Research on bilateral assembly line optimization for man–robot collaboration based on multi-objective migration bird optimization algorithm

Purpose With the successive German “Industry 4.0” strategies proposed, many collaborative robots are being used in manufacturing. The man–robot collaborative assembly model is now widely used in bilateral assembly lines. The purpose of this study is to systematically investigate the problem of balancing the man–robot collaborative bilateral assembly line by considering the workload to reduce the workload and increase productivity. Design/methodology/approach Based on optimizing the beat and cost, focusing on the balance of working time and load between stations, introducing a comprehensive smoothing index optimization objective and considering constraints such as the number of employees, robots and workload thresholds, a balanced multi-objective planning model of a man–robot serial collaborative bilateral assembly line with consideration of workload is established. Findings The bilateral assembly line balancing problem was solved using man–robot collaboration. The production smoothing index was optimized from 508.65 to 105.68, and the cycle time was optimized from 1,737 to 1,067, resulting in a 38.6% increase in productivity. Originality/value This study optimizes man–robot allocation and extends the bilateral assembly equilibrium model by optimizing the personnel load and the integrated smoothing index.