Abstract:
Precision agriculture can play an important role in the development of intelligent agricultural machinery, due to fertilizer saving, low labor intensity, and high work efficiency. Among them, the amount of fertilizer discharge can directly dominate the crop yield. Nevertheless, the fertilizer discharge device was in a closed state during the live broadcast operation. Therefore, the detection of particle fertilizer discharge has been one of the development trends of intelligent and precise operation. Various approaches have been developed to replace granular fertilizers in recent years, such as the rotational speed, doppler effect, dynamic weighing, photoelectric, visual, and electrostatic ones. However, the low accuracy of detection has limited in the rapeseed mechanical direct seeding, due mainly to the large and disordered flow of fertilizer particles. There is a high demand for the real-time detection of high-throughput granular fertilizers during high-speed operations. In this study, the high-throughput particle flow dispersion and diversion serialization of "collision dispersion +sieve diversion +spiral tube constraint" were proposed to fully meet the agronomic requirements of fertilization and high-speed operation in rapeseed direct seeding operation. The high detection accuracy was also obtained under the large and disordered flow of fertilizer particles. A parallel detection device was designed for the diversion order of granular fertilizer using the discrete diversion order mechanism. The key parameters were then determined for the sensing detection structure, uniform fertilizer tube, sieve diversion structure, and spiral tube. A multi-channel signal synchronous acquisition system was also designed for the detection device of rapeseed live broadcast granular fertilizer, according to the multi-channel parallel detection and sensing. A test bench was constructed using a spiral disturbance cone centrifugal fertilizer feeder. The device performance tests were conducted to verify the effectiveness of discrete diversion serialization. The results showed that there was a gradual decrease in the coefficient of variation for each channel diversion of the detection device in an inclined state, as the speed increased when the speed of the fertilizer discharger was 100-130 r/min (fertilizer discharge frequency 361.80-631.60 Hz). The coefficient of variation exceeded 6.08% for each channel diversion under normal field operation with an inclination of 0°-5°. Once the discharge frequency of single-channel fertilizer was 30-80 Hz, the accuracy of the detection device with the spiral tube increased by 7.3 percentage points, compared with the straight tube. The detection accuracy was not less than 90.11% within the speed range of 100~130 r/min after displacement compensation, which was 9.3 percentage points higher than before. The experiment of vibration fertilizer discharge showed that the low-frequency vibration (0-30 Hz) significantly improved the discretization of granular fertilizer and detection accuracy. There was a stable detection accuracy of intermediate frequency vibration (30-110 Hz). High-frequency vibration (110-150 Hz) broke the serialization constraint of granular fertilizer for low detection accuracy. There was no significant impact of different vibration frequencies on the uniformity of the flow distribution in the detection device. The coefficient of variation exceeded 4.98% for each channel diversion. Field experiments showed that there was no significant impact of the light, vibration, and dust on the detection device under normal field operating speeds of 4.3-7.0 km/h. The detection accuracy of the device was not less than 90.05% when the speed of the fertilizer discharger was 100-130 r/min. The detection device can be expected to detect the fertilization operation of the equipment, in order to improve the quality of fertilization operation.