Automated guided vehicle (AGV) systems complement the operation of flexible
manufacturing systems (FMS) by providing integrated automated material han
dling that capitalizes on the system's flexibility. Previous research consi
dering AGV systems for use in FMS installations has focused on complex cont
rol strategies to reduce the congestion problem often encountered in these
systems. Recently, attention has been given to tandem system configurations
that reduce congestion and simplify system control. The present study uses
the simulation methodology to compare the performance of three AGV configu
rations under a variety of experimental conditions. The results indicate th
at system size, load/unload time, and machine failure rate factors have sig
nificant impacts on the operation of the systems considered. In general, wi
th respect to due date performance, it is recommended to use the traditiona
l configuration in small systems while using the tandem/loop configuration
in larger systems. Furthermore, it is shown that the addition of the loop t
o the tandem configuration mitigates the sensitivity of the tandem configur
ation to the load/unload time factor as well as significantly improving its
performance under high load/unload times. Thus, if tandem configuration is
desired to reduce congestion and simplify system control, investments must
be made to directly reduce the load/unload times or to construct a loop to
avoid the load/unload time penalty.