*2.4. Potato Trajectory Simulation Analysis*

2.4.1. Simulation Model Building in EDEM

(1) Potato simulation modelling

In this study, the physical parameters of the 'purple-flowered white' potato were tested and analysed at harvest time. The results are shown in Table 1, with the average values for length-width-thickness being 92.59 mm, 63.71 mm and 41.46 mm respectively.

**Table 1.** Results of measurements of physical parameters of potatoes.


The spatial coordinates of the 5-sphere potato particles were set in the EDEM software as shown in Table 2, and the final 5-sphere potato particle model was created as shown in Figure 11. The potato particle model was then generated in the particle factory according to the law of normal distribution.



(2) Soil simulation modelling

In order to determine the parameters of the sandy soil in the potato growing area, a soil with 6% moisture content was used as the test soil sample and the soil parameters for the simulation tests were determined by a combination of measurements and literature review [21,22] as shown in Table 3.

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**Figure 11.** Potato particle model.

**Table 3.** Soil parameters.


After practical research, the potato excavator passed through a soil with soft, nonbonded conditions. To facilitate modelling and reduce unnecessary calculations in the simulation, a single sphere soil particle model was established with a particle radius of 2 mm, as shown in Figure 12.

**Figure 12.** Single sphere particles.

(3) Soil trough simulation modelling

In this experiment, a soil trough with a length, width and height of 2000 × 500 × 300 mm was built with a model number of 50,000 soil particles and a model number of 50 potatoes. The Hertz-Mindlin with JKR model was selected for the discrete element contact model and a simplified pickup model was built as shown in Figure 13.

(4) Determination of contact parameters

In the simulation tests there was contact between soil and soil, soil and potato, potato and potato, pickup device and soil, and pickup device and potato. The material contact parameters can be collated from the literature [23] as shown in Table 4.

**Figure 13.** Soil channel model generated by EDEM pre-processing.


**Table 4.** Physical contact parameters.
