표면 근전도를 활용한 조립공정의 용접자세 영향요소 산출

Abstract

Welding, a key technology for assembling hull blocks in the shipbuilding industry, is mostly performed by hand owing to the complex structure and shape of production blocks. This manual welding requires various working postures depending on the shape and assembly sequence of the blocks being handled. Working posture has become a critical factor in determining the workload of a worker’s physical body. Based on the amount of workload applied, not only the worker's physical stability but also the man-hours required for the welding task are affected. Currently, major shipyards calculate the man-hours for welding by reflecting the welding factor, which is defined as the working time consumed in the welding process. A set of welding factors is known to be based on the accumulated experience in shipyards, whereas the verification or derivation process for these factors is not disclosed or available. This study proposes a method for quantitatively calculating work difficulty based on the working posture in a process where the posture acts as an important variable. Standard welding positions reflecting the actual welding work at shipyards were established by measuring and analyzing the working posture at the site. Surface electromyography (sEMG), a physiological evaluation method, was used to quantify the difficulty of the newly classified welding positions. The influence of muscle activity was determined by collecting and analyzing the EMG data of the welding positions. A work difficulty function based on the derived muscle activity is suggested to quantify the difficulty of each welding position based on the human factor. The validity of the proposed method was verified by comparing the results of shipyard welding factors and a musculoskeletal simulation package. The proposed work difficulty function based on physical activity can be readily applied to other fields in which workers' physical activities are involved.