关键词: Auto Store, AGV路径规划, AGV冲突, 改进A*算法, 仓储系统

Abstract:

Auto Store, a new compact and dense storage system, has many characteristics, such as more short-distance relocation operations, more AGV conflicts at the top level, and more structural corners of shelves, therefore, an offline online two-stage AGV scheduling method is proposed. In the off-line path planning stage, an improved two-level A* algorithm is given. On the basis of topological graph modeling and dividing the search area, the upper layer seeks the feasible region by considering the conflict heuristic function and the cost function considering turning, and the lower level searches the optimal path based on this area. In the operation phase of online AGV, the backoff strategy and route replanning strategy are extended for the conflict between two AGVs; for multiple AGV conflicts, a regional collision avoidance decision strategy based on greedy algorithm is proposed to control the scale of the problem. Finally, Flexsim simulation is used to verify the results. The results show that compared with the standard A* algorithm, the improved A* algorithm can obtain the initial path scheme with less conflicts while ensuring the search efficiency; compared with the priority strategy, the regional collision avoidance strategy can reduce the waiting time of AGV; the combination of the two can shorten the overall job completion time, and with the increase of the number of AGVs and tasks, the advantages of the improved A* algorithm are better obviously.

Key words: Auto Store, AGV path planning, AGV conflict, improved A* algorithm, storage system