Finite Element Modeling And Robust Control Of Spray Rod Rigid Frame Of Plant Protection Machine

With the development of science and technology,the protection of crops has gradually been a higher priority in agriclture production.To prevent the crop from being affected by diseases,insects,grasses and rats during their growth,the plant protection machinery is used and it playes a very important role in also promoting and regulating growth of plants to ensure the food harvest and effective supply of agricultural products.Over the years,chemical control method has been the major method to prevent the pests and diseases of plants in agricultural production.Researches at home and abroad have found that when the sprayer is working in the field,the vibration of the sprayer boom will be caused by the ground excitation of the spary machinery,which will affect the uniformity and efficiency of the spray.Therefore,it necessary to control the vibartion,and establishing a model for the elastic boom and suppressing the elastic shape caused by the boom vibration are very useful way to improve the uniformity of the spray and the work efficiency of spary.In order to study and suppress the elastic deformation of the spray boom,In this thesis corresponding research work has been carried out.In this thesis,the research status of plant protection machinery at home and abroad is summarized,and the shortcomings in the research of plant protection machine boom is analysed.The boom structure considered in this thesis is selected and it is 24 m long,and then it is divided into 27 nodes.The finite element method is used to establish its model,and the kinematics model of the boom is established.The spray boom is discretized,and the displacement of each node is analyzed by a dividing unit to obtain a displacement interpolation function.The appropriate transformation matrix is selected to establish the overall generalized coordinate array,and all the units are connected to establish the kinematic equations of the whole boom.According to the established kinematics model of the boom,a comprehensive theoretical analysis of the boom vibration is carried out.On the basis of theoretical analysis,the analysis of the boom is carried out by using the software ANSYS.Based on the analysis of ANSYS,under the initial disturbance,the vibration of the boom was simulated by MATLAB,and the corresponding response diagrams of the nodes in all directions were obtained.By comparing the displacement images of each node,it is found thatthe degree of deformation of nodes 1,and node 14 are the largest or the second largest,and so the displacement of these nodes are chosed as the basis for judging the control effect.According to the actual operation of the spray boom of plant protection machine,in the process of control design,the augmented state equation of the system is established,and then three robust controllers are designed to restrain the vibration in horizontal and vertical directions respectively.In the simulation of closed-loop system the nodes 5,10 and nodes 6,9are selected as position to exert control respectively.It is verified that the control performance of the robust controllers have expected result.And when the controller is added at nodes 5,10,the control performance is better.