Development of a grain volumetric-flow sensor based on photoelectrical principle

摘要

Field information acquisition plays an important part in Precision Agriculture System. Spatial and temporal variation of grain yield in a field is important field information. It can guide fanners in a reasonable means of production in order to save input and improve efficiency. Thus a grain yield monitor is developed based on photoelectrical sensor. The monitor consists of a LED, a photoelectrical transducer, cables, signal processing circuit, acquisition circuit, etc. The LED and the photoelectrical transducer are equipped in the left and right sides of the clean grain elevator of the combine harvester, respectively. When harvested wheat is threshed, clean grain is lifted to the grain tank by the lifting plates of the elevator, and the grain in a plate will switch off the light from the LED to the transducer. The height of the grain in a plate has a high correlation with the switching off time of the transducer. To measure the switching off time makes it possible to estimate grain yield. The signal processing circuit and acquisition circuit are used to monitor whether the light from the LED is switched off and then to measure the switching off time. And the yield can be calculated from the measured time based on a calibration model. The performance test shows the developed grain yield monitor is practical.