Dispatching rail-guided vehicles and scheduling jobs in a flexible manufacturing system

The objective of this paper is to develop and evaluate dispatching strategies of rail-guided vehicles (RGVs) in the load/unload area of a flexible manufacturing system (FMS) with a bi-directional track. Our focus is on the load/unload area of the system, but the effective combination of RGV dispatching and scheduling rules to prioritize jobs in the buffer storage between the load/unload area and the machine centre is also explored. Five RGV dispatching rules are developed and evaluated along with the common scheduling rules using computer simulation. The statistical analyses based on the simulation show that the RGV dispatching rules with priority given to parts outperformed the other dispatching rules in throughput and part flow time. The scheduling rules may or may not significantly affect the system performance, depending on the characteristics of the job queue. The result on RGV dispatching reveals the need to efficiently dispatch the material handling vehicle despite its simple structure and straight routing.