Towards the Leveling of Multi-Product Batch Production Flows. A Multimodal Networks Perspective

The problem studied in this paper is a cyclic job-shop problem with multiple Automated Guided Vehicles (AGVs). Job batches, which follow specific production routes, are processed, in the order of their operations, on multiple machines with standard processing times, and the fleet of AGVs perform the transportation operations of moving these job batches between the workstations. In this system, part sets of items are produced at fixed time intervals (takts). In the adopted model of the system, one can distinguish a layer of station-to-station transport, which is a network of local loops connecting subsets of workstations serviced cyclically by dedicated AGVs, and a layer of repetitive production flows which comprise job batches following a given set of production routes. The relationship between the elements of the structure of the system being modelled and its potential behavior is described by a system of integer equations. The resulting solutions enable the fast evaluation of production flow parameters including part sets, takt time, as well as repetitive-flow balancing aimed at maximization of the rate of system resource utilization. The high efficiency of the proposed approach, enabling the online prototyping of the production flow, is a consequence of omitting the time-consuming calculation of the sequencings of jobs within a cycle.