Unit load size selection problem of AGV in multi-assembly line production system with unequal cycle times

Abstract

This thesis deals with the problem of determining unit load size of automated guided vehicle(AGV) in multi-assembly line production system. It is assumed that an AGV delivers assembly parts to each workstation of assembly lines from a miniload automated storage/retrieval system(AS/RS) and conveyor lines transport subassemblies between workstations. In this system, determination of unit load size of parts carried by the AGV becomes an important decision factor due to its effects on the work-in -process inventory level and the operating cost of the system. With the assumption of equal unit load size for each workstation, three types of AGV operating policies are studied. Then the assumption is relaxed to permit different unit load size among assembly lines. For each policy, a nonlinear mathematical model is formulated. Based on the characteristics of the objective function and feasible region, a solution algorithm is developed. To illustrate the models, problems are chosen and solved.