The effect of joint forces and torques on speed variation in automobile assembly lines

BACKGROUND: In production industries, physical loads have been observed for employees. The impact of these loads has been investigated in automotive industry assembly lines. OBJECTIVE: The purpose of this study was to evaluate the effects of different takt times on the forces and torques in body joints during loading. METHODS: Data were collected using an integrated system, including a motion capture system as a hardware subsystem and a tool for physics-based human simulation as a software subsystem. RESULTS: The results were compared for a human working for 3 seconds and 5 seconds; for 3 seconds, there was a negative impact on the bottom of the torso (L4), top of the torso (T12), left shoulder and upper arm (Lshoulder) joint forces and torques, but there was a reduction in the joint forces and torques on the right shoulder and upper arm (Rshoulder). Furthermore, the results reveal fluctuations and peak values in all joint forces and torques at the initial intervals due to the variation in speed. CONCLUSIONS: The initial acceleration is highly correlated with the risk of musculoskeletal disorders, physical loads and ergonomic problems. This study illustrates the importance of providing appropriate processing times for operators.