In this study, an integrated bi-objective objective U-shaped assembly line balancing and parts feeding problem is explored by considering the heterogeneity inherent of workers. An optimization model is developed to formulate the addressed problem. Since the problem includes two different objectives, namely the minimizing the operational cost and maximum workload imbalance, the Pareto-optimal solutions are found by employing the second version of the augmented e-constrained (AUGMECON2) method. To investigate the impact of qualification of workers on the system performance, a set of scenarios is constructed based on the worker skill levels. Each scenario is determined based on the nature of the worker pool in which workers are assigned to the stations. The optimization model and implemented method are validated through data taken from water-meter and elevator producers. The computational results reveal that the scenarios have a great impact on system performance. In particular, it is revealed that as the skill levels of workers increases, the quality of the Pareto-optimal solutions increase by up to 30% in terms of the comparison metrics. Therefore, an order release mechanism and worker training activities are suggested to be performed to enhance system performance.

中文翻译：

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一个集成的双目标 U 形流水线平衡和零件进给问题：优化模型和精确求解方法

在这项研究中，通过考虑工人固有的异质性，探索了一个综合的双目标目标 U 形装配线平衡和零件供给问题。开发了一个优化模型来表述所解决的问题。由于该问题包括两个不同的目标，即最小化运营成本和最大工作负载不平衡，因此通过采用增强 e 约束 (AUGMECON2) 方法的第二个版本找到帕累托最优解。为了调查工人资格对系统性能的影响，基于工人技能水平构建了一组场景。每个场景都是根据将工作人员分配到工作站的工作人员池的性质来确定的。优化模型和实施方法通过来自水表和电梯生产商的数据进行验证。计算结果表明，场景对系统性能有很大影响。特别是，随着工人技能水平的提高，帕累托最优解的质量在比较指标方面提高了 30%。因此，建议执行订单发布机制和工人培训活动，以提高系统性能。