Morphology-Informed Mechanical Design and Preliminary Evaluation of an Integrated Machine for Continuous Lettuce Postharvest Processing

Abstract

The scientific problem addressed in this study is how a continuous mechanical architecture can maintain stable lettuce handling while improving treatment-medium access to irregular, overlapping leaf surfaces. We formulate this problem as a morphology-informed design and evaluation task. The proposed machine integrates soil removal, a reserved vision-based yellow-leaf detection and root-trimming station, multi-angle disinfection, water–air washing, combined airflow drying, film wrapping, weighing, and boxing modules on a chain-conveyor platform with bowl-shaped fixtures. The evaluation follows a design-to-evidence workflow: lettuce morphology and process requirements are mapped to module geometry; chain, lead-screw, gear, and motor parameters are checked analytically; an application-oriented geometric spray-coverage model tests fixed versus swinging bilateral nozzles; static finite element analysis screens the frame under defined design loads; and prototype assembly verifies spatial compatibility. The covered-surface proxy increased from 7.24% for fixed bilateral spraying to 13.58% for a ±35° swinging case under explicit screening assumptions, while the frame analysis gave 0.0224 mm maximum deformation and 7.30 MPa maximum von Mises stress. These outputs support a preliminary, mechanically feasible platform and a testable explanation for why adjustable spray orientation may improve access to complex lettuce surfaces. They do not constitute measured cleaning, microbial, trimming, drying, packaging, throughput, or reliability performance.