摘要：AbstractThis paper is about the incremental computation of control sequences for timed discrete events in uncertain environments. The considered uncertainties are the occurrences of uncontrollable events. The domains of application include but are not restricted to flexible manufacturing, communication, computer science, transportation and traffic. Timed Petri nets that include uncontrollable transitions and behave under earliest firing policy are used for modeling purpose. Unexpected firings of the uncontrollable transitions are considered and result in a risk to deviate from the scheduled trajectories. The aim of the controller is to drive the marking of the net from an initial value to a reference one, in minimal time and risk. For this purpose, a cost function is proposed that includes an evaluation of the risk. This function is used with a beam search approach that prunes the expansion of the reachability graph and computes feasible sequences in the most promising subparts of this graph. Robust scheduling is obtained as a consequence.
关键词：KeywordsDiscrete event systemstimed Petri netsuncontrollable eventsscheduling problemsmanufacturing systems
