Synthesis of No-Wait Cyclic Schedules for Cascade-Like Systems of Repetitive Processes with Fixed Periods

Abstract

The paper deals with the problem of synthesis of cyclic schedules for cascade-like topology repetitive systems that share resources using the mutual exclusion rule. Such processes are represented by, for example, repetitive transport tasks occurring in AGV systems, in which the carriages share sectors of routes belonging to neighboring manufacturing cells or cyclic operations carried out in urban transport systems such as train, subway, in which individual lines use shared hubs (i.e. inter-change stations, cross-platforms, etc.) combining mesh-like communication networks. In this context, the problem in question concerns determining the operation times of cascade-like repetitive processes and their start times, which guarantee the existence of a no-wait cyclic schedule of processes. An extended variant of the cascade-like system is considered, in which, in comparison to the classical “chain” model with two operations carried out as part of the process, each cyclic component process contains additional operations. The purpose of this work is to provide necessary and sufficient conditions for process operations and their start times to ensure that there is a cyclic schedule free of waiting for resources, and then apply the developed conditions in the synthesis procedure of the cascade-like system parameters.