Deadlock-free scheduling in automated manufacturing systems with multiple resource requests

This paper addresses the scheduling problem of a class of automated manufacturing systems with multiple resource requests. Each operation may need more than one resource type and multiple identical units with the same resource type. The scheduling problem is formulated by timed Petri nets model under which the scheduling goal consists in sequencing the transition firing sequence in order to avoid the deadlock situation and to minimize the makespan. In the proposed genetic algorithm with deadlock-free constraint, a deadlock detection method based on D-siphon technology is addressed to reschedule the sequence of transitions. The enabled transitions should be fired as early as possible and thus the quality of solutions can be improved. In the fitness computation procedure, a penalty item for the infeasible solution is involved to prevent the search process from converging to the infeasible solutions. The method proposed in this paper can get a feasible scheduling strategy as well as enable the system to achieve good performance. Numerical results presented in the paper show the efficiency of the proposed algorithm.