A Puzzle-Based Sequencing System for Logistics Items

The new demands of the current market including for space should be satisfied by designing modern material flow systems. Designing warehouses using effective material handling equipment significantly supports cost reduction and efficient space utilization. Sequencing of items is an important process that leads to enhanced logistics operations. Current approaches are not capable of fully fulfilling dynamic changes. Methods: In this paper, a puzzle-based sequencing system with a high density and highly efficient floor space utilization was successfully developed. Accordingly, two solving methods were investigated: game tree and pathfinding algorithms. A-star was chosen based on pathfinding algorithms in order to find the shortest solution of the puzzle in which the sequencing time was decreased. The pre-sorting strategy was proposed to overcome the unsolvable configuration issue that cannot be solved by the aforementioned methods. Moreover, the shape of the puzzle was considered. Results: Based on numerical calculations, we found that a square shape was better than a rectangle in terms of solution steps, and we confirmed the direct relationship between the aspect ratio and rectilinear distance, which directly affects the pre-sorting steps. Conclusion: Our results prove that the puzzle-based sequencing system should be highly preferred for effective floor space utilization compared to the current systems

物流倉庫のためのパズルベースソーティングシステムに関する研究

The new challenging demands of the current market including space should be satisfied by designing modern material flow systems, with higher levels of flexibility and reliability. Designing warehouses using effective material handling equipment such as multi-directional conveyors significantly reduces the cost towards efficient space utilization and time-saving. Several storage strategies can be applied depending on service concerns and products storage conditions, for instance, for storing frozen items that need specific temperature conditions, the zoning strategy is applied. On the other hand, different order picking policies might be used such as Batch picking where the orders would be batched together and the picking process carried out for whole required orders in a single picking round. Under batch and/or zoning picking policy, which is applied in most online retailers’ warehouses, products necessitate further processes such as consolidation, sorting, and sequencing. Sequencing of items is one of the important processes that lead to enhancing logistic operations. However, current approaches are not capable of fully fulfilling the dynamic changes, and therefore puzzle-based sequencing system with very high density and highly efficient floor space utilization has been successfully developed. Accordingly, two puzzle-solving methods are investigated; the game tree and the pathfinding algorithms. A-star is chosen based on pathfinding algorithms in order to find the shortest solution of the puzzle in which the sequencing time is decreased. Furthermore, the pre-sorting process is proposed to overcome the unsolvable configuration issue. The shape of the puzzle is discussed with several factors that affect the sorting steps, and numerically we found that the square shape is better than the rectangular one in terms of solution steps. Three introduced technical solutions strategies are proposed to increase the limitation of the puzzle; increasing the puzzle size, using multi-boards with the same puzzle boards sizes, and adding buffer conveyor. These strategies are explained and discussed in terms of the area used by the system and the total solution steps. Using multi-boards with the 8-puzzle board size was superior to other strategies. An arbitrary number of blanks in the puzzle was discussed with their effect on the puzzle capacity and maximum solution steps. Moreover, by carrying out double switching in one step with applying the block movement concept, the solution steps are minimized by a minimum of 1 step, an average of 4 steps, and a maximum of 10 steps in an 8-puzzle with 2 blanks placed in the corner of the puzzle, and the average reduction percentage of solution steps was 25%. The best strategy to sequence more than 8 boxes in one sequencing time is using multi-boards along with the main feeding conveyor with the shape and size of 8-puzzle with 2 blanks. The findings suggest that a puzzle-based sequencing system would be preferred for highly efficient floor space utilization as well as lower sequencing time compared to other systems.九州工業大学博士学位論文 学位記番号: 生工博甲第436号 学位授与年月日: 令和4年3月25日1 Introduction|2 Research Methodology|3 Results and Discussion|4 Conclusion and Future Work九州工業大学令和3年