Design of a portable hand-guided harvester for mature scallions to reduce damage and avoid debris inclusion

Abstract The aim of this study was to address the problems of physical damage and soil contamination associated with the traditional scallion harvesting process by designing a portable hand-guided harvester and evaluating it through field experiments. The drawbacks of the traditional manual harvesting method were studied and analysed, with the aim of achieving efficient and low-loss harvesting of scallions through mechanical means, and reducing the breakage rate and soil content. The stability of scallions during the harvesting process and the reduction of damage are ensured by adopting a single-row one-time hand-guided mode of harvesting operation, which includes the four core steps of loosening soil, conveying the plants, removing debris, and collecting the plants. Several key components are designed, such as a support feeding device, a clamping conveying device, and a soil screening and debris removal device. This research involved indoor simulation conveying tests and field performance tests. The results indicate that the proposed scallion harvester meets all expected performance metrics, with a miss rate of 3.03%, a qualified debris removal rate of 96.08%, a qualified conveying rate of 96.98%, a damage rate of 3.65%, and a total loss rate of 6.67%. Furthermore, its operational efficiency is significantly higher than that of manual harvesting, as it substantially reduces labour costs and improves the overall productivity of scallion harvesting. Statics and computational modal analyses of the frame structure show that it can meet the strength requirements of normal working conditions, while avoiding the phenomenon of resonance and ensuring the stability and reliability of the harvester. The single-row hand-guided scallion harvester described in this study has good scope for application and practical value, and represents an efficient, low-loss solution for the mechanised harvesting of scallions. Particularly in large areas of planting, it can effectively alleviate the problem of labour shortage and promote the transition towards mechanisation of the scallion industry.