An Improved Spatial Scheduling Algorithm for Sub-Assembly in Shipbuilding

The sub-assembly is the smallest combined unit of shipbuilding and the foundation stage of hull construction. The delay of the sub-assembly would make it difficult to carry out the subsequent construction task and even affect the on-time delivery of the ship. Improving the efficiency of sub-assembly welding and shortening the assembly cycle has become the key problem that needs to be solved urgently in shipbuilding. Sub-assembly scheduling problem needs to consider both temporal and spatial constraints, which is an NP-hard problem. In this paper, a spatial scheduling method is proposed for sub-assembly scheduling. To minimize the makespan, multiple spatial scheduling rules are integrated for sub-assembly spatial scheduling to avoid missing the optimal solution. Besides, the genetic algorithm is used to optimize the scheduling sequence and select spatial scheduling rule because of the NP-hard property of the problem. Finally, numerical experiments are carried out on different scale cases. Experimental results prove the effectiveness of the proposed method.