Design and testing of a bionic flexible low-damage tobacco-leaf harvesting mechanism

ABSTRACT Addressing the agronomic requirements of a high harvesting rate and a low breakage rate in mechanical tobacco-leaf harvesting, this study, rooted in biomimetic approaches, analyzed the kinematic patterns and force application characteristics of human fingers during the manual harvesting process. Based on this analysis, a novel mechanical harvesting mechanism was proposed, featuring a chain-wheel system equipped with flexible harvesting fingers. The mechanism fundamentally replicates the manual harvesting action, thereby achieving efficient and low-damage mechanical harvesting of tobacco leaves. Then, based on the theory of stem-leaf connection in tobacco plants and the contact force model between the harvesting fingers and the main vein of the tobacco leaf, a series of simulation experiments were designed to ascertain the viability of the proposed harvesting mechanism and to analyze the influence of operational parameters on the harvesting rate and breakage rate of tobacco leaves. The optimal operational parameters were identified, with the feeding speed ranging from 0.5 to 0.7 m s-1 and the installation angle between 30° and 40°. Finally, the field trials, conducted in accordance with these optimized parameters, yielded a tobacco leaf harvesting rate of 96.72% and a breakage rate of 13.63%. These outcomes not only significantly enhance the harvesting rate but also substantially reduce the breakage rate of tobacco leaves, thereby fulfilling the agronomic requirements for mechanical tobacco-leaf harvesting. This study has thus provided a fundamental basis for the key harvesting components of tobacco-leaf harvesting machinery.