# Design and Test of Real-Time Detection System for Cleaning Loss of Rapeseed Harvester
## 3 Test and Discussion
### Field Experiment and Test  
On May 25, 2024, a field experiment and test were carried out in Gaoyou City, Yangzhou. The loss sensor was installed at a height of 0.2 m below the tail of the cleaning screen at a 45\({}^{\circ}\) angle to the ground. The test machine was a 4 LZY-5.0Z rapeseed combine, produced by Xingguang Agricultural Machinery Co., Ltd., located at No. 1699 Xingguang Street, Hefu Town, Huzhou City, Zhejiang Province, as shown in Figure 14. The rapeseed variety \"Ningza 182\" was harvested in the experiment; the moisture content of the kernel was 12.8%, and the 1000 grain weight was 4.1 g.  
The cleaning loss sensor module in the designed loss detection system can only detect the lost kernels impacting on the inductive plate and cannot receive all the lost kernels thrown from the tail of the cleaning screen. Therefore, it was necessary to obtain the proportional coefficient of the loss detection system through a pre-experiment before the field experiment. During the pre-experiment, the harvested rapeseed material was fed to the cutting table of the rapeseed harvester to obtain the actual number of lost kernels, \(Q_{L}\) \begin{table}
\begin{tabular}{c c c} \hline
**Calibration** & **Average** & **Monitoring** \\
**Material** & **Number (Grains)** & **Accuracy (\%)** \\ \hline Kernel (50 grains) & 49.0 & 98.0 \\ Kernel (100 grains) & 97.8 & 97.8 \\ Kernel (150 grains) & 141.8 & 94.5 \\ Kernel (200 grains) & 183.2 & 91.6 \\ Caro shell (10 g) & 5 & – \\ Short stem (10 g) & 0 & – \\ Kernel (100 grains) + carob shell (10 g) & 96.8 & 96.8 \\ Kernel (100 grains) + short stem (10 g) & 95.2 & 95.2 \\ Kernel (100 grains) + carob shell (5 g) + short stem (5 g) & 96.2 & 95.5 \\ \hline \end{tabular}
\end{table} 
Table 4: Material calibration test results. and the detected number of lost kernels, \(Q_{m}\). The formula for calculating the proportional coefficient of the loss detection system is as follows:  
\[k=\frac{Q_{L}}{Q_{m}} \tag{6}\]  
During the pre-experiment, the proportional coefficient of the loss detection system was determined to be 3.2 through three repeated feeding tests, as shown in Table 5.  
In order to verify the effect of the designed system in the field, the field experiment and test were carried out. The harvester used the manual feeding method to remove the cleaning materials from the harvested rapeseed. Under the condition that the feeding amount was the same each time, the proportional coefficient of the loss detection system was set as 3.2, and the speed of the three-speed fan was set as 700, 900 and 1200 r/min, respectively. The actual number of lost kernels after cleaning and the detected number of lost kernels obtained in the system test after operation at the speed of the three-speed fan were counted, as shown in Table 6. The detection accuracy of the final loss detection system reached more than 95%, indicating that the loss detection system is able to recognize the signals of the lost kernels well and has the ability to operate and detect them under complex harvesting conditions. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Fan Speed** & \begin{tabular}{c} **Number of Lost Kernels** \\ **Shown by Detection System** \\ **(Grains)** \\ \end{tabular} & \begin{tabular}{c} **Actual Number of** \\ **Kernels Lost in** \\ **Cleaning (Grains)** \\ \end{tabular} & \
\begin{tabular}{c} **System’s Detection** \\ **Accuracy (\%)** \\ \end{tabular} &
\begin{tabular}{c} **Error Compared to** \\ **Manual Detection** \\ \end{tabular} \\ \hline
700 & 3426 & 3638 & 95 & 5\% \\
900 & 4578 & 4804 & 95.3 & 4.7\% \\
1200 & 5796 & 6025 & 96.2 & 3.8\% \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Detection accuracy of loss detection system under different fan speeds. Figure 14: Field experiment and test: (**a**) field test site: 1. Starlight 4 LZY-5.0Z rapeseed combine, 2. cleaning and discharging port, 3. loss detection device; (**b**) display of loss detection system: 4. serial display. (The non-English words in (**a**) refer to the manufacturer of the harvester used in the test).