## 4 Analysis of Electromagnetic Weft Insertion Characteristics
### Simulation Analysis  
In order to study the electromagnetic driving force generated by the extra-large width electromagnetic weft insertion drive coil and the weft insertion rate of the weft gripper during the weft insertion process, the effects of air resistance and temperature rise are ignored, and Maxwell software is used to simulate and analyze the segmented combined continuous acceleration device. The simulation parameter settings are shown in Table 1:  
Figure 9a,b show the simulation model and grid division of the segmented combined 45 mm coil, respectively. It can be seen from the figure that the grid division of the weft clamp, the transmitting coil, and the moving area is relatively dense to ensure simulation calculation accuracy. \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Numerical Value** \\ \hline Current \(I\)/A & 15 \\ \hline Yoke thickness c/mm & 1 \\ \hline Coil turns \(N\) & 900 \\ \hline Coil length \(L\)/mm & 45 \\ \hline Coil inner diameter \(R_{1}\)/mm & 18 \\ \hline Coil outer diameter \(R_{2}\)/mm & 60 \\ \hline Sectional width of weft clamp a/mm & 14 \\ \hline Height of weft gripper section b/mm & 7 \\ \hline \end{tabular}
\end{table} 
Table 1: Simulation calculation parameters. Figure 9: Electromagnetic field simulation of segmented combined 45 mm coil. Figure 10 shows the change curve of the electromagnetic force in the steady state field (a) and transient field (b) of the werft clamp in the 45 mm segmented combined acceleration coil. In the steady state field, from level 1 to level 9, the electromagnetic force exerted by the werft gripper presents a pulsating trend with the coil length of 45 mm as the period. The electromagnetic force is maintained between 700 and 1400 N, and the average force is about 1000 N during the entire continuous segmented acceleration. Compared with the steady state field, under the transient setting, the overall trend of the electromagnetic force variation curve with time is consistent with the former, and the variation range is still 700-1400 N, but it does not show a periodic change law like the steady state field (a). The acceleration time of the combined coils from level 1 to level 9 decreases step by step. This is because under the acceleration of the segmented combined continuous accelerating coils, the werft gripper will fly faster and faster, and the length of the segmented combined coils of each stage will be the same, and the time spent in the flight process will be less and less. The flying speed of each level of werft gripper is shown in Figure 11. The speed as a whole presents a gradual increase trend, and the slope of the speed curve changes less, that is, the acceleration and electromagnetic force received are stable. The simulation speed of each level is shown in Table 2, and the increment ratio is consistent with the theoretical speed analysis. Table 2 shows the comparison between the minimum speed requirement of each level of 9-level coil acceleration theory and the speed obtained by the simulation of the segmented combined 45 mm coil. The results show that the segmented combined continuous acceleration coil meets the design requirements of electromagnetic werft insertion. The combined coil length is further optimized and improved on the basis of 45 mm. The steady state and transient forces of the werft clamp in the combined coil when the simulation parameters of the coil length are 30 mm and 15 mm are shown in Figures 12 and 13, respectively. Compared with Figure 10, it can be seen that the steady state field electromagnetic force of the 30 mm and 15 mm combined coils also exhibits periodic changes. In the transient field, the speed becomes faster and faster at the same acceleration distance, and the curve width becomes narrower and narrower, that is, the time spent in each level of acceleration becomes shorter and shorter.