5.3.2. Calibration Results for RFCP-B

The relationship between the angle of repose formed by mixing the soybean seed particles with the organic glass spheres and rolling friction coefficient between the soybean seed particles and boundary (organic glass spheres) is shown in Figure 16.

**Figure 16.** The relationship between the angle of repose and the RFCP-B for (**a**) SN42, (**b**) JD17, and (**c**) ZD39.

For the three varieties, the angle of repose tended to increase as the RFCP-B increased. The repose angle results for the three varieties (SN42, 18.72◦; JD17, 26.16◦; and ZD39, 28.56◦.) were obtained by measuring the repose angle test of the soybean–glass ball mixture. Taking SN42 as an example, the relationship between the angle of repose and RFCP-B was obtained by liner fitting, and the formula is shown as follows.

$$\mathbf{y} = 188.29\mathbf{x} + 17.344\ (\mathbf{R}^2 = 0.987\mathbf{\hat{9}}) \tag{9}$$

The result (18.72◦) of the repose angle test for SN42 was entered into the Formula 9, and the RFCP-B was calculated to be 0.008. The same method was used to calculate the RFCP-B, which was 0.037 and 0.028 for JD17 and ZD39, respectively.

#### **6. Test Verification of Calibration Parameters**

The accuracy of the calibration parameters was verified by rotating cylinder test and self-flow screening test. At the same time, the difference between the test results and simulation results when the rolling friction coefficient was ignored was also analyzed.
