Abstract: Aiming at the problems of complex structure and high cost of the wheat loss monitoring sensor, the motion characteristics of different materials in the harvester cleaning and discharging port were studied, and the law of the impact of wheat and straw on the sensitive plate was revealed. Based on the mechanical properties, an experimental device for monitoring the cleaning loss of wheat harvester was designed. The discrete element analysis software EDEM was used to analyze the force generated by the impact of wheat grains, 50 mm straw and 100 mm straw on the sensitive plate, and the change curve of the contact force was analyzed. In order to enhance the accuracy of signal acquisition, two piezoelectric sensors were connected in series, which increased the signal of loss. The mechanical structure and control system of the loss monitoring test bench were designed, so that the monitoring device simulated the cleaning and removal process of the harvester and could monitor the signal in real time, which effectively improved the monitoring efficiency. Finally, through the monitoring test of material movement loss at different heights, it was concluded that the sensor recognition was more accurate at a height of 300 mm, the recognition rate of wheat grains reached 98.4%, and the overall monitoring error was less than 5%. The loss monitoring test device can meet the design purpose and requirements.

Key words: discrete element method, piezoelectric sensor, wheat, loss monitoring

摘要： 针对小麦损失监测传感器结构复杂、成本较高的问题，对收获机清选排杂口不同物料运动特性进行研究，揭示小麦与秸秆撞击敏感板的作用规律，从清选抛出物冲击敏感板的力学特性出发，设计一种小麦收获机清选损失监测试验装置。通过离散元分析软件EDEM分析小麦籽粒、50 mm秸秆、100 mm秸秆撞击敏感板产生的作用力，分析接触力变化曲线，证明可通过判断物料撞击敏感板产生的信号进行损失监测。为增强信号采集准确率，采用两片压电传感器串联的方式，增大损失信号。设计损失监测试验台机械结构及控制系统，使监测装置模拟收获机清选排杂过程且可以实时监测信号，有效提高监测效率。最后，通过不同高度物料运动损失监测试验，得出300 mm高度下传感器识别较为精准，对小麦籽粒的识别率达到98.4%，整体监测误差小于5%，损失监测试验装置能够达到设计目的和要求。

关键词: 离散元方法, 压电传感器, 小麦, 损失监测