Design and Experiment of a Posture Adjustment and Differential Steering Device for Orderly Harvesting of Hydroponic Leafy Vegetables

Hydroponic leafy vegetables have high yields, but their mechanized harvesting level is low. To improve the quality of orderly harvesting of hydroponic leafy vegetables, an ordered harvesting device with functions such as root flicking, posture adjustment and differential steering has been designed. A root-flicking method using rotating brushes was proposed, and experiments analyzed the effect of brush rotation direction. A posture adjustment method using a twisting conveyor belt was proposed, and experiments analyzed the impact of different twist angles on the stability of the adjustment process and the posture angle. A differential steering method using two pairs of conveyor belts with differential speeds was proposed, and experiments analyzed the impact of different steering belt speeds on steering stability and actual inclination angle. The root-flicking experiment results for hydroponic leafy vegetables showed that the counterclockwise followed by clockwise brush rotation combination performed better, with a root removal rate of 74.9%. The posture adjustment experiments on hydroponic leafy vegetables showed that the optimal twist angle for clamped and twisted conveyance was 35°, and the Mean Absolute Error (MAE) between the twist angle and hydroponic leafy vegetables posture angle was 0.38°. The differential steering experiment results indicated that the preferable belt speed difference for the directional conveyance of hydroponic leafy vegetables was 75 mm/s, and the MAE between the theoretical and actual inclination angles was 0.96°. Validation experiments based on posture adjustment and differential steering tests demonstrated a continuous harvesting success rate of 87.5%. This study provides valuable references for the design and development of orderly harvesting equipment for hydroponic leafy vegetables.