Optimization of Practical Time-Dependent Vehicle Routing Problem by Ising Machines

The Vehicle Routing Problem (VRP) is an extension of the Travelling Salesperson Problem (TSP). A VRP determines the delivery sequence where multiple vehicles are available, delivery should be made to multiple points, and each point should be visited once. However, road conditions change depending on the time of day, and the time required to travel between two points changes accordingly. Unless these changes are considered, a calculated minimum cost is not realized in actual logistics. Aiming to apply the Time-Dependent Vehicle Routing Problem with Time Windows (TDVRPTW), which is a VRP extension that counts changes in the time required to travel between two points depending on the time of day, to Ising machines including quantum annealers, this paper proposes an effective formulation to realize TDVRPTW, composed of several objective functions and constraints. Further, this paper compares and evaluates the results obtained by a physical Ising machine and confirms the validity of the formulation, thus verifying the applicability of the TDVRPTW to quantum computing.