Collaborative Assembly Line Design: a bi-objective model for minimizing costs and energy consumption

In Industry 5.0, new manufacturing systems, commonly known as hybrid manufacturing systems, are designed by combining humans and automated technologies in shared workspaces. By adopting these systems, the benefits of both humans and automation can be achieved, ensuring flexibility and adaptability. In such a context, the technological advancement of collaborative robots has guided the transition from robotic or semi-automated assembly systems to collaborative assembly systems. The selection and balancing phase of the equipment tools are crucial to these new assembly systems. In a workplace where workers and collaborative robots collaborate, they guarantee minimal investment costs, efficiency, worker safety, and limited energy consumption. This paper focuses on Collaborative Assembly Lines (CAL) and aims to optimally solve a bi-objective model that minimizes the assembly system's total costs and energy consumption. In assessing energy consumption, one considers the variation in energy expenditure when collaborative robots are either engaged in work or idle, operating at a fixed speed. Furthermore, collaborative robots and workers can execute their tasks by adopting three strategies: independent, sequential, and supportive. The model is optimally solved for a numerical case by applying the ϵ-constraint algorithm. Finally, some managerial insights are derived from the numerical case.