A new flexible multi-AGVs scheduling model with pre-waiting time in an intelligent manufacturing system

This paper studies a flexible flow-shop scheduling problem with limited resources (FFSP-LR) which is based on an actual air-conditioning production line in an intelligent manufacturing system. It extends the classical flexible flow-shop scheduling problem by considering practical constraints of the number of the AGVs (automated guided vehicles) on the transportation resources. The problem aims to determine the optimal scheduling results that minimizes the idle waiting time and pick-up waiting time of the workstations. To solve this problem, a pre-waiting scheduling model (PWSM) is proposed by taking into account the advance waiting time of AGVs. The experimental results show that the proposed PWSM is able to reduce idle waiting time and pick-up waiting time up to 425.01 and 414.25 comparing to traditional FCFS (First Come First Serve) strategy respectively. Correspondingly, these two types of time could be saved up to 87.01% and 98.57%. Finally, the overall efficiency of the intelligent manufacturing system is improved since the PWSM is able to effectively reduce the idle waiting time and pick-up waiting time of the workstations under the condition of limited transportation resources.