A Robust Formulation for U-shaped Assembly Line Balancing Problem Under Task Time Uncertainty by Considering Worker Skills

The U-shaped assembly line balancing (UALB) problem has been extensively investigated in the existing academic literature. However, only a limited number of studies consider the uncertainty in the assembly lines. In this research, a robust formulation is developed for the addressed problem under task time uncertainty by focusing on the heterogeneity inherent of workers. The worker resources are not the same in terms of either skills or skill levels. Therefore, it is plausible to investigate the manufacturing system from this perspective to provide managerial insights regarding the performance metrics, such as the total cost, number of stations. Besides, the uncertainty of processes in a manufacturing system must be considered to improve system performance. Since robust optimization is a powerful technique to overcome uncertainty, the robust approach is employed in this study. First, the nominal model for the UALB problem is presented and followed by that the robust counterpart of this model is provided. The optimal results are obtained for different parameter levels after solving the model. The analysis of the results is made through real data provided by a water-meter assembly line.