## 3 Analysis of Results
### Discrete Element Simulation Analysis
#### 3.1.3 Orthogonal Test Analysis  
In this paper, the interaction between the level of each factor and the system in the excavation shovel is investigated by the orthogonal test method [31; 32; 33; 34]. The three factors that have the greatest influence on the working resistance of the shovel and the overall energy consumption of the Fritilariae ussuriensis maxim harvester are the shovel surface inclination, digging speed, and digging depth in the Fritilariae ussuriensis maxim harvesting and excavation operation. In order to investigate the specific influence of the above three factors on the digging resistance of the shovel blade and soil compression force, and to provide some research objectives and basis for kinematic simulation analysis, a three-factor and three-level orthogonal test is designed. This orthogonal test is performed by using L\({}_{9}\)(3\({}^{4}\)) orthogonal table, and the experimental data are processed by polar difference analysis and the best combination of parameters is selected. Based on the agronomic characteristics and harvesting techniques of Fritilariae ussuriensis maxim, the excavation depth of this experiment is set at 100-140 mm. The rated working speed of the Fritilariae ussuriensis maxim harvester ranges from 0.25 to 0.55 m/s, so the operating speed is 0.3 m/s, 0.4 m/s, and 0.5 m/s. Excavation shovel face inclination and digging resistance are closely related, the shovel face inclination becomes larger, the  
Figure 15: Model reliability analysis validation curve. soil breaking performance becomes better, but the digging resistance will also increase; the shovel face inclination becomes smaller, the digging resistance becomes smaller, but the soil breaking performance will also be weakened. When the shovel inclination angle is too large or too small, it will affect the whole machine efficiency of the Fritilariae ussuriensis maxim harvester. Therefore, the shovel inclination angle is selected within the range of values of 20\({}^{\circ}\), 25\({}^{\circ}\), and 30\({}^{\circ}\) for the test. The factor levels of the orthogonal test are displayed in Table 6.  
This test is designed with reference to the L9(3\({}^{4}\)) orthogonal test table, and a total of nine groups of simulation tests are conducted. The changes in digging resistance of the corresponding groups is derived separately, and the mean value of the parameters in the table within the stable phase is taken as the response value. The specific experimental design is shown in Table 7.  
By analyzing the nine sets of data in Table 7, the range analysis details of the orthogonal experiment can be obtained, as shown in Table 8. From Table 8, it can be seen that the digging resistance \(F\) and three factors are positively correlated, where the shovel face inclination \(B\) has the most significant effect on the value of digging resistance, followed by the digging depth, and the operating speed. However, when choosing the optimal combination of parameters during the operation, it is not only necessary to consider excavation resistance \(F\), but also to consider the specific force situation of the agglomerate during the operation process, the planting and harvesting process requirements of Fritilariae ussuriensis maxim, and the specific operating environment for setting. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Level**} & **Operating Speed _A_** & **Shovel Surface** & **Digging Depth _C_** \\  & **(m/s)** & **Inclination \(B\) (\({}^{\circ}\)) & **(mm)** \\ \hline
1 & 0.3 & 20 & 100 \\
2 & 0.4 & 25 & 120 \\
3 & 0.5 & 30 & 140 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Orthogonal test factor level table.