Fruit-flower-leaf dynamic response of Lycium barbarum L. for vibration harvesting

For the characteristic of infinite inflorescence, the aim of vibration harvesting of Lycium barbarum L. (L. barbarum) is to picking ripe fruits and leaving unripe fruits, flowers and leaves. Therefore, it is essential to understand the dynamic response of each component during vibration. In this study, the 3D models of a branch, ripe fruit, unripe fruit, flower and leaf were established respectively, which were assembled into a branch-fruit-flower-leaf system model based on the growth characteristics of L. barbarum. The vibration harvester was designed based on the hedge agronomy and simplified as rods, and a rigid-flexible coupling model was established using the kinetic analysis and the finite element method. The dynamic response of branch-fruit-flower-leaf during vibration harvesting was obtained when the rods continuously excited the branch. Results showed that the maximum acceleration of fruit-flower-leaf during vibration harvesting was in the same order of magnitude. And according to the formula of inertia force, the detachment force and mass were calculated and found that the detachment acceleration of ripe fruit was much smaller than that of unripe fruit, flower, and leaf. This study presents a theoretical basis for achieving the harvesting target. Scripts were written to simulate the vibration detachment process of ripe fruit, and high-speed photography was used for experimental verification. The results indicate that the simulation error was 9.15 %, demonstrating that the rigid-flexible coupling simulation is more effective. The field test showed that the picking rate of ripe fruit of 82.69 %, the picking rate of unripe fruit of 3.13 %, and the damage rate of ripe fruit of 4.06 %. The research provides a new analytical approach and theoretical basis for researching vibration harvesting.