A Unified PSO-based method for multi-hoist scheduling in advanced Galvanic plants

In this work, we propose a method based on the unified particle swarm optimization (UPSO) for no-wait multi-hoist scheduling, including a collision avoidance heuristic. Conflicts due to track sharing between hoists and no-wait constraints represent major issues to be addressed. Consequently, a complex optimization problem has to be solved dynamically, to identify the best operating strategy to be executed depending on the characteristics of the current job list. A decomposition procedure has been developed to speed up the solution of the large-scale optimization problem at hand. The proposed approach is demonstrated on a real galvanic process layout, showing the improved performances achieved by the proposed heuristic compared to the monolithic approach.