| In lunar exploration,the determination of lunar mechanical parameters is an important factor affecting the establishment of lunar research stations.A large amount of lunar soil is required to obtain lunar soil parameters,but lunar soil is precious,and the inverse analysis method is an important means to study the identification of lunar soil mechanical parameters.At the same time,there are characteristics such as stratification and unevenness on the lunar surface,so in the soft landing of the lunar surface of previous landers,the lunar soil parameters of the landing land are inverted through data information,which has important scientific research and application value for the study of lunar soil characteristics.In this thesis,based on the landing video data of the landing camera,combined with the lander feature information,image analysis technology is used to construct the footpad trajectory technology during landing,and the reliability of the footpad trajectory acquisition technology is verified by indoor experiment.Combined with the existing impact dynamic analysis model of the foot mat in the research group,the density and shear strength of the lunar soil in the CE-4 landing area were obtained by inversion analysis method,and the main work is as follows:(1)A method for extracting displacement parameters from lander impact soil images is proposed.Build a lander impact test device to collect the landing map frequency during the lander impact process;By analyzing the morphological characteristics of the lander-soil interaction,the map frequency data of the impact process were processed.In order to extract the change area of adjacent frames,fuse the images of adjacent frames,extract the area of interest of the change area,use the contour coordinates of the area of interest to obtain the frame-by-frame change,and finally obtain the lander impact soil trajectory equation,which can effectively estimate the vertical displacement of the foot pad.(2)Established the correlation expression“k”of the image processing technology and the time history curve of the measured data.The trajectory equation was formed by using the displacement parameter extraction method of the lander impact soil image and the experimental measurement displacement extraction method.Finally,the trajectory equations of the two measurement methods are fitted separately,and the correlation expression“k”between the two is obtained.(3)An inversion analysis method based on shock dynamics model was studied.According to the measured data of the lander’s impact soil,combined with the golden section method and the lander impact dynamic model,the displacement inverse analysis model and the soil mechanical parameters to be inverted were determined.The inversion analysis of the mechanical parameters of the lander impact soil was determined by the displacement inverse analysis method,and the internal friction angle was determined to be 49.6°,the density was1.583g/cm~3and the relative compactness was 0.40,which was in line with the actual soil mechanical parameters,which provided a reference for the subsequent inversion of the mechanical parameters of the moonback lunar soil in the CE-4 landing area.(4)The displacement extraction method and inversion analysis method were used to invert the mechanical parameters of CE-April dorsal lunar soil.Based on the above research results and the mechanical parameter inversion method,and based on the frequency data of the CE-4 landing process,the mechanical parameters of the lunar soil in the CE-4 landing area were analyzed inverted,and the lunar soil parameters of the Chang’e-4 landing area were determined.The final inversion of the lunar soil parameters was0.65 relative compactness,37.6°friction angle in the lunar soil,and 1.775g/cm~3in the lunar soil.At the same time,an ABAQUS simulation model is established,which verifies the rationality of the inversion of the mechanical parameters and proves the effectiveness of this method. |
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