System approach to a generic software specification for flexible manufacturing system job flow management

Programmable automation is a key factor to fully exploit the potentiality of flexible manufacturing systems (FMS). In particular, the flexibility of the control software acting at the operational level, allows one to make the control activities easier to program and re-program. This characteristic needs a generic software able to control an arbitrary FMS producing an arbitrary part-mix, according to arbitrary control strategies. Turning attention to the operational job flow management, a typical FMS is modelled as a discrete-event dynamic system in a formal and unambiguous way. The system state and its transitions (i.e. logical and physical entities, their attributes and relationships and the mechanism ruling their modifications in time) are described. The discrete-event model allows one to point out the organization of a generic software for job flow management, in terms of its inputs, outputs, knowledge base and decision-making processes.