Modal Analysis and Experiment of a Lycium barbarum L. Shrub for Efficient Vibration Harvesting of Fruit

Abstract

The most common harvesting method of Lycium barbarum L. (L. barbarum) is manual harvesting, resulting in low efficiency and high cost. Meanwhile, the efficiency of vibration harvesting, which is considered an efficient mechanical harvesting method, can be significantly improved if the optimized resonance frequency of the shrub can be obtained. To vibration harvest fruit efficiently, a 3D model of the shrub was established based on measurements of the shape parameters, and material mechanics models of the branches were established based on physical tests. The modal analysis of the shrub based on finite element method (FEM) simulation was performed to obtain the range of resonance frequency, and the modal experiment of the shrub using acceleration sensors and an impact hammer was conducted to obtain the accurate resonance frequency. Based on the results of the modal analysis and experiment, the optimized resonance frequency was determined to be 2 Hz. The field experiment showed that the fruit fell off when the branches were vibrated at this frequency. The results provide the design basis for the efficient vibration harvesting of L. barbarum.

Development, integration, and field evaluation of an autonomous citrus‐harvesting robot

“…The huge potential of the automated harvesting industry offers significant opportunities for the research and development of fruit‐harvesting robots. The vibration method is mostly used to harvest the fruits as the raw material for secondary processing (Castro‐García et al, 2012; Savary et al, 2011; Zhao et al, 2021). However, such an approach often damages fruit and is unsuitable for precise harvesting.…”

Analysis on Dynamics Characteristics of Vibratory Harvesting for Cutted Sea buckthorn branch and Design of mechanism parame

“…Therefore, the vibration mechanism of the research object can be simulated and studied, thus providing a theoretical basis for the design parameters of the excitation mode and the vibration de-vice. L. Phillips et al [12] proposed using the finite element analysis method to carry out dynamic simulation analysis of the trunk and side branches of fruit trees, Jian Zhao et al [13] used ABAQUS software to analyze the modal harmonic response of the Lycium barbarum shrub and found that the optimal excitation frequency was 2 Hz. Wang Dong et al [14] established three typical fruit tree models, the natural frequencies and modal shapes are obtained by using the finite element method.…”

Optimization of Vibration Parameters for Red Jujube Trees with Different Diameters

“…To enhance the efficiency of vibratory harvesting, it is necessary to study the fruit vibration mechanism. Zhao et al [14] used physical tests to establish a three-dimensional model of a shrub and a material mechanics model of its branches. They conducted a modal analysis of the shrub using the finite element method and modal experiments with acceleration sensors and impact hammers to determine the optimized resonant frequency of 2 Hz.…”

“…Fu et al [22] simplified the jujube "branch-stalk-fruit" system as a double pendulum vibration model to analyze natural frequencies and obtain the natural vibration frequencies of the system (14.69 Hz and 17.26 Hz). Constant-frequency vibration tests were conducted on jujube tree samples at various amplitudes (3 mm, 5 mm, and 7 mm) and frequencies (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24) to investigate the effects of vibration frequency and amplitude on the instantaneous acceleration of each branch. DHDAS analysis showed a correlation between vibration frequency and instantaneous acceleration, while amplitude did not have a significant effect.…”