Selective Separation Mechanism and Picking Parameter Optimization of a Flexible Roller-Brush for Osmanthus fragrans at Full Bloom Stage

To overcome the high labor intensity and severe vegetative damage inherent in the mechanized picking of Osmanthus fragrans at the full bloom stage, a selective separation mechanism utilizing a flexible roller-brush was proposed. First, biomechanical thresholds for selective detachment were quantitatively established, requiring 1.2 N for corolla-pedicel abscission and >5.0 N for petiole-branch retention. Rigid-flexible coupled transient dynamic simulations verified that flexible polyurethane (PU) bristles effectively attenuate impact forces via a "flexible unloading effect." This mechanism precisely transfers targeted detachment kinetic energy (~1.3 N) to fragile pedicels while restricting forces on robust petioles (~2.5 N) below the damage threshold. Furthermore, a terrain-adaptive picker (CZD-01) with a three-degree-of-freedom contour-following arm was developed. A mixed I-Optimal response surface design was employed to optimize the operational parameters. ANOVA revealed that bristle material is the absolute dominant factor determining the leaf detachment rate (P<0.0001). Under the globally optimized configuration-a roller brush rotational speed of 161 r/min, a circumferential rotation speed of 8 r/min, and smooth PU bristles-field validations demonstrated an average flower picking rate of 84.0% and a strictly controlled leaf detachment rate of 6.5%. The developed flexible picking technology achieves an optimal balance between productivity and canopy protection, offering a robust mechanization paradigm for fragile floral crops.