A declarative approach to cyclic processes coupling and scheduling

Cyclic scheduling is an effective scheduling method in the repetitive discrete manufacturing environment where material-handling devices such as automated guided vehicles, robots and hoists are widely used to transfer parts between workstations in advanced manufacturing facilities. In this paper we address the problem of coupling cyclic material-handling tasks to produce a specified coordinated behavior. A new technique for modeling and performance evaluation of a loosely synchronized system composed of a set of cyclic processes interacting via shared and reusable resources is presented. Declarative model relating system desired behavior to its cooperating periodic component processes and an analytic model enabling to schedule coupled tasks is considered. Since our framework is iterative, properties and restrictions can be reviewed and refined as well. The analysis is illustrated using the example of a robotized flexible manufacturing system, where one of the main concerns is finding the structure of system such that an assumed steady cyclic state can be achieved.