Study On Yield Distribution Information Acquisition Technology For Combine Harvester

This paper introduced the relative technology of yield distribution information acquisition for combine harvester. Researches and experiments were proceed from the grain mass flow measuring, the grain moisture content measuring and the yield monitor software in the paper.By comparing four grain mass flow measuring methods, the method based on weighting was chosen to measure the grain real time flow. By comparing the pros and cons of many kinds of methods for measuring grain moisture content, the capacitance method was chosen to measure grain moisture content. For the chosen methods, the thesis briefly introduced the structure and working principle of grain mass flow measuring device, and also introduced the structure and working principle of device for online measuring grain moisture content.The main researches about the yield monitoring system include three contents.1. The hardware designAn instrument which is used for monitoring and controlling the yield monitoring system was designed for combine harvester. The instrument had been equipped with GPS module,3G wireless data transmission module and CAN bus communication module. All the modules are convenient for the yield monitoring system upgrade.An instrument was designed to collecting the grain mass flow data and collecting the pulse signal generated by the electric motor.By using STC12C5A32S2microchip and AD7745capacitance to digital converter, this article designed a capacitance collecting module to collecting grain moisture content. The module would convert the collected capacitance to digital value, and then send the value to monitor by RS-232serial port. At last the module was packaged with home-made capacitance sensor to make into a capacitance sensor for measuring the grain moisture content.2. The software designA yield monitoring software was developed by VB6.0could be applied to combine harvester based on weighting. The data collected by yield monitor system could be displayed and saved by the software in real time. By computing the collected data the software could display the harvesting total mass, the area, the average yield and so on. The software could draw the grain flow diagram, the working locus diagram of combine and the grain yield map. For the convenience to check the locus diagram, the Gauss-Kruger Projection was used to convert the latitude and longitude coordinate to Gauss coordinate in rectangular plane coordinate system when draw the locus diagram.During the process of drawing the map, the map will move itself far away from the border of interface to ensure the real time curve displaying normally before the curve arrives the border of interface. After finishing drawing, the map could be dragged in the interface freely to check the whole map. The software could compute the saved experiment data to simulate the harvesting status as combine harvester was working in the field and redraw the yield map acquired from the real harvesting.3. The experimentThe experiment condition and procedure are elaborated in the paper. A large number of researches have proved that the yield monitoring system can reach good measuring accuracy. The yield monitoring precision was less than2%in laboratory and less than3%in field. The relative error of the wheat moisture content is less than1.5%in laboratory.