Object-oriented design of a modular scheduling architecture

The importance of finite-capacity schedulers is increasing, with respect to the widespread MRP packages, due to their ability to model the shop floor more accurately. However, this very advantage may turn into a disadvantage, since it is quite difficult to devise a high-quality general purpose scheduler able to cope with the technological peculiarities of different production environments. Furthermore, a detailed schedule is prone to disruptions due to the uncertainty affecting the shop floor. Hence, we need both a modular approach to devise and assemble local schedulers and a way to link predictive and real time scheduling. To cope with both requirements, we propose a scheduling approach based on a generalization of the well-known shifting bottleneck method. The scheme is based on the coordination of local schedulers by a general scheme, such that the knowledge needed to cope with technological peculiarities is locally confined. The aim of the coordination mechanism is to generate a set of local due dates which can be used as targets to drive real time dispatching.