Automated Storage and Retrieval Systems from A-Z

Key takeaways

• Scalability: Systems can be easily expanded or adapted to meet changing business needs and growth.
• Optimized space use: AS/RS maximizes warehouse space, enabling high-density storage and efficient use of vertical and horizontal areas.‍
• Enhanced efficiency: Speeds up the process of storing and retrieving goods, which can significantly increase productivity.‍
• Reduced labor costs: Automation reduces the need for manual labor in storage and retrieval operations, lowering associated costs.‍
• Improved accuracy: Minimizes human errors in inventory management, leading to better inventory control and fewer picking errors.

What is an automated storage & retrieval system?

An AS/RS (Automated Storage and Retrieval System) is a technology-driven solution that automates the storage and retrieval of goods in a warehouse. It combines various elements, such as robots, digital controls, and sometimes storage racks, to create an efficient, automated system that handles goods of all types and sizes. Everything is coordinated by automation software to ensure smooth operations.

There are many types of AS/RS solutions. For example, cube storage systems store items in bins, while autonomous mobile robots (AMRs) and move items around the warehouse. Horizontal and vertical carousels use rotating shelves to quickly access items, while cranes, shuttles, and vertical lift modules (VLMs) generally move items in a fixed shelving structure. Some systems focus on different sizes, such as micro-, unit-, or mini-load systems, to handle various types of goods. All of these systems are managed by a warehouse management system (WMS) ⁠— the brain of the operation.

Furthermore, an AS/RS is not limited by size, and can support small, large, or multi-site warehouses, leveraging the various technologies and vehicles to automate the retrieval and deposition of high-volume loads, accurately and at speed.

The history of the first automated storage and retrieval system

The first AS/RS was developed by Demag in the 1950s, and by 1962, they installed the first fully automated warehouse for Bertelsmann, featuring a system that managed nearly 7 million books in a 20-meter-high facility. This innovation allowed for more efficient use of vertical space and reduced labor compared to traditional warehouses. Over the following decades, while the basic AS/RS design stayed the same, the technology became global, favored for its high-density storage capabilities, especially where labor and space were limited. Advances in processor power and warehouse control systems software since the 1980s have further advanced AS/RS, making it a leading solution in modern warehousing, significantly evolving from its original design.

Types of automated storage and retrieval systems

An automated storage and retrieval system is not just “one thing”. In fact, there is a wide variety of AS/RS options, including:

• Cube Storage AS/RS
• Unit-Load AS/RS Cranes (fixed-aisle & moveable aisle)
• Mini-Load AS/RS Cranes (fixed-aisle)
• Shuttle AS/RS
• Carousel-based AS/RS
• Vertical, horizontal, and robotic vertical lift module (VLM) AS/RS
• Micro-load (stocker) AS/RS
• Vertical sequence systems (VSMs) AS/RS
• Mobile robots (AGVs and AMRs)

Below is an overview of the different elements and variations within these:

Cube Storage AS/RS

The cube storage AS/RS not only maximizes storage space but also enhances speed and throughput. By eliminating the empty space found in traditional shelving, it offers high-density storage with efficient access to goods. This system consists of just a few key modules: inventory is stored in Bins, stacked like building blocks within an aluminum Grid. Robots travel on tracks along the top of the Grid, continuously retrieving and delivering Bins to Ports (warehouse workstations) as directed by the system, ensuring fast and continuous operations.

While some might wonder about Robots "digging" through stacks to retrieve Bins from deeper levels, this process is faster than expected. The advanced algorithms used in systems like AutoStore ensure that high-demand items are prioritized at the top, and even when digging is required, the speed of the Robots and the intelligent system design minimize any delays. This is a key factor in AutoStore’s high throughput, allowing it to process large volumes of orders swiftly and efficiently.

At the Ports, workers can rapidly access inventory for order fulfillment or restocking, while Robots return the Bins to the Grid for future use. The modular, building-block design of cube storage AS/RS allows for quick installation and easy scalability to meet growing demands. While items need to fit within the Bin dimensions (such as AutoStore’s largest Bin, which measures 449 mm x 649 mm x 425 mm), the system’s combination of space efficiency and high throughput makes it ideal for environments where speed and capacity are critical.

Unit-load AS/RS

Unit-load AS/RS systems are designed to cope with cumbersome and/or heavy loads covering weights between 1,000 and just over 5,000 pounds (about 2,267.96 kg). They are ideal for heavy pallets and often employ tall racks with narrow avenues accessed via a fixed-aisle or moveable-aisle crane to transport the goods in storage. They are ideal for locations where space for pallets is limited and where larger items need to be accessed at speed.

