## 4 Experimental Verification  
In order to further verify the validity of the improved model, an electromagnetic track launcher experimental platform is built for this research, whose working principle is as follows: the pulsed power supply is charged by a battery charger, which generates an excitation current and causes the armature to launch.  
The light curtain device is used to measure the armature velocity in this paper, the schematic diagram of the device is shown in Figure 18.  
When the armature passes through the light curtain at a high speed, two light curtains record the armature passing time; the distance of the light curtain handle is fixed at 550 mm, and the armature velocity can be calculated by reading the time difference between the armature passing through the two light curtain.  
An XGK-2002 type light curtain is used in this experiment, which has the advantages of high sensitivity, not being affected by ambient light and it can test high-speed objects, etc. Its technical indicators are shown in Table 6.  
Figure 18: Schematic diagram of the light curtain device.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Number**} & \multicolumn{2}{c}{**Finite Element**} & \multicolumn{2}{c}{**Predicted Values of**} \\  & **Calculated Values** & **Improved Model** & **Relative Error** \\  & **(\(L_{e}\))/(\(\mu\)H/m)** & **(\(L_{p}\))/(\(\mu\)H/m)** & **(\(e_{rL}\))/(\%)** \\ \hline
1 & 0.9951 & 0.9867 & 0.84 \\
2 & 1.0010 & 1.0137 & 1.27 \\
3 & 1.0247 & 1.0050 & 1.92 \\
4 & 1.0454 & 1.0546 & 0.87 \\
5 & 1.1799 & 1.1708 & 0.77 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Relative error analysis of the inductance gradient.  
Where the sensor module is mainly used to collect experimental data, the power module and battery charger provide an excitation current for the armature, the light curtain is used to measure the armature velocity and the sandbox is used to receive the armature.  
The armature velocity under actual conditions is obtained by the experimental platform, and compared with the calculated value by Ls-dyna and the predicted value of the improved model, the relative error can be calculated according to Equation (34).  
\[\left\{\begin{array}{l}e_{\mathrm{rs}}=\left|\frac{v_{\mathrm{e}}-v_{ \mathrm{s}}}{v_{\mathrm{e}}}\right|\\ e_{\mathrm{rm}}=\left|\frac{v_{\mathrm{e}}-v_{\mathrm{s}}}{v_{\mathrm{e}}} \right|\end{array}\right. \tag{34}\]  
where \(v_{\mathrm{e}}\) is the experimental test value, \(v_{\mathrm{s}}\) the calculated values by Ls-dyna and \(v_{m}\) the predicted values of the improve model. \(e_{\mathrm{rs}}\) is the relative error between \(v_{\mathrm{e}}\) and \(v_{\mathrm{s}}\), and \(e_{\mathrm{rm}}\) the relative error between \(v_{\mathrm{e}}\) and \(v_{\mathrm{m}}\).  
The relative errors are calculated as shown in Table 7.  
It can be seen that \(e_{\mathrm{rm}}\) is reduced by 4.61% compared with \(e_{\mathrm{rs}}\), which is closer to the actual launch situation, further proving the validity of the improved model. In conclusion, it can be considered that the improved model in this paper can predict the output under the actual working process more accurately, which provides a certain theoretical basis for the full true simulation of electromagnetic track launch.