Modeling of Parallel Movement for Deep-Lane Unit Load Autonomous Shuttle and Stacker Crane Warehousing Systems

Abstract

The autonomous shuttle and stacker crane (AC/SC) warehousing system, as a new automated deep-lane unit load storage/retrieval system, has been becoming more popular, especially for batch order fulfilment because of its high flexibility, low operational cost and improved storage capacity. This system consists of a shuttle sub-system that controls motion along the x-axis and a stacker crane sub-system that controls motion along the y-axis and z-axis. The combination of shuttles and a stacker crane performs storage and retrieval tasks. Modelling the parallel motion is an important design tool that can be used to calculate the optimal number of shuttles for a given configuration of the warehousing system. In this study, shuttle movements from one lane to another are inserted into the stock-keeping unit (SKU) task queue, and convert such that they are consistent with the retrieval tasks. The tasks are then grouped according to their starting lane, and converted to an assembly-line parallel job problem by analysing the operating mode with the objectives of minimising the total working time of the stacker crane and the wasted shuttle time. A time sequence mathematical model based on the motion of the shuttles and stacker crane is proposed, and an improved Pareto-optimal elitist non-dominated sorting genetic algorithm is used to solve this multi-objective optimization problem. The model is validated via a simulation study, and via a real-world warehousing case study. We go on to describe guidelines for the layout and configuration of AS/SC warehousing systems, including the optimal number of shuttles and number of x-axis storage cells of lanes, which can improve efficiency and minimise both capital investment and operating costs.

Relocation and storage assignment strategy evaluation in a multiple-deep tier captive automated vehicle storage and retrieval system with undetermined retrieval sequence

“…A widely used kinematic model has been applied to describe the shuttle carrier's and satellite vehicle's kinematic performance in similar research studies [4], [6], [7], [15], [18], [22], [23].…”

“…Random strategy (RAND) selects an empty storage location by using a random function. Many articles have studied a random strategy, especially during the storage process [4], [6], [7], [15], [18], [22], [23]. However, the selection is not always entirely random, as all empty storage locations are usually not considered.…”

Research on Design of Cross-Aisles Shuttle-Based Storage/Retrieval System Based on Improved Particle Swarm Optimization

“…A time sequence mathematical model based on the motion of the shuttles and stacker crane is proposed. An improved Pareto-optimal elitist non-dominated sorting genetic algorithm is used to solve the objectives of minimizing the total working time of the stacker crane and the wasted shuttle time [20]. Reference [21] proposes a hybrid algorithm based on the ant colony algorithm, and an adaptive extensive neighborhood search is submitted to solve the problem of system throughput.…”

“…The equipment with the lowest efficiency will limit the maximum sorting capacity of the system. Then according to ( 13), ( 16), ( 19), (20), the maximum throughput of the system is:…”

Digital Twins for Lighting Analysis: Literature Review, Challenges, and Research Opportunities

“…In addition, so far only one stacker crane per aisle has been implemented. (Wang et al, 2020) On the contrary, the shuttles of a DHPW can move in both directions of the plane and up to three stacker cranes per aisle have been coordinated and investigated in (Siciliano et al, 2022). To increase the throughput of a DHPW, specific order assignment strategies and specific stacker cranes' coordination policies (Siciliano et al, 2022) should be applied that take into consideration the complex nature of the connection between shuttle tier and multiple stacker cranes in a single aisle.…”