Research On Soil Cone Index Of Farmland And Design Of Measuring Device

With the continuous improvement of the degree of mechanization of agriculture,the problem of soil compaction has become more and more serious.Among them,the conical index is an important indicator to reflect soil compaction.It is of great significance to find the main influencing factors and explore the relationship.In addition,the development of a portable,cost-effective and multi-functional precision measuring device is also necessary for agricultural production.Firstly,the discrete element numerical simulation software was used to model and simulate the test process of conical exponential index.The relationship between penetration speed and cone index measurement and the relationship between soil conic index and soil bulk dens ity,soil moisture content and penetration depth were investigated.Using software to fit the simulation data,the results show that the penetration speed is less than the depth factor in the range of 10-50mm/s,and the influence of the depth can be ignored.When the bulk density and penetration depth are constant,the conic index increases first and then decreases with the increase of soil water content,and the maximum point appears between 10% and 15%,which increases with soil bulk density.More obvious;for a certain bulk density,for soils with different water contents,as the penetration depth increases,the conic index increases,and the increase trend can be fitted by a quadratic curve whose growth rate is gradually reduced,and the bulk density is At 1.4 g·cm-3 or 1.5 g·cm-3,the conic index increases gently with increasing depth.When the bulk density is 1.6 g·cm-3,the conic index increases with depth and the latter increases.The rate of growth is about 5-6 times that of the former.Then the test platform is built and tested by the response surface method.The test results a re basically consistent with simulation results,and the multivariate quadratic regression equation of the conical index on water content,bulk density and penetration depth is established.The test results also show The JKR contact model is a better model for simulating contact between soil particles than the default Hertz-Mindlin(no slip)model.Finally,comprehensive research results and ASAE standards complete instrument ha rdware design,software design,structural design,system testing,and prototype field trials.According to the requirements of use,in terms of hardware,the STM32 is the main controller,combined with the pull pressure sensor,laser ranging module,tempe rature sensor,SD card storage module and other multi-peripherals to complete the data measurement and data transmission and storage of the cone indexer.And other functions.In software,based on MDK5 integrated development environment,STM32 standard peripheral library and ?C/OSIII embedded operating system to complete application programming,the system realizes the function of data acquisition and processing,transplanting graphic software library ST-EMWIN to optimize human-computer interaction.The file management system is introduced to realize the storage and transmission of data,and the upper computer software matched with the instrument is developed by using MATLAB software to realize post-processing of data.According to the industrial design and use requirements,the structure of the instrument is designed and the finite element analysis is performed on the main stressed components.Under the existing experimental conditions,the instrument test and field test are completed.The measurement result s show that the system can meet the design and use requirements in various performance indicators such as range,error and smooth operation.