Proactive/reactive approach for maintenance tasks in time critical systems

The maintenance of systems involved in production processes must be carried out with maximum efficiency and minimum downtime, especially on time-critical systems (operation times are included between a minimum and a maximum value). This paper presents a proactive/reactive control to fit preventive maintenance into a busy production schedule. As preventive maintenance is regarded as a non-preemptive task, p-time Petri net is used as modelling tool to generate temporal and logical constraints to be considered. To update the tasks scheduling, flexibility on time and on task order is obtained by permitting negative instants in the used firing instant approach. The illustration of the method is made on a graphite ceramic cell