Solving the tandem AGV network design problem using tabu search: Cases of maximum workload and workload balance with fixed and non-fixed number of loops

A tandem AGV configuration connects all cells of a manufacturing area by means of non-overlapping, single-vehicle closed loops. Each loop has at least one additional P/D station, provided as an interface between adjacent loops. This study describes the development of three tabu search algorithms for the design of tandem AGV systems. The first algorithm was developed based on the basic definition of a tandem network. The second and third algorithms, consider no preset number of loops and try to evenly distribute workload among loops by using workload balance as their objective functions. They generate different design scenarios for the tandem network, which can be evaluated and selected using a multi-attribute objective function. The first algorithm and the partitioning algorithm presented by Bozer and Srinivasan are compared for randomly generated problems. Results show that for large-scale problems, the partitioning algorithm often leads to infeasible configurations with crossed loops in spite of its shorter running time. However, the newly developed algorithm avoids infeasible configurations and often yields better objective function values.