## 2 Materials and Methods
### Determination of the Uniformity of Lateral Wind Generated by the Air Flow Generator  
In this study, lateral winds of different velocities were generated using an air flow generation stand (Figure 2). Two axial fans ML 1004 DT (1) (Electrovent, Soiano, Italy) with impeller diameters of 1000 mm were mounted in the frame of the stand. The impellers consist of 10 plastic blades. The fan impellers were driven by two electric motors 7 SM3 160L4 (power, 15 kW, and rotation, 1465 min\({}^{-1}\)) (Smem, Monza, Italy). An air velocity straightener was installed in front of the impellers at the front of the stand. Two Delta VFD-C2000 voltage-to-frequency converters (Delta Electronics, Taipei, Taiwan) were used to change the rotational speed of the fan impellers. The air velocity (i.e., lateral wind) velocity varied from 2 m s\({}^{-1}\) to 8 m s\({}^{-1}\) in 2 m s\({}^{-1}\) increments. Before the spray tests, the variation in the wind velocity generated by the air flow generator in the x-axis direction was determined (Figure 2). For the wind velocity measurements, 10 thermo-anemometric sensors were used and mounted on a specially designed stand (5). It can vary the height of the sensors from 0.2 to 1.2 m and take measurements precisely over a 2 m zone. The wind velocity was measured over a time interval of about 40 s and each sensor recorded about 400 measurements. The measurement data recorded by the sensors are transmitted to the control unit (2) and from there to the AirLab software package installed on the computer (3). Air velocity measurements were taken at 14 different locations, shown as red dots in Figure 2 (I-XIV). The first measurement (I) was taken at a distance of one meter from the air flow generator, at the first row of artificial plants. The last measurement was taken at 11 m from the air flow generator (XIV). At each distance, the air velocity was measured at 3 different heights of 0.5, 1.0, and 1.2 m (Figure 3). The numerical values obtained were statistically processed and the results are shown in Tables 1 and 2. It can be observed that the numerical values of the wind velocity recorded by the sensors decrease slightly with distance from the fans. In addition, artificial plants induce irregularities in the air flow, i.e., vortexes. The air velocity at point I was measured and the average of the 10 sensors was found to be 2.2 m s\({}^{-1}\), indicating that the desired lateral wind of 2 m s\({}^{-1}\) was achieved (Figure 4). Selecting the results from point VII and averaging the 10 sensors, the air flow velocity is 1.7 m s\({}^{-1}\), and the average of the 10 sensors at point XIV is 1.5 m s\({}^{-1}\). A similar trend can be seen when analyzing the higher air velocity results (8 m s\({}^{-1}\)) (Figure 5). Averaging the values recorded by the 10 sensors, the air velocity at measurement point I is 7.5 m s\({}^{-1}\). As the distance from the air flow generator increases, the numerical values of the air velocity decrease. When the sensors were moved 4.5 m away from the air flow generator (point VII), their average air velocity was found to be 6.6 m s\({}^{-1}\). Measurements taken 11 m away from the air flow generator (point XIV) showed that the air velocity averaged at 4.8 m s\({}^{-1}\). Figure 4: Air velocity measurement results at 0.5 m from the ground when the air velocity selected was 2 m s\({}^{-1}\). Figure 5: Air velocity measurement results at 0.5 m from the ground when the air velocity selected was 8 m s\({}^{-1}\). Figure 6: Artificial plant with water-sensitive paper attachment points: 1—water-sensitive paper (WSP); 2—net; 3—pillar. As the spacing between bushes in the gardens is between 1.5 and 2 m, the width of the row spacing reaches 3 m [56], so in this study, the artificial plants were arranged in 6 rows of two plants each (Figure 7). The intra-row spacing was 1.5 m and the inter-row spacing was 3 m. The robot sprayer (2) drove at a speed of 1.2 m s\({}^{-1}\) between the first and second rows of plants during the test and sprayed on the artificial plants in the first row (Figure 6).