4.2.2. Test Design

Herein, the influences of the forward speed, the rate of rotation of the blowers at the feed port of the collection devices, and the rate of rotation of the drum on the harvesting effect of the harvester were discussed. To this end, taking the forward speed, wind velocity of blowers, and rate of rotation of the drum as test factors, quadratic regression orthogonal rotating combination tests were conducted. Combined with the pre-test data and material characteristics of dandelion seeds, the test ranges of the forward speed, wind velocity at blower inlets, and rate of rotation of the drum were set to 0.8~1.2 m·s<sup>−</sup>1, 1.0~2.0 m·s<sup>−</sup>1, and 300~500 rpm [35], respectively. The test factors are numbered (Table 3) and the simulation test schemes and results are listed in Table 4.


**Table 3.** Coding of simulation test factors.


**Table 4.** Experiment scheme and results.

#### *4.3. Test Analysis*

Software Design-Expert 8.0 was adopted to perform variance analysis of data in Table 4 and results are listed in Table 5 [36]. It can be seen from Table 5 that the test model is extremely significant (*p* < 0.0001), suggesting that the designed tests are reasonable and effective; the coefficient of determination *R*<sup>2</sup> is 0.9626, indicative of a high degree of fitting of the regression equation. The forward speed, wind velocity of blowers, and rate of rotation of the drum all significantly affect the collection rate (*p* < 0.05). The interaction term between the forward speed and wind velocity of blowers exerts significant influence on the collection rate; the interaction term between the rate of rotation of the blowers and drum also has a significant influence. The response surfaces of the influence of the interaction terms of the test factors on the collection rate are illustrated in Figures 20 and 21. Through a multiple regression of the test results, the regression equation of the collection rate can be obtained as follows:

$$\varphi = +87.16 - 0.24\mathbf{A} + 2.16\mathbf{B} + 2.32\mathbf{C} + 1.32\mathbf{A}\mathbf{B} - 0.35\mathbf{A}\mathbf{C} + 1.60\mathbf{B}\mathbf{C} + 0.083A^2 - 2.22B^2 - 8.24\mathbf{C}^2 \tag{9}$$

**Figure 20.** Interaction between forward speed and wind velocity of blowers.


**Table 5.** Analysis of variance of regression equations.

**Figure 21.** Interaction between wind velocity of blowers and drum rotational speed.
