Taming Heterogeneity and Complexity of Embedded Control

The On-line Diagnosis of Time Petri Nets Based on Partial Orders

 

G. Jiroveanu¹ – B. De Schutter² – R.K. Boel¹

¹ EESA - SYSTeMS Research Group Ghent University Technologiepark 914 Zwijnaarde 9052, Belgium {george.jiroveanu,rene.boel}@ugent.be

² Delft Center for Systems and Control (DCSC) Delft University of Technology Mekelweg 2, 2628 CD Delft The Netherlands {b.deschutter}@tudelft.nl

ABSTRACT. In this paper we propose an on-line diagnosis algorithm for Time Petri Nets (TPN). The plant observation is given by a subset of transitions and the faults are modeled by a subset of unobservable transitions. The plant behavior is derived on-line and the diagnosis is obtained checking whether or not some or all of the traces in the behaviour that obey the plant observation contain fault events. We calculate the legal plant behavior as a set of configurations in the net unfolding. We calculate the set of legal traces in the TPN deriving for each configuration the solution set of a system of (max, +)-linear inequalities called the characteristic system of the configuration. We present two methods to derive the entire set of solutions of a characteristic system: the first method is based on Extended Linear Complementarity Problem while the second method is based on constraint propagation.

KEYWORDS: discrete events systems, partial orders, on-line monitoring

1. Introduction

This paper provides a survey of recent work on the on-line diagnosis of Time Petri Nets (TPNs) based on partial orders. ...