The Research Of The Methods Of Measuring Grain Flow On Real Time For Combines

The research of Precision Agriculture that is an agricultural science revolution has made more and more people s attention along with information technology applying in agriculture. It is the bas of PA that using the spatial variable information of field to bear on decisions associated with agricultural production. This needs the support of technology of obtaining field yield information and making yield map.In our country,the research of Precision Agriculture is in beginning stage now,especially in basic theory and method studying. Yield-measurement is a key technology of desiderating resolution in Precision Agriculture system. It is necessary in our country that studying the methods of grain-flow-measurement in lab.Many methods of measuring grain flow on combines are presented in the literature,such as volumetric method,impact sensor,radiometric method and capacitor sensor,etc. There are some disadvantages needing resolution in application about these methods,although they have some feature. In this paper,two kinds of grain-flow-measurement-systems for combine harvesters are developed in laboratory,radiometric sensor using the principle of the absorption of y-rays by grains and piezoelectric crystal sensor using the principle of impact. The static experience about the absorption of y-rays by different grains has been made. Furthermore we made the dynamic calibrating and testing experience for two kinds of systems,analyzed and compared the precisions of two methods,and found some correlation factor of affecting measurement precision. The test results show that the measurement errors of y-ray measurement system are within 2%,and the errors of piezoelectric crystal measurement system are about 5%. It indicates that the systems are feasible. In the design of software,we adopted virtual instrument,and selected PCI-1200 as the DAQ card.This paper firstly makes experience study of grain flow dynamic measurement for combines in China. Piezoelectric crystal sensor used in impulse measurement method is a try and has not been presented in any reports. These study work establish theory basis for developing homemade combine harvesters with vield monitor.