A method for the synchronisation of networked discrete-event systems

This paper describes networked discrete-event systems as a set of controlled subsystems, which are physically and digitally connected. The controlled subsystems have two operation modes: In the autonomous mode they achieve local tasks independently of each other, whereas in the synchronisation mode they perform given tasks synchronously by using communication. The paper proposes to model the networked discrete-event system by an Input/Ouput (I/O) automata network and gives a method for partial cooperation between the controlled subsystems. A tracking control architecture, which has been previously published for centralized systems, is extended to cope with the physical interconnections and the digital communications with other controllers. It is proved that the resulting networked tracking controller guarantees autonomous and partially cooperative behaviour. These results are demonstrated by means of an example featuring a flexible manufacturing system.