Iterative Widen Heuristic Beam Search Algorithm for Scheduling Problem of Flexible Assembly Systems

Scheduling of assembly manufacturing systems has received much attention in recent years, but the scheduling problem of deadlock-prone flexible assembly systems (FASs) is rarely studied. Based on the Petri net models of FASs, this article studies the scheduling problem of deadlock-prone FASs, and the heuristic beam search (HBS) algorithm is proposed to minimize the makespan. In HBS, the state space of the FAS is searched level by level, and two types of evaluation functions are proposed to ensure that only the most promising states are explored. To find a better solution in an acceptable time, the HBS algorithm is integrated with the iterative policy, and the iterative widen heuristic beam search (IWHBS) algorithm is obtained. Experimental and comparison results validate the effectiveness and superiority of the IWHBS algorithm over other heuristic search algorithms.