基于分散机制的条播小麦播量监测装置设计与试验

Design and Experiment of Strip-sowing Wheat Sowing Quantity Monitoring Device Based on Dispersion Mechanism

摘要:

针对小麦播种过程中因播量增大及高效播种产生的排种频率过高而导致高速种子流监测精度不足的问题，提出了一种将高频率种子流分散为多路低频率种子流并行监测的方法，设计了一种基于分散机制与对射式红外光电传感器相结合的小麦种子流监测装置。通过分析种子流在分散装置中的运动状态，建立了种子流在分散装置内的运动模型，确定了影响分散性能的关键因素。利用离散元法(Discrete element method，EDEM)仿真麦种通过分散装置的动态过程并对参数优化，获得最优参数为上分散板半径52.70mm、上分散板倾角5.41°、下分散板半径64.95mm、下分散板倾角7.48°和两分散板垂直距离13.59mm，而分散均匀性变异系数为21.06%。采用最优参数进行分散性能台架验证试验，结果显示分散均匀性变异系数不大于21.94%，台架与仿真试验结果相比相对误差不超过5%。采用对射式红外光电传感器采集种子掉落信号，经电容滤波、双级放大、半波整流、电压比较及单稳态触发处理，获得8路独立且可供单片机捕捉的脉冲信号，单片机通过中断服务程序对各通道种子计数并累计求和。搭建了高频率小麦播量监测系统及监测精度试验台，试验结果表明，加入补偿后播种量在375kg/hm2内，监测精度不低于95.34%。该监测装置可为条播小麦高效精量播种的播量监测研究提供技术支持。

Abstract:

Aiming at the problem of insufficient monitoring accuracy of high-speed seed flow caused by increased seeding rates and high-efficiency seeding during wheat sowing, a method was proposed to disperse high-frequency seed flow into multiple low-frequency seed flows for parallel monitoring. A wheat seed flow monitoring device, combining a dispersion mechanism with through-beam infrared photoelectric sensors, was designed. By analyzing the movement of the seed flow within the dispersion device, a motion model was established, identifying the key factors affecting dynamic process of wheat seeds passing through the dispersion device was simulated by using the discrete element method (EDEM). Firstly, parameter optimization tests were conducted on a single dispersion plate, yielding optimal mechanism parameters: an upper dispersion plate radius of 52.70mm and an angle of 5.41°. Building on this parameter optimization tests for a double dispersion plate were performed, resulting in optimal parameters of a lower dispersion plate radius of 64.95mm, an inclination angle of 7.48°, and a vertical distance of 13.59mm between the two plates. Under these conditions, the coefficient of variation for dispersion uniformity did not exceed 21.06%. A bench test of the dispersion performance was conducted by using the optimal parameters. Results showed that the coefficient of variation for dispersion uniformity was no more than 21.94%, with an error between bench test and simulation results of less than 5%. A collimated infrared photoelectric sensor was employed to collect seed drop signals. After capacitor filtering, two-stage amplification, half-wave rectification, voltage comparison, and monostable triggering processing, eight independent pulse signals were generated, which could be captured by the microcontroller. The microcontroller, via an interrupt service routine, counted seeds in each channel and accumulated the total, thereby establishing a high-frequency wheat seeding amount monitoring system. Bench tests of monitoring accuracy demonstrated that accuracy was no less than 95.34% within a seeding rate of 375kg/hm2. This monitoring device can provide technical support for research on accurate and efficient seeding volume monitoring in strip-sown wheat.