Simulation Analysis Of Dynamic Characteristics Of Rice Canopy And Optimum Design Of Applicator

China is the largest rice production and consumption country in the world.To ensure the stability of rice planting area and rice output is very important to the food security of China and even the world.But in the whole growth cycle of rice,there are many kinds of diseases and insect pests,and the parts of them are not the same.At present,several commonly used plant protection methods in the later stage of rice growth,i.e.after the rice canopy is sealed,the droplets of medicine liquid are intercepted by the upper canopy,which is difficult to reach the lower and middle canopy,resulting in the poor control effect of rice planthopper,sheath blight and other diseases in the lower and middle canopy,which has a great impact on the yield.Therefore,it is of great significance to optimize the design of plant protection machinery and to solve the problems of difficult application and poor application effect in the middle and lower part of rice canopy by adopting a reasonable way of application.In this paper,on the basis of relevant research at home and abroad,starting with the biomechanical characteristics of rice plants,the mechanical parameters(elastic modulus)of rice plants are studied,and the simulation model of rice plants is established by combining the physical parameters(moisture content,outer diameter,wall thickness,etc.)of rice plants.On the ANSYS Workbench platform,explicit dynamics simulation was carried out to study the dynamic characteristics of rice plant under the condition of putting a mechanical putter component on the common sprayer sprayer,and the feasibility of the simulation was verified by high-speed photography.Then,the effects of height,speed and material of push rod on the displacement of rice canopy were studied by simulation,which provided a solid theoretical basis for the design optimization of rice plant protection machinery and the setting of field operation parameters.The specific work of this paper is as follows:(1)The determination of rice mechanical parameters is mainly the elastic modulus of rice stem.In order to establish the dynamic model of rice plant in the process of mechanical flat push crown gap application,this paper uses SMS physical property analyzer to carry out three-point bending test on the treated rice straw samples.The test factors are loading rate,water content and gauge distance,to explore their influence on the test results,and finally determine the mechanical property parameters of rice straw.(2)The rice plant model was established and the explicit dynamics simulation was carried out.The measurement of rice plant characteristic parameters including height,leaf number,leaf distribution,leaf area and so on was completed,and the model was established on the modeling software.Combined with the measured mechanical characteristic parameters,the dynamic simulation was carried out jointly with the push rod.Through the high-speed photography experiment,the correctness of rice plant model and simulation method was verified,the error reason was analyzed and the model and simulation parameters were modified.Based on the modified model,the relationship between the action effect of mechanical push rod and the forward speed,the height of push rod and the material of push rod is studied by simulation,and the optimal scheme is obtained.(3)Design and optimization of the pusher system of the auxiliary machinery of the pesticide applicator.According to the application requirements,the design of push rod support can realize the adjustment of height direction and relative position of push rod and spray rod in horizontal direction;the optimization design of material and structure of push rod can further reduce the possibility of mechanical damage of rice plant and meet the rigidity requirements of operation function while realizing the crown opening function;the construction of push rod control system is completed Set the height of push rod before operation and automatically compensate the height change of push rod during operation.(4)Field performance test of crown gap applicator with mechanical flat push.Through the actual droplet deposition test,the relationship between the relative position of the putter and the spray rod and the droplet deposition effect is analyzed,and compared with the spraying effect of the common spray rod sprayer,and the feasibility of the mechanical push crown gap spraying method is verified.