勺夹式花生小区单粒精量播种单体设计与试验

针对花生小区播种机播种尺寸差异较大种子时存在适应性差、单粒精播粒距合格率低等问题，该研究设计了一种基于STM32单片机控制的勺夹式花生小区单粒精量播种单体。采用先充种后投种的模式，利用夹持空间可调节的勺夹式排种器向双格盘播种总成内单粒排种，由STM32单片机控制光电传感器、增量式编码器以及步进电机等元件，实现有序充种和投种。根据播种时花生种子的运动轨迹，确定影响机具作业性能的主要参数为机具作业速度和投种口离地高度。以提高单粒精播粒距合格率，降低播种漏播率、重播率、破损率为目标，对机具作业参数进行单因素与双因素数值模拟分析，探究了机具作业速度、投种口离地高度以及二者交互作用对播种性能的影响。试验结果表明，机具作业速度0.9 m/s、投种口离地高度15 cm时的播种效果最佳：粒距合格率为96.20%、重播率为2.97%、破损率为0.50%、漏播率为0.33%，整机通过性和适用性良好，能够满足小区育种试验要求。该研究可为花生小区精量播种技术研发提供参考。

Design and experiments of a precision sowing unit with the spoon clip for single peanut seed planting in plot

Seed sowing cannot fully meet the large and different sizes of the peanut plot in recent years. It is a high demand for high adaptability and qualification rate in the precision sowing of a single seed. In this study, a spoon-clip type of precision sowing unit was developed for the single seed in the peanut plot using STM32 single-chip microcomputer control system. A systematic investigation was made on the structures and parameters of key components, such as the ditching, seed metering, and seed distribution, as well as the hardware and software of the precision sowing control system. The main structural parameters and operation mode were then determined in the key components, such as the sowing monomer trenching, seed metering, and seed distribution. The mode of filling seeds was adopted first, and then the dropping seeds were adjusted for the clamping space of the scoop-clamp type seed metering device. The motor drove the seed metering device to feed a single seed into the double-grid seeding assembly. The detection elements (photoelectric sensor, and incremental encoder), and the executive elements (stepping motor) were controlled to realize the orderly filling and seeding in the double-grid seeding assembly. A control system was then designed using STM32 single-chip microcomputer. Furthermore, the system mainboard, power supply, photoelectric sensor, speed sensor, stepping motor, and hardware parts were selected to design the circuit, according to the working mode of the load. The C language was used to realize the detection and execution of the system in the process of uniform seed metering, precise seed distribution, orderly seed sowing, and efficient seed clearing in the single seed sowing unit. The step angle and the driver fraction were set to adjust the number of pulses for the desired angle, according to the pulse regulation mechanism of the stepping motor. The movement track was optimized for the single precision seeding unit in the scoop-clip peanut plot. The influencing parameters were determined as the operating performance of the machine, including the operation speed of the machine and the height of the seed opening from the ground. A single- and double-factor numerical simulation was carried out for the operation parameters of the machines, in order to improve the qualified index of single precision sowing seed spacing for the less missed sowing, replanting, and damage index during sowing. The influencing mechanism of seeding performance was explored to clarify the operation speed in the machines, the height of the seed opening from the ground, and the interaction between them. The test showed that the seeding effect of the machine was the best when the operating speed of the machine was 0.9 m/s, and the height of the seed opening from the ground was 15 cm. Specifically, the qualified rate of the seed spacing was 96.2%, the re-seeding rate was 2.97%, the broken rate was 0.50%, and the miss-seeding rate was 0.33%. The high trafficability and applicability of the whole machine can fully meet the requirements of the plot breeding test. This finding can also provide a strong reference to developing precision seeding technology in peanut plots.