Combinatorial scheduler: simulation and optimization algorithm

Describes a novel job shop scheduler based on a heuristic optimization algorithm and discrete event simulation. One of the features of this scheduler is high-speed scheduling, which depends on the configuration of this system. The optimization algorithm determines the product sequence to be used in the shop. Then, a simulator determines each product flow based on the shop floor model and simple dispatching rules. The key point for high-speed scheduling is to reduce the complexity of simulation rules. The simulator has responsibility only for local optimization. A second feature of this scheduler is the scheduling algorithm which can handle multiobjectives. In a real factory, the due date has top priority for scheduling, but the lead time and machine utilization can be changed by production circumstances. In this scheduler, machine load leveling is used for shortening the lead time, and a higher load at a later process is used for increasing the machine utilization. An operator can assign the balance of lead time and machine utilization by setting a parameter. An application to a real shop floor is discussed