Dynamics Modeling And Optimization Of Multi-body System Of Paddy Field Leveler

Modern rice cultivation techniques have a high level of paddy field formation,and the improvement of flatness is beneficial to water saving,fertilizer and crop yield.Paddy field grading machine is simple,cost-effective,the effect is better,suitable for China's paddy field formation requirements.To this end,the South China Agricultural University developed a paddy field laser grader,it can be complex in the paddy field environment,according to the body by the interference automatically adjust the height and inclination of the ground shovel,to maintain the level and maintain the set height to achieve the purpose of leveling the paddy field.And after a large area of promotion,precision can be controlled within 3cm,and achieved good economic and social benefits.However,in the popularization practice,it is found that there are some main problems in the paddy field grader: when the grader speed is slow,the leveling effect is good;when the speed is faster,the precision is poor and the flatness of the flat machine is smooth and the stability is poor.Over the years to try to adjust the feedback control algorithm and experience to improve the mechanical,hydraulic system structure effects are not obvious.In order to solve the problems encountered in the promotion of the graders,to improve the control system control precision and stability at the high speed of the graders,and to analysis of the grader system relationship between the output state variables and the input state variables with the parameters of the graders of the mechanism,and establishment of the grader model based on the multi-body dynamics.This paper analyzes the shortcomings of the design of the graders from the theory and experiment,and analyzes the main factors and minor factors influencing the shovel.Finally,the optimization design of paddy field graders.This study mainly carried out the following work:1)Numerical solution of mathematical model of simplified DAE(differential-algebraic equations)of grader.According to the principle of simplicity and simplification,the simplified model of the grader mechanics system is simplified and assumed from the structure.In this paper,we use Matlab's symbolic mathematical toolbox to automatically convert the original DAE mathematical model into a mathematic model that can becalculated directly by the Matlab solver to avoid the complicated process of complex modeling before modeling.2)Establishment of Rigid-Flexible Coupling Dynamics Model of Ground Mechanisms Based on Maplesim.Based on the analysis of the simplified mechanics model of paddy field,the shovel movement is affected by the parallel link deformation,and the parallel rod is used as the flexible body to establish the paddy field grader model.The use of computer-aided engineering(CAE)modeling to avoid direct dynamics modeling requires a higher limit on mechanics and mathematical knowledge.In this paper,we use Maplesim to establish a rigid-flexible coupled grader model,in which the parallel link is built with flexible beam elements in the multi-body library.3)The accuracy of the model is verified by high speed camera and AHRS experiment.1): In this paper,high-speed camera is used to calculate and analyze the centroid position and attitude of the groundwork shovel.The global coordinate system with the position of the gantry installation platform is established,and the component center of mass is the origin coordinate system.The image is processed by the image analysis software TEMA,and the 3D coordinates of the marker points in the global coordinate system are obtained.The 3D coordinates of the Euler angle and its core space are obtained by plotting the coordinates of the 3D coordinates in the local coordinate system according to the coordinate transformation relationship of the points in different coordinate systems.2): through the high-precision AHRS measured flat shovel mark point angle,angular velocity.Through the comparison of experimental results and model results,the accuracy of the model is verified.Based on the mechanical structure and working principle of paddy field graders,this paper establishes the multi-body dynamics model of paddy field graders.The model is validated by high-speed camera and high-precision AHRS.The mechanical structure of the grader is analyzed by using the model to find that the current mechanics of the grader is not enough and the main influencing factors are found.Through the optimization of the design of the paddy field grader(flat shovel optimization,hydraulic motor replacement leveling cylinder optimization),to prepare for the future grader control to improve the efficiency of paddy field graders.