Design and experimental evaluation of an orderly harvesting device for hydroponic leafy vegetables

Hydroponic leafy vegetables are well suited to standardized cultivation, but mechanical harvesting remains constrained by root entanglement, unstable clamping and disordered plant posture. To address these problems, an orderly harvesting device integrating rotating root flicking, clamping conveying and differential steering was designed and evaluated using hydroponic spinach and Shanghai bok choy. The device used counter-rotating nylon brushes for non-cutting root treatment, a twisted double-belt clamping conveyor for low-damage conveying and a differential belt steering unit for posture adjustment. Multi-level single-factor tests were conducted for brush speed, clamping-conveying twist angle and upper steering-belt speed. The root removal rate increased from 65.7% to 79.2% as brush speed increased from 600 to 1000 r/min, while the damage rate increased from 1.5% to 4.1%; 800 r/min was selected as a balanced condition, giving a root removal rate of 77.4% and a damage rate of 2.5%. Under a twist angle of 60^◦, a clamping gap of 24 mm, a conveying height difference of 200 mm and an upper steering-belt speed of 325 mm/s, spinach achieved a clamping-conveying success rate of 93.5%, a damage rate of 3.0% and a twist-angle MAE of 1.22^◦, while Shanghai bok choy achieved 89.0%, 4.0% and 1.94^◦, respectively. In differential steering, spinach achieved a steering success rate of 93.0%, a damage rate of 4.5% and an inclination-angle MAE of 1.15^◦, while Shanghai bok choy achieved 94.5%, 3.5% and 0.98^◦, respectively. The results indicate that the proposed device can complete coordinated root flicking, low-damage clamping conveying and posture steering for hydroponic leafy vegetables, providing a technical reference for orderly mechanical harvesting in controlled-environment production.