Design and Implementation of Supervisory Control for an Electropneumatic Station Subject to Faults in Material Flow

Human intervention in automated manufacturing systems may result in faults in material flow leading to incoherent behavior of the control system. Particularly when multiple workpieces can be operated concurrently, the design of a programmable logic controller (PLC) that can handle such nondeterministic events is a complex task that justifies the use of formal methods such as the Supervisory Control Theory (SCT). The main objective of this work is the use of SCT for the systematic design of the automation system of an electro-pneumatic station of a Modular Production System prone to faults in the material flow. A code generation tool has been used to translate the modular supervisors into an IEC61131 PLC program, whose automata-based structure has been exploited by several functionalities of a SCADA System. The implementation of supervisory control allows the station to flexibly process five workpieces simultaneously, with conformance to functional requirements and with safety to deal with the nondeterministic removal of workpieces along the station.