A simulation of AGV dispatching rules for supplying parts to assembly lines

Abstract

The just-in-time philosophy has been widely applied in production, especially when supplying parts to assembly lines. To supply parts, and to ensure the parts are fed to assembly units in time, automated transportation systems, such as the AGV system are used because they are widely considered to be an efficient transportation method. However, there are some problems which occur while using this system. Most problems come from an inappropriate AGV launching scheme, which can lead to vehicle jams and cause vehicles to wait to load parts. As a result, AGV cycle time is increased. Most AGV systems use heuristic dispatching rules to control vehicle movement. However, there is no particular dispatching rule suitable for all cases. In this research we propose heuristic dispatching rules based on transportation time balanced for specific layout of an automotive assembly line environment with multiple vehicles. Heuristic dispatching rules, including the number of AGVs launching, were used to decrease cycle times to meet time constraints. Simulation modelling of automotive industry assembly lines is developed in ARENA. The results from the simulation experiments are analysed using multivariate variance analysis to determine the effects of dispatching rule factors based on transportation times.