University of Michigan

Euisu Park

Pramod P Khargonekar

Dawn M Tilbury

Method and system for creating a control-flow structure which represents control logic for use in a manufacturing system based on the system's timing bar chart are described. A modular representation of the control logic is described. In the setting of a high volume transfer line, each station of the line is considered as a module and a simple method to generate a Petri net representation from the timing bar chart is described. Modified reduction rule and locality property are applied to compose the logic of a Petri net module. Using the well known properties of the marked graph which is one of the subclasses of Petri nets, the qualitative characteristics of the logic controller of the system such as liveness, boundedness (safeness) and recoverability can be verified. A live and safe marked graph can be directly transformed into Grafcet (which is one of the EC 1131-3 languages) and, using this Grafcet representation, a logic controller can be implemented directly. The reconfigurability properties of this approach to implementation of logic controllers is also described.

Method and system for creating a control-flow structure which represents control logic, reconfigurable logic controller having the control logic, method for designing the controller and method for changing its control logic

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Ann Arbor, MI, United States of America

Euisu Park