Spatial Scheduling Optimization Algorithm for Block Assembly in Shipbuilding

Block assembly consumes the majority of processing time and resources in shipbuilding, and the block spatial scheduling (BSS) related to block assembly has been widely studied as the key to improve shipbuilding efficiency. BSS is a complicated NP-hard problem that aims to minimize the makespan. Since each block has specific building time and space constraints, the BSS problem can be hardly found with an acceptable solution by using constant scheduling rules. Thus, in this study, we considered the BSS problem as a time-constrained 3D bin packing mathematical model and proposed an allocation algorithm, best contact algorithm (BCA), that is more suitable for dynamic processes. Then, for global optimization of the BSS problem, we regarded the starting time of each block as a variable and used the genetic algorithm (GA) to operate and optimize the block assembly sequence. Finally, we tested the BCA + GA scheduling system with real data from a shipyard and thereby determined the block scheduling status and the daily utilization rate of the work plate. Comparison shows that the proposed algorithm is able to get shorter makespan and better block scheduling effect; it realized the optimization of the block spatial scheduling dynamically.