Finite Element Modeling And Deformation Control Of Large Plant Protection Machine Boom Rigid Frame

With the development of agricultural technology,traditional agricultural production methods have gradually been replaced by modern agricultural production methods.In the current agricultural production,chemical control has become an important way for plant protection and promotion of production.The application of large-scale plant protection machinery has increased the efficiency of spraying pesticides in the process of plant protection.The machinery’s reliability,high efficiency,and safety have been recognized by the industry.However,due to the complex operating environment of the farmland,the vibration and balance effects of the boom system have become the key factors in the uniformity of spray distribution.When a large-scale boom sprayer is operating in the field,the pitch,roll,and yaw of the boom cause by the complex conditions of the field may cause the boom to vibrate and deviate from the optimal application position.Due to the enlargement of the boom sprayer,the vibration will also cause the boom to deform elastically.This greatly affects the sprayer’s spray quality,such as over spray,leakage spray,and even bring the severe vibration and deformation can even make the spray bar scratch the crops,resulting in serious losses.In this thesis,the rigid frame structure boom used in the large plant protection machine boom is considered,and the elastic deformation of the boom frame structure is taken into account.The 24 m long boom rigid frame structure was divided into 27 nodes,and a model was established using the finite element method.According to the different vibration conditions,the vertical and horizontal vibrations of the rigid frame were considered separately to reduce the number of degrees of freedom in modeling and improve the calculation efficiency.After the model had been established,the free vibration analysis of the rigid frame in this frequency range was carried out according to the vibration frequency range(vertical direction 0-10 Hz,horizontal direction 0-3Hz)generated by the disturbance of the boom in the field.At the same time,the amplitude of each node was found through the modal vibration diagram,and the validity of control was determined by 1,14 nodes.For the elastic deformation caused by the vibration generated in field operations of the plant protection machine,the linear quadratic optimal control method was used in this paper.The controller was designed for the vertical vibration model of the plant protection machine boom rigid frame.For different applied control force positions,a series of simulation were performed to verify the effectiveness of the controller.Then the modal control method,which is more affixed to the engineering,was used to transform the horizontal vibration model of the sprayer boom rigid frame into a modal space.The modalities in the corresponding frequency range were controlled to verify and the effectiveness of the control method was presented.