*3.4. Optimization Model Analysis and Laboratory Test Validation*

Based on the aforementioned results of the regression model of the test indicators and the conditions of picking operation of the potato picking device, the constraints of each test factor were set in the Design Expert12 software, with the objective function shown in Equation (14). The optimum combination of parameters was found to be 19.57 r/min for the spring-finger speed, 0.61 m/s for the forward speed and 71.31 mm for the embedded depth, with corresponding loss rates of 1.18% and 5.71% for the wounded potato rate.

$$\begin{cases} \min Y\_1 = f\_1(A, B, \mathcal{C}) \\ \min Y\_2 = f\_2(A, B, \mathcal{C}) \\ \quad \quad Y\_1 \le 5\% \\ \quad \quad Y\_2 \le 6\% \\ \text{5 } \text{r/min} \le A \le 45 \text{ r/min} \\ \quad 0.2 \text{ m/s} \le B \le 1.6 \text{ m/s} \\ \quad 50 \text{ mm} \le \mathcal{C} \le 100 \text{ mm} \end{cases} \tag{14}$$

To verify the reliability of the model prediction results, the optimised parameters were rounded and then subjected to a validation test, setting the spring-finger speed at 20 r/min, the forward speed at 0.6 m/s and the embedded depth at 70 mm. The test was carried out three times and the results were averaged, resulting in a loss rate of 1.48% and a wounded potato rate of 4.98%. The test verification results are in general agreement with the optimised analysis and can be used as the optimum working parameters for this picking mechanism.
