An Automaton Based Framework for Analysis and Control of Flexible Manufacturing Systems

Development and maintenance of control software has emerged as one of the most difficult problems associated with building Flexible Manufacturing Systems (FMS). FMS controllers , potentially the most flexible FMS components, are characterized by their inflexibility. To support configuration flexibility of FMS controllers, this work proposes a modular hierarchical control structure which combines multiple interacting models of the FMS. High resolution computational models which encode system state transition information are used for the lowest level of control. Given the FMS state, these models identify the set of enabled state transitions. At a higher level of abstraction, structural models which elucidate system structural characteristics are used to implement Structural Control Policies, SCP's,. These policies partition the set of enabled state transitions into feasible and infeasible transitions based on deadlock considerations. Issues in the development of SCP's include correctness, scalability, and optimality. Finally, performance models and control policies are used to optimize some set of system objectives over the set of feasible enabled state transitions. This paper discusses the fundamental aspects and presents some initial results in the theory of computational and structural systems modeling and control.