Junhao Huang

Nowadays, unmanned aerial vehicles (UAVs) play a pivotal role in agricultural production. In scenarios involving the release of particulate materials, the precision of quantity monitors for the storage tank of UAVs directly impacts its operational accuracy. Therefore, this paper introduces a novel noise-mitigation design for agricultural UAVs’ quantity monitors, utilizing differential weighing sensors. The design effectively addresses three primary noise sources: sensor-intrinsic noise, vibration noise, and weight-loading uncertainty. Additionally, two comprehensive data processing methods are proposed for noise reduction: the first combines the Butterworth low-pass filter, the Kalman filter, and the moving average filter (BKM), while the second integrates the Least Mean Squares (LMS) adaptive filter, the Kalman filter, and the moving average filter (LKM). Rigorous data processing has been conducted, and the monitor’s performance has been assessed in three UAV typical states: static, hovering, and flighting. Specifically, compared to the BKM, the LKM’s maximum relative error ranges between 1.24% and 2.74%, with an average relative error of 0.31%~0.58% when the UAV was in a hovering state. In flight mode, the LKM’s maximum relative error varies from 1.68% to 10.06%, while the average relative error ranges between 0.74% and 2.54%. Furthermore, LKM can effectively suppress noise interference near 75 Hz and 150 Hz. The results reveal that the LKM technology demonstrated superior adaptability to noise and effectively mitigates its impact in the quantity monitoring for storage tank of agricultural UAVs.

Unmanned aerial vehicles (UAVs) are widely being used to spread granular fertilizer in China. Granular fertilizer spreaders equipped with UAVs are mainly centrifugal disc-type and pneumatic. The multichannel pneumatic granular fertilizer spreaders (MPGFSs) have a banded fertilizer deposition distribution pattern, which are more suitable for variable rate fertilization than the circular deposition distribution pattern of disc-type granular fertilizer spreaders (DGFSs). However, the existing MPGFS has the disadvantage of inconsistent discharge rate of each channel, which affects the uniformity of fertilization. In order to explore the causes of inconsistent discharge rate of each channel, the discrete element method (DEM) and bench test were performed to analysis the discharge process of the fluted roller fertilizing apparatus and distribution of fertilizer in axial direction of fluted roller. The computational fluid dynamics (CFD) was used to simulate the airflow field of pneumatic system to analyze the influence of airflow on the movement of fertilizer particles. The simulation results of the discharge process of the fluted roller fertilizing apparatus showed that the filling velocity at the axial ends of the fluted roller fertilizing apparatus was lower than that of the middle. The reason was that the filling capacity was weak near the wall. The simulated results of the airflow field without partitions showed that the airflow provided by the axial flow fan was rotational, and this caused the particles to move irregularly in the throat, resulting in inconsistency discharge rate of each channel. Based on the analysis of reasons of inconsistent discharge rate of each channel, a MPGFS with partitions in the throat was developed. The discharge rate bench tests were carried out to optimize the partition spacing parameters, and fertilization test was performed to test the performance of the improved MPGFS. The discharge rate test results showed better consistency with partition. The coefficient of variation (CV) of the discharge rate of each channel was 20.16% without the partition and 7.70% with the optimal partition. The fertilizer spreading uniformity test results shown that the CV of spreading uniformity of MPGFS without partitions was 15.32%, and that MPGFS with partitions was 8.69%. The partitions design was beneficial to improve the consistency of each channel discharge rate and the uniformity of fertilization. The finding can provide a strong reference to design the MPGFS. Keywords: UAV, discharge rate, fertilizer spreader, DEM, CFD DOI: 10.25165/j.ijabe.20231604.7129 Citation: Wang X W, Jiang R, Zhou Z Y, Song C C, Luo X W, Bao R F, et al. Discharge rate consistency of each channel for UAV-based pneumatic granular fertilizer spreader. Int J Agric & Biol Eng, 2023; 16(4): 20-28