Optimization of Timed Petri Nets using CP-SAT

Paper in proceeding, 2024

An optimization formulation is presented for timed Petri nets, based on a recently developed optimization solver where a satisfiability solver is integrated with constraint programming. The solver, called CP-SAT, is a part of Google's OR-Tools. The first optimization formulation includes an arbitrary number of concurrent sequences of operations, with shared, alternative, and local resources. A benchmark shows how much faster CP-SAT is compared to both an alternative SAT optimization solver and an A∗implementation. The optimization formulation is then generalized to mixed alternative and concurrent sequences. A comparison with a recent MILP formulation for timed Petri nets is presented, showing the strength of the proposed optimization formulation. Finally, an evaluation of an industrial-sized flexible manufacturing system, including uncontrollable events, demonstrates how efficient and easy to implement the proposed strategy is compared to existing results.