NSGA-II for solving a multi-objective, sustainable and flexible job shop scheduling problem

Recently, sustainable scheduling has emerged to make the
trade-off between economic, environmental and social factors. While classical scheduling research focuses on economic and environmental indicators such as makespan and energy consumption, modern human-centred manufacturing systems consider additional important factors such as workers’ well-being and ergonomic risks. This study proposes a multi-objective mathematical model that jointly optimizes the makespan, the total energy consumption, and the OCRA (Occupational Repetitive Actions) index (a measure of ergonomic risk) in the case of a flexible job shop. The model has the originality of also taking into account the travel times of operators and products between machines. We use the NSGA-II
method to solve it. The first results allow us to analyze the mutual influences of the criteria and demonstrate the advantage of such a method to obtain a good compromise between the three objectives in a reasonable resolution time.