Out-Plant Milk-Run-Driven Mission Planning Subject to Dynamic Changes of Date and Place Delivery

We consider a dynamic vehicle routing problem in which a fleet of vehicles delivers ordered services or goods to spatially distributed customers while moving along separate milk-run routes over a given periodically repeating time horizon. Customer orders and the feasible time windows for the execution of those orders can be dynamically revealed over time. The problem essentially entails the rerouting of routes determined in the course of their proactive planning. Rerouting takes into account current order changes, while proactive route planning takes into account anticipated (previously assumed) changes in customer orders. Changes to planned orders may apply to both changes in the date of services provided and emerging notifications of additional customers. The considered problem is formulated as a constraint satisfaction problem using the ordered fuzzy number (OFN) formalism, which allows us to handle the fuzzy nature of the variables involved, e.g., the timeliness of the deliveries performed, through an algebraic approach. The computational results show that the proposed solution outperforms the commonly used computer simulation methods.