Synthesis and Implementation of Distributed Supervisory Control for Discrete Event Systems: Application to Automated Manufacturing Systems

Today's manufacturing systems (MS) require a high degree of flexibility and reconfigurability to survive in present markets characterized by frequent changes in demand and continuous evolution of products requirements. However, this beget a big complexity in the tasks of analysis, control, and optimization, which makes the use of formal methods a necessity for the study of MS. In this work, dynamic MS are abstracted as Discrete Event Systems (DES). Supervisory Control Theory is a formal method widely used to design control of DES. However, for large scale systems, this method confronts the problems of the state space explosion, understanding the generated models, and updating these in case of redesigns. To raise these challenges, we propose a formal approach to distributed control synthesis and implementation for automated MS. The proposed approach lies in the separation among local synthesis and global synthesis. The plant is modeled in a local modular fashion using finite state machines and the desired constraints are specified as logical Boolean equations. Synthesis algorithms taking into account the different semantics of these models are developed. A formal verification methodology using Model-checking is integrated to the approach to verify the absence of blockings, safety, and liveliness of the obtained distributed control. For implementation purposes, the approach proposes a method to interpret the distributed control into Grafcet (IEC Standard 60848, 2013), which is a standard widely used in manufacturing to specify the functional behavior of control systems. An experimental automated MS illustrates the approach.

Yassine Qamsane received the M.Sc. and the Ph.D. degrees in electrical engineering with the focus on automation and control technology from the Cadi Ayyad University of Marrakech, Morocco, in 2012 and 2018, respectively. He is currently a postdoctoral research fellow with the department of Mechanical Engineering at the University of Michigan, Ann Arbor. His research interests include modeling, control, diagnosis, verification and validation of modular/distributed discrete-event systems with the focus on automated manufacturing systems. His current main research interest is smart manufacturing. Dr. Qamsane received the Third International Afro-European Conference for Industrial Advancement (AECIA) Best Paper Award in 2016.