LAUSR

This paper addresses the design of observers for Discrete-Event Systems modelled by Output Petri nets. The observer is conceived as a copy of the system and a corrective term based on the execution trajectories. The observer performs a tracking of the transition sequence executed by the net. Based on this information, the observer is able to produce approximations of the initial and current state of the system. The focus is a subclass of Petri nets called S-Nets. A Lyapunov criterion is used for testing the stability of the herein proposed scheme. This criterion allows for proving that the observers are asymptotically stable and it supports characterizing the region of stability of the System/Observer pair, as well. An application example is developed through the paper to illustrate the results. Some graphs are provided to show the approximation error of the observer under different initial conditions.