Optimization of ergonomic parameters in overhead arc welding using grey relational analysis

Overhead arc welding tasks are physically demanding, often leading to work-related musculoskeletal disorders (WMSDs), particularly affecting the upper limb and lower back due to sustained awkward postures, repetitive motion, inadequate workstation design, and prolonged standing. These factors affect the worker's performance, health, safety, and comfort. This study aimed to optimize the shoulder angle, elbow angle, and wrist position to minimize discomfort and shoulder pain, grip force, and task time in overhead arc welding tasks. An L27 orthogonal array design was used to evaluate the effects of shoulder angles, elbow angles, and wrist positions on grip force, task time, discomfort rating, and shoulder pain. Grey relational analysis (GRA) identified the optimal factor combination, while ANOVA applied on Grey Relational Grades (GRG) identified the significance of each input factor. To validate the GRA results, TOPSIS was applied, followed by experimental confirmation of responses at the optimal settings. The GRA identified shoulder angle (115-125°), elbow angle (30-40°), and neutral wrist position (A₂B₃C₂) as the optimal configuration. ANOVA results revealed that shoulder angle, elbow angle, and wrist position significantly influence grip force, task efficiency, shoulder pain, and discomfort levels. This study examines ergonomic factors in overhead arc welding to minimize WMSDs and improve productivity and comfort. It offers insights into the optimal shoulder, elbow, and wrist positions but is limited by a controlled environment and limited-angle ranges. Future research should involve varied participant profiles, explore grip force at different points, capture EMG signals, and evaluate torch movement consistency.