# Design and Experiment of Grain Litter for Sorghum Harvester
## 4 Field Experiment and Analysis
### Orthogonal Test Results and Analysis
#### 4.4.3 Response Surface Analysis  
In order to further study the interaction relationship between each test factor and the test index, the response surface method was used to analyze the impact of the interaction on the loss rate of ear shedding and the loss rate of missed harvest, that is, one factor was fixed at the level of 0, and the influence law of the other two factors on the test index was investigated. As shown in Figure 5a, when the rotation speed of the grain lifter is 330 r/min, the loss rate of ear shedding increases with the increase in the forward speed. This is because, with the increase in the forward speed of the harvester, the difficulty of separating the inner and outer plants by the harvester increases, resulting in the increase in ear shedding loss. With the increase in the tilt angle of the grain lifter, the supporting effect of the front on the lodging plant was enhanced, and the position of the posterior row became higher, which reduced the loss of ear. However, with the increase in the tilting angle, the sliding resistance of the stalk along the surface of the filler increased, which reduced the supporting effect of the filler on the fallen plants and led to the increase in the loss rate of ears. As shown in Figure 5b, when the tilt angle of the grain lifter is present, the rate of ear loss decreases first and then increases with the increase in the rotation speed of the grain lifter. This is because with the increase in the rotation speed of the grain lifter, the front part of the grain lifter strengthened the effect of helping and dividing the grass of the fallen plants, and the backward conveying speed of the stalks and the backward conveying speed \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & \multicolumn{4}{c}{**Loss Rate of Ear**} & \multicolumn{4}{c}{**Loss Rate of Missing Collection**} \\ \cline{2-10}
**Sources** & **Sum of Squares** & **Degree of Freedom** & **Mean Square** & **F Value** & **\(p\) Value** & **Sum of Squares** & **Degree of Freedom** & **Mean Square** & **F Value** & **\(p\) Value** \\ \hline \(X_{1}^{2}\) & 0.00716 & 1 & 0.00716 & 0.28 & 0.6118 & 0.047 & 1 & 0.047 & 0.47 & 0.5172 \\ \(X_{2}^{2}\) & 3.61 & 1 & 3.61 & 142.24 & \(<\)0.0001 ** & 3.01 & 1 & 3.01 & 30 & 0.0009 ** \\ \(X_{3}^{2}\) & 0.77 & 1 & 0.77 & 30.48 & 0.0009 ** & 1.3 & 1 & 1.3 & 12.94 & 0.0088 ** \\ \hline Residual & 0.18 & 7 & 0.025 & & & 0.7 & 7 & 0.1 & & \\ Lack of fit & 0.047 & 3 & 0.016 & 0.48 & 0.7111 & 0.4 & 3 & 0.13 & 1.72 & 0.2998 \\ Pure error & 0.13 & 4 & 0.033 & & 0.31 & 4 & 0.077 & & & \\ Correct total & 14.5 & 16 & & & 19.63 & 16 & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: _Cont._of the stalks at the dead corner of the barrier net increased, reducing the loss of ears. With the increase in the rotation speed of the grain lifter, the lifting speed of the lodging plant was too fast, resulting in the increase in the broken rod of the plant and the increase in the number of plants outside the ear discharge opening, resulting in the poor ear discharge, resulting in the increase in ear loss rate. The loss rate of ear shedding increased with the increase in forward speed, and the reasons were similar to the analysis in Figure 5a. As shown in Figure 5c, when the forward speed was 1.0 m/s, the spike loss rate first decreased and then increased with the increase in the rotation speed of the crop helper, for reasons similar to those analyzed in Figure 5b. With the increase in the tilt angle of the crop support, the loss rate of ear removal first decreased and then increased, and the reasons were similar to the analysis in Figure 5a. As shown in Figure 6a, when the rotation speed of the grain lifter is 330 r/min, the leakage loss rate increases with the increase in the forward speed. The reason is that with the increase in the forward speed of the harvester, the ability of the grain lifter to lift the fallen and crooked plants cannot meet the actual needs of production, resulting in a continuous increase in the leakage loss rate.