# Analysis of Vibration Characteristics of the Grading Belt in Wolfberry Sorting Machines
## 1 Introduction  
In the realm of agricultural product processing, the grading of crops and fruits occupies a central role. With the rapid advancement of agricultural mechanization and intelligent technology, research and application of sorting equipment have emerged as critical areas for enhancing the added value of agricultural products and improving industrial competitiveness. In the field of agricultural sorting equipment, there are primarily four classification types based on their operational mechanisms: size sorters, weight sorters, color sorters, and intelligent sorters. [PERSON] [1] has developed an innovative roller nylon brush sorter that integrates both cleaning and grading functions. The roller sorting technology is more advanced compared to traditional mesh sorting equipment, significantly enhancing the adaptability for sorting irregularly shaped potatoes through flexible contact mechanisms. However, due to the relatively small particle size of freshwolfberries, the accuracy of grading remains comparatively low. The goji berry inertial screening machine, designed by [PERSON] [2], utilizes a crank-link mechanism to facilitate the reciprocating motion of the screen. When the acceleration of the screen meets specific criteria, the goji berry particles experience relative displacement. Particles that conform to the required size specifications are sorted through the openings in the screen. This method is exclusively applicable to dried goji berries. [PERSON] et al. [3] conducted a study on the automatic sorting technology for tomatoes utilizing machine vision, primarily focusing on the collection of color information and the detection of surface defects. [PERSON] [4] and [PERSON] [5] developed an efficient machine vision system designed for real-time detection and sorting of potatoes. However, this method is hindered by its low productivity and high operational costs. The grading of fresh wolfberries requires both a low damage rate and high accuracy in classification. Unfortunately, none of the previously mentioned research findings can be directly applied to the grading process for fresh wolfberries. In conjunction with the research findings of previous scholars, a novel sorting machine for fresh wolfberries (hereinafter referred to as the classifier) has been proposed for the purpose of particle size screening of fresh wolfberry granules. The operational principle involves conducting particle size classification of fresh wolfberries by regulating the gap size of the grading belt. The transmission mechanism plays a crucial role in influencing all aspects of the overall machine transmission and production processes. Various mechanical vibrations emerge from the differing operational states of the belt, which can directly impact both the stability of the grading belt's transmission and its grading accuracy. Taking into consideration the transmission structure and its dynamic processes within the classifier, a simulation of the flat belt transmission mechanism for classifying high-freshness wolfberries was conducted to ensure stability. Additionally, the sources of vibration were systematically summarized and analyzed. Flexible multibody dynamics (FMD) examines the motion characteristics of intricate mechanical systems, primarily focusing on the interplay between forces and deformations in systems composed of both rigid and flexible components throughout the motion process. In recent years, the study of flexible multibody dynamics has gained significant momentum, integrating computer simulations, multi-physical field coupling, and advanced control technologies.