In this paper, a scheduling problem for multiple automated guided vehicles (AGVs) in a manufacturing
system is proposed and formulated. Considering the due date of AGVs requiring for material handling
among shops in a jobshop layout, their earliness and tardiness are significant in satisfying the expected
cycle time and from an economic view point. Earliness results in AGVs waiting and tardiness causes
temporary part storages in the shop floor. Therefore, we propose a mathematical program to minimize the
penalized earliness and tardiness. Since the mathematical program is difficult to solve with a conventional
method, an optimization method in two stages, namely searching the solution space and finding optimal
solutions are proposed. The performance of the proposed mathematical model is tested in a numerical
example and compared with several methods in the current literature.
