State and firing sequence estimation of Petri Net application to: Manufacturing sysems

In this paper we address both problem of discrete state and firing sequences estimation for Discrete Event Systems (DES) modeled by Petri nets(PN). We present a new and simple method to construct an Unknown Input observer for DES modeled by PN by using traditional methods for descriptor systems. The proposed observer is designed in order to estimate both the marking places and the firing vector of transitions and it guarantee exponential convergence of the state estimation error to zero. Sufficient conditions for the existence of the observer are also given. A simple manufacturing systems will be considered as an illustrative example to show the effectiveness of the proposed approach.