Adaptive Petri Nets implementation. The execution time controller

Abstract

The reaction time of a controller is a fundamental matter in discrete event control systems. Petri nets are extensively used in this field. The controller reads the inputs, executes the control Petri net and writes the output in a cyclic manner. The reaction time of this controller depends on the Petri net structure, on the events sequence and on the algorithm that executes the net. With the objective of minimizing the reaction time, we decided to design a supervisor controller, which we have called execution time controller (ETC). The aim of the ETC is to determine in real time which algorithm executes the Petri net fastest and to change the execution algorithm when necessary. In the case of systems control, this minimizes the controller reaction time and also minimizes the power consumed by the controller. One possible application of the technique is the minimization of execution time of the programmable logic controllers programs developed in sequential function chart (SFC).