First, we need to understand the basic concepts and key issues in AGV scheduling, and then analyze the characteristics of existing scheduling methods.
The operation of an AGV alone is not complex. For example, when a machine tool needs to process a part, the higher-level MES control system sends a request to the AGV scheduling system, which then dispatches an AGV to transport the raw materials from the warehouse to the machine tool. This process can be called a job, which involves moving between a pair of work locations. In this example, the machine tool only provides a request ("What part do I want to process at what time?"). The scheduling system handles the selection of the AGV to transport the parts and raw materials and the route the AGV should follow.
Once the scheduling system specifies a path for the AGV, the onboard controller on the AGV performs specific motion control tasks according to the instructions, such as maintaining a certain speed and determining which wheels to use when turning at an intersection. Therefore, in a complete system, the AGV scheduling system sits between the upper-level and lower-level control systems, acting as a steward.
However, with multiple AGVs, scheduling becomes significantly more challenging, and the greater the number of AGVs, the greater the difficulty. Therefore, scheduling systems have become a key technology in the AGV industry. Practical AGV scheduling system software typically offers a wide range of features, including task management, vehicle status monitoring, route planning, map editing, and database queries.
First, we should be able to distinguish whether a problem is a scheduling problem or not. Suppose there's only one AGV operating in a factory. The scheduling problem degenerates into a simple route planning problem. This is because there's no need to consider which AGV to assign tasks to, nor does it require consideration of who goes first or who goes last at an intersection. Therefore, the scheduling problem presupposes that multiple AGVs share a route network. In other words, there's competition for resources among AGVs. Just like cars on the road, everyone wants to drive as fast as possible. If each driver only considers themselves and ignores others, the result is likely to be a jam where no one can move (congestion).
Consequently, individuals pursuing their own local optimal solution may end up with the worst-case scenario. Therefore, scheduling is necessary and sometimes crucial (traffic lights and traffic police both play a role in "scheduling").
With the diversification of market demands, production processes are becoming increasingly complex and dynamic. This often requires the simultaneous scheduling and planning of multiple AGVs to coordinate and complete handling tasks. The scheduling system plays a crucial role in executing this complex dispatching task. Leveraging a comprehensive and reliable scheduling system, businesses can truly achieve a "goods-to-person" intelligent warehousing operation model, empowering numerous enterprises to transform into "smart" manufacturing.