Design And Test Of Rotary-throwing Yield Measuring Device For Combine Harvester

With the continuous improvement of China’s agricultural modernization and the strengthening of agricultural science and technology innovation,precision agriculture has been developed rapidly.The establishment of grain yield map,as an important part of precision agriculture,can provide information on the variation of grain yield distribution in the field and can evaluate the field management technology for precise control of agricultural production.As a key part of the grain yield map establishment,the accuracy and anti-interference ability of the grain flow detection device play a decisive role in the accuracy of the yield distribution map.In this paper,a rotary throwing-based grain mass flow detection method is designed to improve the yield measurement accuracy problem caused by the tilting of throwing discs in the existing rotary throwing grain flow detection device based on the Koch force measurement principle,and the main research contents are as follows:1.Based on the structure of rotary throwing grain flow measurement based on Koch’s force,a grain flow measurement method based on the rotary throwing measurement principle is studied and designed,the basic structure of the measurement device and the workflow are introduced,and the mathematical model between the grain mass flow and the disc torque is established.The disc torque is basically uncoupled from the background vibration of the combine harvester,effectively avoiding the interference and influence of the main components of the combine harvester background vibration and essentially improving its anti-interference performance.2.The selection and design of the hardware structure of the rotary-throwing yield measurement device,as well as the mechanical structure design of the throwing disc,and the adaptation design and modification of the grain closing device based on the experimental combine harvester platform were carried out.3.The software of the rotary throwing grain flow measurement device was designed in relation to it.The torque sensor signal and the attitude sensor signal are collected and analyzed,and the wavelet analysis program based on Mallat algorithm is written to denoise the collected signals.Lab VIEW software is used to write the upper computer program of the real-time grain flow acquisition and processing system,which has the functions of data acquisition and processing,data display and storage.4.The test platform of the rotary throwing grain flow measurement device was built,and the correctness of the linear mathematical model between grain mass flow and disc torque was verified by bench test.The sensor attitude error was introduced to correct the error of the yield measurement device,and the impact of the sensor tilt angle on the grain mass flow monitoring results was analyzed by the bench test.The test showed that when the tilt angle of the disc increased significantly,it had a significant impact on the grain flow value collected by the sensor,and the measurement error reached about 10% at a tilt angle greater than 15°.5.Field tests were conducted on the rotary throwing grain mass flow sensor,and the test results showed that the grain flow measurement error was within 5%,which could meet the actual yield measurement requirements of combine harvesters.Meanwhile,after adding Mallat wavelet analysis algorithm,the grain flow detection accuracy can be improved by 1%-2%.