COFFEE HARVESTING I: DETERMINATION OF THE NATURAL FREQUENCIES OF THE FRUIT STEM SYSTEM IN COFFEE TREES

As part of a study of mechanized harvesting of coffee by vibration, an investigation of the natural frequencies ofthe fruit stem in coffee trees was undertaken. Theoretical models of one and two degrees of freedom were used to estimatethe natural frequencies. Results obtained with these models indicate that frequencies of resonance for ripe cherries (redcherries) and halfripe ( pinton ) are lower than the value obtained for green cherries. For ripe cherries in the first vibrationmode, the frequency of resonance ranges from 1450 to 1500 c.p.m while in the second mode of vibration the frequency ofresonance is above 28,000 c.p.m.