TRADITIONAL AND TANDEM AGV SYSTEM LAYOUTS - A SIMULATION STUDY

The objective of this paper is to evaluate two common types of AGVS layouts: a traditional ''multiple vehicles'' layout and a tandem layout with single vehicle loops. Discrete event simulation models were developed in SIMAN to test various system design and operation parameters in the two layouts including number of vehicles needed, AGV speed, job assignment rule and job arrival distribution. In the simulation models, zone control methods were implemented to reduce AGV blocking, and several performance measures were collected for output analyses. Waller-Duncan Bayes Least Significant Difference (BLSD) tests were applied on the output to compare the two layouts and to identify parameters affecting the system performance. The results revealed that the traditional layout could produce a shorter job flow time and AGV waiting time in the stage area, while the tandem layout might perform better based on the number of jobs completed and vehicle blocking time. The difference in performance was significantly affected by the vehicle speed and the job arrival distribution.