Optimization Framework for Assembly Line Design Problem with Ergonomics Consideration in Fuzzy Environment

This paper presents a framework for solving assembly line design problems by considering ergonomics aspects. Although ergonomics factors have been ignored in conventional optimization problems in this area, in the long term, ergonomics risks and work-related injuries can impose considerable expenses on production systems. Moreover, in the design stage, different types of uncertainty in operational and ergonomics aspects can affect the optimization model. Therefore, the optimization framework in this study includes the results of ergonomics assessment tools and employs fuzzy logic to tackle imprecise factors. In the context of our problem, the sources of imprecision are twofold: environmental uncertainty and system uncertainty. Environmental uncertainty is related to demand uncertainty derived from market variations and customers’ behavior. System uncertainty includes the uncertainties within the production process that partially relate to human aspects, such as uncertainty in task execution time and the physical capacity of the operators.