Optimal 3D Compact AS/RS Storage Rack Design Considering The Operating Characteristics Of S/R Machine

Because the supply of land for logistics and storage is increasingly scarce in big cities,three-dimensional(3D)compact(multi-deep)automated storage and retrieval systems(AS/RSs)with less land occupation are widely used in newly designed warehouses;optimal AS/RS designs aiming to minimize the operation time are becoming increasingly critical.Scholars have done a lot of research on the issue,including the optimal sizes of the warehouse in optimization of the design,automation and control of the facilities in AS/RSs,and optimization in daily operations.Research on the optimal sizes of the warehouse is a basic but crucial part.Though there are a lot of literature before,there is always weakening of the real factors(such as storage policies,choosing the simple random storage;adopting uniform velocity model of the stackers,or taking approximate method for solving easily;only considering the cases of two-dimensional warehouse).This reduces the difficulties to solve the problems,but it also reduces its accuracy and applicability.This paper explores the design of an optimal rack for a 3D compact AS/RS under the full turnover-based storage policy.The acceleration and deceleration characteristics of storage and retrieval(S/R)machine are considered along the horizontal and vertical directions,to represent a real-world 3D compact AS/RS operation scenario more accurately.This makes our paper not only the most accurate,but also the most complicated and most difficult to solve.Solving this problem successfully will be an important breakthrough in the research of this field,and provide a reference to solve complex situations with similar level of difficulties for further research.We derive the expected retrieval time for single-command cycles by dividing the problem into three categories when adopting more accurate speed model,and manage to develop optimally designing storage rack model for a 3D compact AS/RS.From the model with extensive applicability,we can derive the optimal rack dimensions for various scenarios of any given capacity,S/R machine characteristics of the system and the ABC curve skewness characteristics of the stock keeping units(SKUs).Through further extension,we make that the absolute values of the stacker acceleration in acceleration and deceleration,need not to be equal to each other.Through applying this model,we also show that the full turnover-based storage policy is more efficient than the random storage policy.Moreover,we use a practical example to demonstrate the application of the proposed model.Finally,we discuss the shape factors and future research directions for the speed model.