Deadlock-free scheduling for timed Petri net models combined with MPC and backtracking

Abstract

This paper proposes algorithms that incrementally compute control sequences driving the marking of timed Petri nets from an initial value to a reference one, avoiding forbidden and dangerous states with a duration that approaches the minimal value. The proposed algorithms are applicable to a large class of discrete event systems in particular in the domain of flexible manufacturing, communication and computer science or transportation and traffic. To overcome the most burdensome part of the computations, only the sequences encoded in a small area of the reachability graph are worked out. The main contributions are to propose an estimation of the minimal duration of the remaining sequences to the reference based on the computation of the firing count vectors and a progressive search of the forbidden and dangerous states according to a backtracking phase. The approach is suitable for deadlock-free scheduling problems.