Agent-oriented Hybrid Scheduling System of Machines and Lots

A hybrid scheduling system of machines and lots was proposed. The system was composed of machine and lot scheduling systems which alternatively operate by an interval time during production. A machine agent corrects its own machine schedule when a process is behind schedule. The agent informs the schedule correction to the previous and next machine agents through peer-to-peer communication. The agents prepare for sending or receiving a lot according to the updated schedules. A lot agent collects its lot data from machine agents and composes the lot schedule. A scheduling management agent checks all of the lot and machine schedules and corrects them until any schedule problems disappear. The management agent then distributes the schedules to machine agents. In order to verify the feasibility of the system, computer simulation was done for scheduling of five machines which consisted of a reentrant process line, supposing that operation delay randomly occurred during production.