A survey of dynamic scheduling in manufacturing systems

The problem of scheduling is concerned with searching for optimal (or near-optimal) schedules subject to a number of constraints. A variety of approaches have been developed to solve the problem of scheduling. However, many of these approaches are often impractical in dynamic real-world environments where there are complex constraints and a vari ety of unexpected disruptions. In most real-world environments, scheduling is an ongoing reactive process where the pr esence of real-time information continually forces reconsideration and revision of pre-established sche dules. Scheduling research has largely ignored this problem, focusing instead on optimisation of static sc hedules. This paper outlines the limitations of static approaches to scheduling in the presence of real-time in formation and presents a number of issues that have come up in recent years on dynamic scheduling. The paper defines the problem of dynamic scheduling and provides a review of the state of the art of currently developing research on dynamic scheduling. The principles of several dynamic scheduling techniques, namely, dispatching rules, heuristics, me ta-heuristics, artificial intelligence techniques, and multi-agent systems are described in detail, followed by a discussion and comparison of their potential.