Búsqueda de modos de vibración apropiados para la cosecha selectiva del café.

Coffee harvesting with the aid of mechanical means becomes impracticable for the immense majority of coffee producers in the world, due fundamentally to that, in general, in the moment of the crop, the plants contain fruits in all their maturation status and have not been able to be developed machines that guarantee a selective detachment of the cherries during harvest operation. In a first study (Symposio do Café do Brasil. EMBRAPA), a modal analysis of coffee fruit-stem system was made. Starting from this analysis, the possibility of achieving the selective detachment of the fruits (removing of a high percent of mature fruits and low percent of immature ones) can be expected if the vibrating frequencies of the machines that use this work principle, are selected in the surrounding of a vibration mode "in contrafase" of the fruit-pedicelo-peduncle system. In this first study, an analysis of the first twelve vibration modes of different configurations of the fruit-pedicelo-peduncle system of coffee, was carried out. This study resulted enough for the analysis of configurations with one fruit for peduncle, but it was insufficient for an analysis of the behavior of configurations with two or three fruits for peduncle. In this paper an study of 25 vibration modes of fruit-pedicelo-peduncle system of coffee (coffea arabica) varieties "Red Caturra" and "Yellow Caturra" is presented. As a result of the study four variants of counter-phase vibrating mode of the fruit-pedicelo-peduncle system were founded, being able to recommend the more promissory mode for selective harvest of coffee. [ABSTRACT FROM AUTHOR]