DEM-based parameter optimization and tests of digging green onions

In view of the problems of easy damage and high digging resistance in the process of green onion harvesting, a mechanical model of digging green onions was established by taking the moment of digging and drawing green onions as the research object, and the main factors affecting the digging and harvesting effect were determined as the angle of digging, the dip angle of clamping carrier and the length of shovel. Thus, a complex simulation model of soil-green onion-digging mechanism system reflecting the state of harvesting was established, and the model was verified by testing soil compactness. The simulation tests were carried out by means of the complex simulation model of soil-green onion-digging mechanism system, making it clear that digging angle and the length of shovel have a extremely significant impact on the digging resistance, and the dip angle of the clamping carrier had a significant impact on the digging resistance. Through target optimization, the optimal combination of digging parameters was obtained, namely, the digging angle of 20°, the dip angle of clamping carrier of 25° and the shovel length of 70 mm, with the digging resistance of 1394 N at this moment. The field digging resistance test has showed that the average digging resistance is 1543 N with the average clamping damage rate of 1.27% and the average clamping loss rate of 0.44%, which can meet the requirements of green onion harvesting.