AI Framework Optimizes Warehouse Layouts

By Dr Silpaja Chandrasekar, PhDReviewed by Susha Cheriyedath, M.Sc.Jul 18 2024

In an article submitted to the arXiv* server, researchers introduced an artificial intelligence (AI)--driven framework for automated warehouse layout generation. They employed constrained beam search to optimize layouts, ensuring functional requirements were met within given spatial constraints.

*Important notice: arXiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Feasibility was assessed based on item accessibility, clearances, and aisle connectivity. A scoring function evaluated layouts considering storage capacity, access points, and accessibility costs: this approach facilitated rapid exploration and selection of optimal warehouse layouts across various dimensions, shapes, and door placements.

Background

Past work in warehouse management systems (WMS) has focused on enhancing operational efficiency to boost profitability by maximizing productivity, minimizing labor costs, and improving customer satisfaction. Optimal space utilization is critical within WMS, aiming to reduce the need for larger warehouses and efficiently manage inventory to minimize wasted space.

Though still prevalent, traditional manual layouts are less efficient for larger warehouses and prone to human error. Automated approaches using mathematical optimization methods like integer linear programming and genetic algorithms have been explored, yet they often encounter challenges related to flexibility and computational costs.

Warehouse Layout Optimization

The methodology centers on optimizing warehouse layouts for enhanced storage capacity, access points, navigation efficiency, and throughput during item retrieval. Initially, a diverse set of candidate layouts is generated through a novel algorithm based on tree search.

This algorithm operates within a discrete two-dimensional grid representing the warehouse space, incorporating elements like walls, door connections, aisles, storage zones, and pick faces. The process begins with a fully occupied grid and systematically explores potential layouts by introducing new aisles. Layouts not complying with functional and efficiency constraints are filtered out during the layout filtering step.

The analysts adopt beam search, a heuristic breadth-first search (BFS) approach, to manage the computational complexity of exhaustive tree search. This strategy allows for localized decision-making while restricting the search space, thereby promoting the discovery of diverse solutions. Adjusting the beam size optimizes the balance between exploration speed and depth, ensuring scalability in practical applications.

Layout evaluation uses a customized scoring function that integrates normalized metrics such as storage capacity, number of pick faces, and block store orientation. This function enables trade-offs between storage efficiency and accessibility, which is crucial for generating efficient layouts. Additionally, a connectivity score estimates relative throughput by assessing the average cumulative ratios of Interval between pairs of pick faces, aiding in selecting optimal layouts.

Following layout generation and scoring, a post-refinement phase applies operational constraints programmatically. It includes ensuring compliance with specific requirements such as pallet racking system specifications or accessibility pathways to critical equipment. These constraints are used iteratively to finalize layouts that meet operational needs before implementation.

Implementation details focus on optimizing the method for larger beam sizes using multiprocessing techniques to expedite exploration times. For example, experiments in medium-sized warehouse space (50 × 55) demonstrated an average processing time of 85 seconds for generating detailed Pareto plots, underscoring the method's practical scalability and efficiency in real-world scenarios.

Warehouse Layout Analysis

The layout generation process explored all combinations to generate a comprehensive set of optimal layouts tailored to a warehouse space. These layouts created a Pareto plot to visualize trade-offs between storage capacity and the number of pick faces. The Pareto front illustrates layouts that strike optimal balances, where increasing the number of pick faces reduces storage capacity. Connectivity scores were used to differentiate layouts with similar scores, prioritizing designs likely to enhance throughput.

Comparison between auto-generated optimal layouts and a manually designed layout revealed consistent improvements in pick faces and storage volume capacity, validating the method's effectiveness in optimizing warehouse layouts. Expert warehouse designers closely collaborated to verify the excellence of the layouts produced. Their feedback highlighted the process's user-friendliness and efficacy as a collaborative tool, significantly streamlining design efforts to achieve efficient warehouse layouts tailored to operational needs.

The generated Pareto plot visually represented the optimal layouts' trade-offs, showcasing the method's ability to effectively balance storage capacity and pick face numbers. Expert validation confirmed significant improvements over manually designed layouts, underscoring the method's practical benefits in warehouse layout optimization.

The collaborative approach with warehouse designers ensured user-friendly interaction and streamlined efforts to achieve tailored, efficient layouts. This iterative process of refinement and validation enhances confidence in deploying optimized warehouse configurations.

Summary

In conclusion, the study introduced an automated framework for generating optimal warehouse layouts using beam search, effectively balancing storage capacity, access points, and accessibility costs through a tailored scoring function. The method demonstrated versatility across various warehouse configurations, offering practical adaptability to user specifications.

Collaboration with expert warehouse designers validated the practicality and precision of generated layouts across diverse real-world scenarios, highlighting the potential for ongoing refinement and validation to enhance the tool's applicability and effectiveness in optimizing warehouse configurations.

*Important notice: arXiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.