Pallet location and job scheduling in a Twin-Robot system

This paper introduces the Twin-Robot Pallet Assignment and Scheduling Problem (TRPASP) in which two robots operating on a rail must be scheduled to pick up and deliver a set of products. The objective is to minimise the makespan, defined as the time taken for the robots to transfer all products from their pickup locations to their delivery locations, and return to their starting positions. Pickup locations are known a priori, while delivery locations must be assigned to minimise the makespan. The robots must respect a safety distance to avoid collisions. The paper presents a mathematical model for the TRPASP before introducing four heuristic algorithms for solving the problem. Computational experiments demonstrate that the best results are returned by a parallel hybrid metaheuristic.