Mathematical modelling for process design of walking worker assembly line in productivity and ergonomics perspectives

High worker-hour productivity and improving ergonomics conditions are major concerns of industry, especially in human-centred production systems (e.g. manual assembly systems). From the view of some manufacturing managers, converting fixed worker assembly line to walking worker assembly line (WWAL) involves opportunities and pitfalls for both mentioned aspects. This view point is supported by the complaint, i.e. no modelling research that can help them to develop their own capacity in the design of WWAL considering both productivity and ergonomics. This paper proposes a mathematical model that can be used by designers, manufacturers and dealers for the effective design of WWAL that significantly affects the productivity and ergonomics performance measures. Different combinations of process design parameters are compared with several alternative scenarios of WWAL design using well-planned numerical experiments. Graphical analyses were carried out to examine the relationships between design parameters (factors) and performance measures. The model can support WWAL practices in two ways: firstly, it can improve the understanding of how such systems behave and what factors drive performance. Secondly, it can help to determine what types of policies for successful operation of this system can quickly and economically be selected in light of the different levels of production demand.