Determination of unit load sizes of AGV in multi-product multi-line assembly production systems

This study deals with the problem of determining unit load sizes of automated guided vehicles (AGVs) in multi-product and multi-line assembly production systems. It is assumed that an AGV delivers assembly parts to each workstation of assembly lines from a miniload automated storag/retrieval system (AS/RS), and conveyor lines transport subassemblies between workstations. In this system, determination of the unit load sizes 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. Under a proposed AGV dispatching policy, a nonlinear mathematical model which allows unequal unit load sizes among assembly lines is formulated. Based on the characteristics of the objective function and feasible regions, a heuristic solution algorithm is developed. To illustrate the model, problems are chosen and solved.