Research On The Development Of Grain Yield Monitoring System Based On Pressure Sensors

Grain yield distribution information is one of the most important information in digital agriculture,and the development of grain yield monitoring system has always been the focus and difficulty of obtaining grain yield distribution information in the process of grain harvesting.Different grain yield monitoring systems have been designed by researchers with various means,but they have not been popularized and applied in China due to the influence of measurement accuracy and model matching.In order to improve the accuracy and adaptability of on-line monitoring of grain yield,a grain yield monitoring system based on the principle of grain flow pressure was designed in this paper.The mathematical model of grain yield and grain flow pressure was established,and the grain yield monitoring test bench was set up and the laboratory test was carried out.On the basis of bench test,the structure parameters of grain flow monitoring device were optimized.In addition,the grain yield monitoring system was applied to field work to verify its actual monitoring effect of yield.The yield distribution map was generated,which provided a decision basis for the management of subsequent field operations.The main research contents of this paper were as follows:(1)The mathematical model of grain yield and grain flow pressure was built,and the overall structure of pressure-type grain yield monitoring system was determined.The monitoring system was mainly composed of grain flow monitoring device,positioning device,header height detection switch,core processor and human-machine interaction device.The above work provided a new method and a new device for the on-line monitoring of grain yield.(2)The hardware of pressure-type grain yield monitoring system was designed.Combined with the requirements of system functions,the hardware design of signal acquisition,data processing and data display was completed.The system hardware mainly includes the pressure sensor and moisture sensor in the grain flow monitoring,the tension sensor in the header height detection switch,the positioning device,the core processor,and the human-machine interaction device.The hardware selection,circuit design and overall system construction of these hardware has been completed.(3)The software of pressure-type grain yield monitoring system was developed.Based on MDK5 development platform,the software code of grain yield monitoring system was designed with modular idea.The software included: system initialization,parameter setting,data acquisition and processing,data display and data storage.The human-machine interaction interface of the system was designed by USART HMI software.It realized the real-time measurement,display and storage of dry/wet grain yield information during the operation of grain harvester.(4)A test bed for monitoring grain yield had been built.It was mainly composed of grain flow monitoring device,auger,feeding box,insert plate,three-phase AC motor,reducer,bench and so on.Laboratory bench tests were carried out to verify the accuracy and stability of the main sensors of the pressure-type grain yield monitoring system.The experimental results showed that the monitoring error of grain moisture content was less than 1.47%,and the monitoring error of grain yield was less than 4.24%,which provided data support for the subsequent system optimization.(5)The optimization research of pressure-type grain yield monitoring system was carried out.Response surface analysis was used to determine the optimal parameter combination of the grain flow monitoring device structure as the number of sensors 5,the sensor installation position 0.24 cm,the horizontal Angle of the monitoring device 5°,and the verification test of the optimal parameter combination was carried out.The results showed that the measurement error of grain yield monitoring system was 3.27%,which met the precision requirement of grain yield monitoring.(6)The grain yield monitoring system was applied to field harvesting to verify its actual monitoring effect of yield.The field experimental results showed that the error of the field yield measurement was 5.28%.The grain yield monitoring data of the field experiment were filtered and interpolated,and the yield distribution map was finally generated.The yield distribution map could provide decision basis for subsequent variable sowing and fertilizer management.