Models for AGVs’ Scheduling and Routing

An automated guided vehicle (AGV) is a driverless material handling system used for horizontal movement of materials. AGVs were introduced in 1955 (Muller, 1983). The use of AGVs has grown enormously since their introduction. The number of areas of application and variation in types has increased significantly. AGVs can be used in inside and outside environments, such as manufacturing, distribution, transshipment and (external) transportation areas. At manufacturing areas, AGVs are used to transport all types of materials related to the manufacturing process. According to Gotting (2000) over 20,000 AGVs were used in industrial applications. The author states that the usage of AGVs will pay off for environments with repeating transportation patterns. Examples of these environments are distribution, transshipment and transportation systems. Warehouses and cross docking centers are examples of distribution areas. AGVs are used in these areas for the internal transport of, for example, pallets between the various departments, such as receiving, storage, sorting and shipment areas. At transshipment systems, such as container terminals, AGVs take care of the transport of products between the various modes of transport. Gotting (2000) presented an overview of available technology for automation in container terminals. Furthermore, navigation and vehicle guidance systems applicable in various indoor/outdoor environments are described. Haefner and Bieschke (1998) stated that AGV systems can provide benefits to both the port and its customers by executing transportation requests between vessels and inland transportation.