VIBRATION TRANSMISSIBILITY OF THE COFFEE FRUIT-PEDUNCLE SYSTEM: A FORCED VIBRATION STUDY OF HIGH FREQUENCY AIMING MECHANICAL HARVESTING

ABSTRACT Semi-mechanized and mechanized harvesting use machines that promote the transference of vibrational energy and impact to achieve the detachment of coffee fruits. The aim of this study was to evaluate the vibration transmissibility in coffee fruit-peduncle systems, using high-speed cameras, submitted to high frequency harmonic excitation in different combinations between frequency and amplitude of vibration, identifying working ranges suitable to perform selective harvesting. Vibration transmissibility was determined for the coffee fruit-peduncle systems, for the maturation stages unripe and ripe that were subjected to a sinusoidal harmonic displacement, in which the input parameters were frequency (35, 45 and 55 Hz) and peak-to-peak amplitude (3.5, 5.0 and 6.5 mm). An experiment was used to study the effect of frequency and amplitude on vibration transmissibility in a completely randomized design in a factorial scheme 3 x 3 x 2, with three replications. The frequency of 35 Hz, associated with the amplitudes 3.5-6.5 mm, was the one that most influenced the results of vibration transmissibility. For the frequency of 55 Hz and amplitude of 6.5 mm, in the ripe maturation stage, the vibration transmissibility was higher than 1.0, which could be a suitable combination for selective coffee harvesting.

摘要
半机械化与机械化咖啡采收设备通过传递振动能量与冲击力，实现咖啡果实的脱落作业。本研究旨在评估咖啡果实-果柄系统（coffee fruit-peduncle systems）的振动传递特性（vibration transmissibility）：采用高速相机（high-speed cameras）对经高频谐波激励的该系统开展测试，激励参数涵盖振动频率与幅值的不同组合，旨在筛选适配选择性采收的作业工况范围。本研究针对未成熟与成熟两个成熟度阶段的咖啡果实-果柄系统，施加正弦谐波位移激励，激励输入参数为振动频率（35、45、55 Hz）与峰峰值幅值（3.5、5.0、6.5 mm），并测定其振动传递特性。实验采用3×3×2析因设计的完全随机方案，设置3次重复，探究振动频率与幅值对振动传递特性的影响。研究结果显示，当振动频率为35 Hz、幅值处于3.5~6.5 mm区间时，对振动传递特性的影响最为显著。在成熟果实阶段，当振动频率为55 Hz、幅值为6.5 mm时，系统振动传递比大于1.0，该参数组合可作为咖啡选择性采收的适配工况。