Petri net control using event observers and timing information

The use of an observer in Petri net control may significantly reduce the performance of the closed-loop system because of the incomplete knowledge of the net marking. In this pa-per we present an algorithm that uses the information on the timing structure associated to the net to improve the mark-ing estimate. This procedure may be invoked not only when the controlled system has entered a blocking condition (as in a previous work) but also whenever a transition has not fired for a time larger than its expected delay. The algo-rithm requires solving a number of integer linear program-ming problems and helps us to detect partial deadlocks and to accelerate the convergence of the marking estimation pro-cedure.