Design and Proof-of-Concept Evaluation of a Passive Lower-Limb Exoskeleton for Citrus Harvesting Tasks

Citrus harvesting involves repetitive lower-limb and postural activities that expose workers to elevated risks of work-related musculoskeletal disorders (WMSDs), particularly affecting the lower back and lower limbs. Passive lower-limb exoskeletons offer a potential low-complexity solution, which does not drastically change the current harvesting process, to mitigate these physical demands; however, their feasibility for agricultural applications remains insufficiently explored. This study presents the design and laboratory-based proof-of-concept evaluation of a prototype passive lower-limb exoskeleton intended to assist citrus harvesting tasks. The proposed system incorporates a mechanical load redistribution frame with passive elastic elements to support hip and knee joint movements during harvesting postures without requiring external power or active control. The design was informed mainly by literature, local industry consultation, and simplified biomechanical modeling approaches. The prototype’s feasibility was assessed under controlled laboratory conditions using simulated harvesting squat motions across a range of loading conditions. Preliminary observations indicate a reduction in musculoskeletal demand during supported tasks compared to conventional load-carrying conditions, suggesting that the proposed mechanism can partially offload effort of lower-limb muscles. Overall, this work presents a proof-of-concept prototype and feasibility assessment, offering preliminary baseline indications under single-subject laboratory conditions rather than generalizable evidence for passive lower-limb exoskeletons in harvesting activities.