Structure and Semi-Active Control of Regenerative Suspension
## 5 The Verification of HVRS Suspension Characteristics
### Random Road Comparison Test of Two Suspension Configurations  
The parameters of the two suspension configurations in the bench comparison test are shown in Table 5. The road excitation for the suspension test is to use a standard C-class road surface at a speed of 60 km/h. The time-domain data curves of the sprung mass acceleration \(\sigma_{zz}\), relative dynamic load \(\sigma_{EI}/G_{i^{\prime}}\), and dynamic deflection \(\sigma_{sd}\) of two suspension configurations were obtained through experiments, as shown in Figure 14. The comparison of root mean square values of suspension characteristic data is shown in Table 6. \begin{table}
\begin{tabular}{l l l l} \hline \hline
**Status** & \(\sigma_{zz}\)**/m/s\({}^{2}\)** & \(\sigma_{FE}\)\(G_{i}\) & \(\sigma_{sd}\)**/m** \\ \hline Without HVRS & 2.7963 & 0.3791 & 0.0161 \\ With HVRS & 1.8912 & 0.1936 & 0.0156 \\ Changed & \(-32.37\%\) & \(-48.93\%\) & \(-3.11\%\) \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Comparison of suspension test results. Figure 14: (a) Comparison of sprung mass acceleration; (b) comparison of relative dynamic loads; (c) comparison of dynamic deflection. \begin{table}
\begin{tabular}{l l l l} \hline \hline
**Parameter** & **Symbol** & **Value** & **Unit** \\ \hline Sprung mass & \(m_{s}\) & 312.5 & kg \\ Unsprung mass & \(m_{u}\) & 43.5 & kg \\ Equivalent inertial mass & \(m_{r}\) & 58.8 & kg \\ Suspension spring stiffness & \(k_{s}\) & 20,000 & N/m \\ Wheel stiffness & \(k_{u}\) & 180,000 & N/m \\ Dissipation resistance & \(R_{d}\) & 60 & \(\Omega\) \\ Suspension HVRS stiffness & \(k_{h}\) & 30,000 & N/m \\ Suspension HVRS damping coefficient & \(c_{h}\) & 268 & N-s/m \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Parameters of suspension. Analyzing Figure 14 and Table 6, it can be seen that the suspension characteristics of the two configurations are essentially the same in terms of dynamic deflection in the time domain. The root mean square value of dynamic deflection of HVRS suspension is 3.11% lower than that of suspension without an HVRS. the root mean square value of the sprung mass acceleration of HVRS suspension is 32.37% lower than that of suspension without an HVRS; the root mean square value of the relative dynamic load of HVRS suspension is 48.93% lower than that of suspension without an HVRS. Therefore, the HVRS is very effective in improving the performance of energy regenerative suspension. To further analyze the reasons for the effectiveness of the HVRS from the frequency domain characteristics, the spectral density comparison of the suspension sprung mass acceleration, relative dynamic load, and dynamic deflection obtained through spectral analysis of experimental data is shown in Figure 15.  
From Figure 15a, it can be seen that when the excitation frequency is lower than the frequency \(f_{msy}\), the sprung mass acceleration of the HVRS suspension slightly increases compared to the original configuration suspension in the first main frequency range. When the excitation frequency is higher than the frequency \(f_{msy}\) but lower than the frequency \(f_{muy}\), the sprung mass acceleration of HVRS suspension is significantly reduced compared to the original configuration suspension. When the excitation frequency is higher than the frequency \(f_{muy}\) but lower than the frequency \(f_{muy}\), the sprung mass acceleration of the original configuration suspension. When the excitation frequency is higher than the frequency \(f_{muy}\) but lower than the frequency \(f_{muy}\), the sprung mass acceleration of the excitation frequency is higher than the frequency \(f_{muy}\), the sprung mass acceleration of HVRS suspension is significantly reduced compared to the original configuration suspension. It can be seen that HVRS suspension can solve the problem of deteriorating sprung mass acceleration caused by equivalent inertial mass.