Ensayo de un modo de vibración en contrafase del sistema fruto-pedúnculo para la cosecha selectiva del café Test of a contraphase vibrating mode of the fruit-peduncle system for selective coffee harvesting

Coffee is characterized to present different maturation stages during harvest period, which confers a high grade of difficulty to the harvest mechanization task, being difficult to achieve a satisfactory level of selectivity (high content of maturelow content of inmature fruits within the harvested mass). Recent theoretical investigations carried out on the base of the mathematical modeling and CAD tool simulation of the coffee fruit-peduncle system, indicate that with the application of vibrational frequencies much higher to those historically used overseas (near of 20 Hz), can be expected an important qualitative jump in the selectivity levels during mechanized coffee harvesting. The research was carried out in a laboratory using an experimental vibrational unit able to simulate the desired effects, acchieving the excitation of isolates coffee branches (caturra variety) by shaking it in lateral and longitudinal direction, in a range of frequencies corresponding to a counter-phase vibrating mode of the fruit-peduncle system near to 200 Hz.. Content of immature fruits in the harvested mass oscillated between 3,8 and 5,15 % for the varieties Yellow and Red Caturra respectively, being obtained 100 % of detachment of mature cherries for both varieties.