## 3 Design of Essential Parts of the Seed Dispenser  
### Parameterization of Seed Disks  
The seed-discharging disk is the core component of the pneumatic precision seeder, the performance of the seed discharging disk directly determines the seed discharging version of the seeder [19]. The structure of the seed discharge disk is shown in Figure 3. The design of the seed discharge disk mainly includes the following aspects. 1. Determination and analysis of the diameter of the seed discharge tray The diameter of the seed-discharging disk affects the size and working performance of the whole seed-discharging device. We propose idealised assumptions to better study the diameter of the rowing disks: that the seeds are homogeneous and consistent, that there are no external disturbances, and that mechanical conditions such as wear of the disks are not taken into account. The real process may not strictly follow the theoretical model. In the seed-discharging stage, assuming that the seed-discharging time of a single hole is t1, it can be found according to the relationship between the speed of the seed-discharging disk and the seed-filling time, \[\left\{ \begin{array}{l}v_{c}=\frac{\pi d_{c}n}{60}\\ l_{c}=\theta\frac{d_{c}}{c}\\ t_{1}=\frac{l_{c}^{2}}{v_{c}}\end{array} \right.\] (3) where: \(d_{c}\)--diameter of seed discharge disk, mm \(n\)--rotational speed of seed discharge disk, rpm \(v_{c}\)--line speed of seed discharge disk, m/s \(\theta\)--seed-filling angle size, rad  
Figure 3: Three-dimensional structure of seed disk. 1. Linear serrated structure, 2. drive shaft connection holes, 3. type holes. \(l_{c}\)--arc length of the seed-filled area, mm  
\(t_{1}\)--seed filling time, s  
From Equation (3) [20],  
\[t_{1}=\frac{30\theta}{\pi n} \tag{4}\]  
The longer the seed discharge disk-shaped hole stays in the seed-filling area, the more favorable it is for the disturbance and adsorption of seeds, which can effectively reduce the leakage rate of the seeder. As can be seen from Equation (4), the root-filling time \(t_{1}\) is only affected by the seed-filling angle and the rotational speed of the seed-discharging disk. It has no relationship with the size of the diameter of the source-discharging disk. Therefore, changing the diameter of the seeding disk does not allow the type holes to remain in the seeding area for a longer period, nor does it improve seeding performance. Therefore, the diameter of the seed discharge disk can be designed according to the overall structural parameters of the seeder. Now on the market, pneumatic seeder seed disk diameter sizes are generally within 80-260 mm [21]. To match the seeding device and the overall parameters of the seeder requirements, this paper selects the seed discharge disk diameter size of 160 mm and the disk thickness of 1 mm. Determination and analysis of the number of holes  
The number of holes in the seed tray significantly impacts the seeding hole spacing [22]. According to the principal analysis of the seeding device, we can get the relationship between the centerline speed of the holes and the travel speed of the seeding device as follows:  
\[ \begin{cases}v_{x}=\frac{\pi md_{x}}{60}\\ v_{b}=\frac{p(1-8)v_{x}l_{b}}{\pi d_{x}}\end{cases}  \tag{5}\]  
where:  
\(d_{x}\)--diameter where the hole is located, mm  
\(v_{b}\)--the speed at which the seeding device proceeds, m/s  
\(\delta\)--coefficient of slip of the ground wheel of the seeding device  
\(l_{b}\)--seeding device hole spacing, m  
\(v_{x}\)--linear velocity at the center of the typed hole on the seed discharge tray, m/s  
\(p\)--number of type holes on the seed discharge disk, \(p\)  
It follows from Equation (5):  
\[p=\frac{60v_{b}}{(1-8)nl_{b}} \tag{6}\]  
In the literature it can be seen [23] that for cabbage in planting, hole spacing requirements are 80-130 mm, where set hole spacing \(l_{b}\) is 110 mm, the slip coefficient of the ground wheel of the supporting seeding device is set at 0.8, rotational speed n is 50 rpm, and walking speed is 2 m/s.