Optimization for system operation and analysis of automated guided vehicle systems in flexible manufacturing systems

Abstract

and (iii) it is the first study to simulate FMS using AGV systems and model the loss of system throughput through a queueing network model.

(ii) It has developed a practical cluster control algorithm and demonstrates superior performance compared to existing commercial algorithms

however, there has yet to be much research, so decisions are made based on experience and intuition at the industrial sites.

This paper first describes the industry-university collaborative projects conducted during the degree program for the operation of a cluster control system for AGVs. Based on this, the study defines the typical characteristics of the operational problems in AGV systems. It, then, proposes a generalized algorithm to minimize the total delivery time within the entire system considering the mutual interference between vehicles. The proposed algorithm determines the optimal vehicle resource allocation, the optimal route of the vehicles, and the optimal battery charging station and battery charging level of the vehicles for the entire system. Moreover, the study compares the proposed algorithm with existing commercial methods under various conditions through simulation and verifies its superiority by applying it to plants operating dozens of AGVs. Finally, this paper provides rule-based insights that industrial sites can easily apply through the solutions provided by the proposed algorithm.

This study proposes a queueing network model that simulates FMS with AGV systems. The model allows us to analyze the impact of AGV systems on the production capacity of plants and to prove that even with increasing system input, the production capacity of a plant may decrease due to bottlenecks in the AGV systems. Additionally, the study identifies a sufficient condition that leads to reduced production and provides another sufficient condition for maintaining the maximum capacity of plants in FMS through numerical experiments.

This study has contributed as follows: (i) It is the first study to analyze AGV systems using a mathematical approach

This dissertation addresses an operational problem for automated guided vehicle (AGV) systems in flexible manufacturing systems (FMS) and analyzes the impact of AGV systems on plant production capacity.

Many industrial sites operate AGVs for delivery within plants. These vehicles use batteries as their power source, and the batteries used during the transport process are charged or replaced by the predetermined rules at battery charging stations. Temporary congestion is a common issue in these systems due to the operational limitations of battery charging stations. Moreover, frequent inter-vehicle interference, resulting from the growth of the number of vehicles and complicated transport routes, aggravates severe congestion. These restrictions result in transport delays within the production process and can cause the AGV systems to act as a bottleneck for the entire production environment. Therefore, the cluster control system for AGVs is essential