Study On Optimal Design And Control Of Order Picking In Distribution Center

Distribution center as an important part of supply chain, the order picking impacts the performance of distribution center itself and extend to the operational efficiency of supply chain. All operations in distribution center, the role of order picking playing corresponds to heart of man and compressor of condition air. Order picking underperformance may lead to unsatisfactory service and high operational cost for the distribution center, and consequently for the whole supply chain. In order to operate efficiently, the order picking process needs to be designed and controlled optimally. Thus viewpoint and theme of the dissertation has a very important theory and practice significance for distribution center in mending the experiential operations, making the decision more scientific and rational, improving order picking efficiency, cutting operational cost, furthermore the competitive ability increase of the whole supply chain.Order picking operation in distribution center is studied in this papr. Based on some qualititative study, detailed quantitative study about design and control of order picking in distribution center from playout planning to several control strategies is conducted, which forms more systematic quantatitive study system about optimal design amd control of order picking in China. Concretely, the invonations are as follow.1,A model of layout for workcells, an algorithm about the model, and concept of SLP coordinate system are presented based on the Systematic Layout Planning (SLP) from R. Based on these, playout algorithm workflow of distribution center is designed in order to decide the relative location of several function zones in order picking system. layout model for man-to-part order picking system is build up. Then we slove the layout model by the simplest complete enumeration to an example, and some suggestions are put forword from the example.2,The similarity coefficient is redefined in the storage location assignment model based on workload balance when all the zone picker are working on the same order simultaneously. According to the practice of items having certain weight and volume, under the premise that the item actual quantity ordered is full considered, the conception of equivalent order number of items and its formulation are presented. the formulation of system ultilization is also put forward in order to examine the effect of stoage location assignment .When circumstance change, can also decide whether the storage locations should be adjusted or not by comparing the system utilization value befor adjust and after adjust. Simple to-and-fro picking model is build up. Then we slove the model by the density-turnover index rule to an example, and the usefulness of the model is verified.3,A mathematical model for order batching to reduce total travel distance is developed. Conceptions and their formulations of storage location similarity coefficient, aisle similarity coefficient and envelop distance have been presented and a cluster model of order bathing is constructed. At the same time, genetic algorithm base on envelop decoding for order batching is designed.4,The conception of balance delay be introduced to order picking system design, a typical hybrid order picking system with several picking zones and picking strategies is established based on one of the biggest IT distribution centers in our country. Taking time balance among picking zones as an objective, this paper adopts two criteria with minimum waiting time and balance delay to validate the nature of time balancing in the system by calculating the standard picking time in various picking zones respectively. A method of order picking operation design based on time balance is given. Meanwhile, an amended method is presented for the time of unbalancing during the designing process.