An heuristic for configuring a mixed uni/bidirectional flow path for an AGV system

Abstract

An heuristic methodology has been developed in the present work for configuring a mixed (hybrid) uni/bidirectional flow path for an AGV material handling system. The given unidirectional flow path layout, material flow intensities and vehicle travelling time matrix among various processing centres are taken as input information to this technique. A multiplicative function of material flow intensities between any two centres is used as a criterion for selectively configuring a path as a bidirectional one. The highest such product indicates that the shorter path between that pair of centres is a strong candidate for being configured as bidirectional. The heuristic has been applied to an illustrative FMS and various alternate flow path designs have been obtained. Simulation is then performed with the aim of comparing the productive potentials of the facility when it is operated on either unidirectional, or mixed uni/bidirectional, or allbidirectional flow path design alternatives. The benefits of bidirectional flows over unidirectional counterpart are significant in terms of system throughput rates and optimal AGV fleet sizes. However, traffic control becomes an important issue as vehicle interference and blocking increases with increase in bidirectionality in the network. The decision related to location and capacity planning of vehicle buffering zones is also addressed.