Collision Damage Test And Prediction Model Establishment Of Plug Seedling Based On Hanging Cup Transplanter

The widespread adoption of seedling transplanting technology has raised the standard for the transplanting proficiency of hanging cup transplanting machines.During the planting process,it is inevitable that the potted seedlings will collide with the transplanter,resulting in damage to the seedlings.This damage,in turn,increases the time it takes for the seedlings to recover after planting,thereby decreasing their quality and survival rate.This thesis employs a combination of theoretical analysis,experimental research,and discrete element simulation to investigate the impact damage,contact mechanics,and motion characteristics of potted seedlings during transplanting.The data set is established by soil trough transplanting test,and the artificial neural network method is used to predict the damage rate of pot seedlings under different parameters.The main conclusions are as follows:1.This thesis takes the water content of plug seedling substrate,seedling age and pot volume as the research object,and uses the orthogonal test method to test the pot damage rate,and obtains the combination of seedling process parameters with the smallest pot collision damage.At the same time,the Tekscan pressure distribution measurement system was used to measure and analyze the contact mechanical properties of the plug seedlings,and the relationship between the contact mechanical properties of the plug seedlings and the collision damage of the pot body was determined.2.The method of combining physical test with EDEM simulation test is used to calibrate the bonding parameters of the pot body simulation model.Through the puncture test,the maximum puncture force of the conical indenter on the pot body was obtained.Taking this as the response value,the optimal bonding parameter combination was determined by conducting three different tests,namely,the two-level factorial test,the steepest climbing test,and the Box-Behnken test.The resulting parameters were found to be the normal stiffness per unit area of 7.3×10~6 N/m~3,the normal stiffness per unit area of 6.775×10~6 N/m~3,the critical normal stress of 2600 Pa,the critical tangential stress of2600 Pa,and the bonding radius of 1.813 mm.3.EDEM software was used to simulate the transplanting falling process of pot seedling,and the motion characteristics,collision contact force and damage changes of pot seedling collision under different planting frequencies were analyzed from a microscopic perspective.The results show that when the planting frequency is different,the movement speed and posture of the pot seedling will change when it is transplanted and dropped,which will change the collision position and collision times between the pot seedling and the planting device.With increasing planting frequency,the pot damage rate tended to decrease and then increase.Using the soil trough transplanting test,the change trend of the damage of the plug seedlings under different planting frequencies was analyzed from a macro perspective,and the results were similar to the simulation test results.4.A BP neural network model with a hidden layer was established by using the size of seedling pot,substrate moisture content,seedling age and planting frequency as input and the damage rate of pot body as output.The outcomes demonstrate that the forecasted value for the test set is in close proximity to the measured value,with relative error rates ranging from 3.97%to 10.88%,and an average relative error rate of 6.50%.These results indicate that the BP neural network is highly feasible for simulating the damage rate of the pot body.