# Simulation of Sowing Precision in Laboratory Conditions
## 2 Materials and Methods
### Tests under Operating Conditions  
For this purpose, acceleration transducers (triaxial accelerometers model 356B10) were mounted on the precision planter (with 8 row units), with pneumatic seed meters, vertical discs with holes, and lamellar singulator. From experimental practice, it is known that the vibrations in the transverse direction are much smaller than those in the other two directions: longitudinal and vertical [61; 62; 63], and, thus, the acceleration measurements were performed on three channels as follows:  
* On the SO, SV, and BV row unit in the horizontal and vertical direction;
* On the planter's frame only on the vertical direction. The acquisition of the raw experimental data was obtained with the help of the following measurement chain composed of:  
1. Acceleration transducer (Figure 3);  
Table 1 shows the specifications of the PCB triaxial accelerometer, model 356B10. 2. PCB signal conditioner model 480B21 with a frequency range of up to 100 kHz (Figure 4);  
Figure 3: Scheme of PCB triaxial accelerometer model 356B10 [64]. Figure 2: Scheme of the studied row unit’s seed meter: (**a**) Top view; (**b**) Lateral view; (1) vacuum hose; (2) depression chamber; (3) seed meter cover; (4) lamellar singulator; (5) agitator; (6) seed feeding chamber; and (7) seed meter shaft. Table 2 shows the specifications of PCB signal conditioner model 480B21. 3. Data recording module (NI 9233 data acquisition device + computer); The NI USB-9233 data acquisition device provides a USB interface for four channels of 24-bit analog inputs with integrated signal conditioning, consisting of two components: an NI 9233 module and an NI USB-9162 carrier (Figure 5);
4. Laptop with LabVIEW data acquisition software. The raw data acquisition software was developed in LabVIEW and contains the task of data acquisition and calibration of the three measurement channels from the accelerometer (DAQ Assistant), a virtual tool for real-time display of the power spectrum of vibrations on the 3 channels (Power Spectrum), a virtual tool for calculating real-time RMS values (Vibration Level), and a virtual tool for saving data in ASCII format. Within the program developed in LabVIEW, a data acquisition task was performed on three analog channels. The acquired data was filtered (low-pass filter to 5 Hz) and saved in an ASCII file. \begin{table}
\begin{tabular}{c c} \hline \hline
**Specifications** & **PCB Model 356B10** \\ \hline Sensitivity, (mV/(m/s\({}^{2}\))) & 0.1 \\ Frequency Range (\(\pm\)5\%) (y or z axis), (Hz) & 2–10,000 \\ Frequency Range (\(\pm\)5\%) (x axis), (Hz) & 2–7000 \\ Resonant Frequency, (Hz) & \(\geq\)55 \\ Output Impedance, (\(\Omega\)) & \(\leq\)200 \\ Dimensions L \(\times\) 1 \(\times\) h, (mm) & 10.2 \(\times\) 10.2 \(\times\) 10.2 \\ Weight, (g) & 4 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Specifications of the PCB triaxial accelerometer model 356B10 [64]. Figure 4: Scheme of PCB signal conditioner model 480B21 [65]. Figure 5: Scheme of NI USB-9233 data acquisition device with 4 analog input channels [66]. The signals were recorded in the computer, and their subsequent processing was performed in the laboratory, through the following steps:  
* Channel demultiplications;
* Graphic editing;
* Obtaining the power spectrum for the registered acceleration signals. The amplitude of vibrations recorded on the row units was mainly correlated with the degree of soil grinding. Determination of the degree of soil grinding, \(G_{ms}\), was the proportion by weight of soil fractions with lump sizes of less than 20 mm, between 20 and 50 mm, 50 and 100 mm, and more than 100 mm in relation to the mass of the soil sample. The degree of grinding was calculated in % with the relation (according to SR 13230-94) [67]:  
\[G_{ms}=\frac{\sum_{1}^{n}\frac{m_{xi}}{m_{ti}}}{n_{me}}\cdot 100 \tag{1}\]  
where:  
\(m_{xi}\)--measured weight of soil lumps with reference lump size: