Scheduling a pick and place packaging line

In this paper, we introduce the Pick and Place Packaging Problem (P4), for optimally scheduling a packaging system with one input conveyor (pick) and one output conveyor (place). We give a formal definition of the underlying dynamic optimization problem. We describe two properties that hold for its solutions and present an efficient row generation approach exploiting these properties. Starting from a basic version of the problem, we introduce two variants where we account for the possibility of holding the grip of items and variable conveyor speed. We extend the proposed exact solution method to these two cases. Then, we present an efficient Iterated Local Search heuristic for the problem and its variants. Numerical results show the effectiveness of our approach.