Caracterização dinâmica da planta do cafeeiro visando a colheita mecanizada por vibrações mecânicas

Abstract

The coffee mechanized harvesting has been carried out efficiently by using the mechanical vibrations theory, being affected by factors related to the machine and the plant, making it necessary to know its modal properties. In this context, this work was developed with the aim of characterizing the dynamic behavior of coffee plants in order to determine their modal properties in the field conditions, considering fruits at different maturation stages, mature and immature beans. For this, the instrumentation of fifteen plants chosen at random was carried out, for the collection of field data evaluating different scenarios. From experimental modal analysis tests, it was possible to observe that there was a higher incidence of natural frequency peaks concentrating between 20 and 40 Hz. The values of the damping ratios of plagiotropic branches of coffee plants with predominantly mature fruits, relative to the upper, middle and lower parts, were 0.145, 0.134 and 0.127, respectively. Through the induction of mechanical vibrations, it was possible to determine the values of vibration transmissibility of coffee plants, in which the frequency of 20 Hz presented greater vibration transmissibility in relation to the other induced frequencies. Finally, from frequency range tests it was possible to evaluate the dynamic behavior of coffee plants, which showed that there was a higher incidence of natural frequency peaks concentrated above 40 Hz. From this study, it was observed that the selective harvesting of coffee fruits using the exclusive application of vibration becomes unfeasible, since there were no significant differences for the fruits at different stages of maturation and also due to the overlapping of values of frequencies observed in the studied frequency range.