Design and experiment of an automatic seedling pick-up device for strawberry transplanter

Mechanized strawberry transplanting is essential for improving operational efficiency and reducing seedling damage. To address these challenges, this study designed an automatic seedling pick-up device specifically for strawberry transplanters. Firstly, a novel clamp-type picking claw was developed based on the mechanical characteristics analysis of strawberry seedlings extracted from the tray. Based on the operational principles of whole-row seedling extraction, equidistant separation, and precise placement, the structure and working mechanism of the picking-and-placing device were designed. Secondly, a dynamic model of the picking claw was established for kinematic analysis based on coupled EDEM-RecurDyn simulation. The strawberry seedling picking process was conducted to investigate the effects of needle spacing, picking acceleration, and insertion depth on the integrity ratio of the plug seedlings. Finally, an orthogonal experimental design was employed, integrating single-factor tests, analysis of variance, response surface methodology, and multi-objective optimization. The results showed that the optimal seedling picking parameters were picking acceleration of 0.26 m/s², claw spacing of 37 mm, and insertion depth of 85 mm. With these parameters, field validation experiments demonstrated a relative error of 4.29% between the measured and predicted plug seedling integrity ratio, which confirmed the reliability of the optimized parameters. This research significantly contributes to improving plug seedling integrity during mechanical transplanting and enhances the efficiency and effectiveness of strawberry transplantation.