Fixed-aisle & moveable aisle crane unit-load AS/RS

With this system, narrow aisles of pallet racks are accessed via a mobile crane that can move vertically and horizontally along a set aisle to quickly access, collect, and move items in storage. A moveable aisle unit-load AS/RS differs in that the crane is not limited to one aisle, which avoids duplicating the crane for each and every aisle, thus saving on space and cost. One limiting factor is that the system relies completely on the mobile crane, and an aisle will be inaccessible during maintenance. 

Mini-load AS/RS

A mini-load AS/RS is ideal for handling smaller items, usually weighing no more than 75 pounds, compared to unit-load systems that can handle much heavier or larger loads. This AS/RS model often employs totes, trays, or cartons (or a combination of these elements) to transport inventory at speed, and is sometimes identified as a "case-handling/tote-stacking" AS/RS. It is a popular choice for stock keeping units (SKU) where space is at a premium, causing traditional carton shelving to be problematic. Area mini-load AS/RS is also a versatile option as a buffer for ordering products destined for picking or packaging, and can be used to replenish pick storage. These systems are limited by weight as well as size, which makes them less versatile than other systems.

Shuttle-based AS/RS

This model transports items via shuttle or robot following a track between the different areas in the warehouse/workspace, both horizontally and vertically. They can operate across a range of levels and deliver a wide variety of items via a tote or carton to a required location. Shuttles are instructed to retrieve items and deliver them via the exterior of the rack to a workstation or to a secondary conveyor. They come in a wide variety of designs, depending on the product and warehouse requirements. Limiting factors include that aisles of products can be inaccessible during maintenance and shuttles require more space than other systems.

AMR-based high-density AS/RS

An autonomous mobile robot (AMR) uses independent robots to navigate the racking, using multiple pathways to retrieve items for a specified tote or location. AMRs deliver these items to the ordering workstation, before taking on the next task. This versatile system offers excellent flexibility and efficiency, and the nature of AMRs means they can be easily scaled to meet changing demand, by adding more AMR units. The systems are highly complex, with advanced sensor packages and other autonomous elements demanding a higher level of technical support.

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Go-fer Bot AMR

The Go-fer system, named after burrowing gophers, uses specially designed shelves and racks that are moved via the AMR from below to the workstation. The shelves can be configured to take a wide variety of options such as boxes, pallets, or hanging arrangements depending on the items in question. The AMRs lift and transport the whole unit to the workstation, before returning. This offers a high-density storage solution, and can be easily and affordably scaled to meet the needs of the business. This system, like the shuttle system, requires more floor space to move the shelves and store them in queues.

Stacker-bot

A newly developed AMR AS/RS stacker-bot extracts several totes or cases from a shelving rack, then delivers the totes or cases to an awaiting conveyor, secondary AMR, or workstation. The Stacker-Bot can combine delivery and returns on the fly, providing a nimble, efficient, and cost-effective system. They require more space to operate, as the units vary in size, and so require more space set aside for navigation.

Carousel-based AS/RS

Carousel-based AS/RS systems are the oldest form of AS/RS, consisting of a track suspending a variety of items or storage options (think of dry cleaners with hanging clothes). This will cycle to deliver a particular item or bin to a workstation as required. They come in a variety of designs, from a horizontal model delivering items in a line to a vertical carousel where bins move in an up-and-down loop. These systems are ideal for smaller items that can move at speed. Another variation includes the robotic horizontal carousel AS/RS, which offers an automated system involving up to three tiers of carousel with totes at every level. Limiting factors are that they can be more difficult to expand and they demand a considerable amount of space.

Vertical lift module (VLM)

This system is characterized by a picker at the center of a stack of racks, which moves back and forth to select ordered items and deliver them to a workstation or conveyor. They are often enclosed with the arm moving freely within the racking space. Once the order is fulfilled, the VLM will return the storage unit to the correct location, before taking on the next task. The trays themselves can be fixed or mobile, leading to highly efficient management of a complex inventory. A micro-load stocker is very similar to a VLM, and is ideal for high density warehouses requiring an AS/RS for buffering, sequencing, and point-of-use goods. A micro-load stocker can consist, for example, of a series of robots operating within an enclosed storage grid, delivering bins to a conveyor. Like the aisle-based cranes, the VLM/stocker is highly reliant on certain parts that can cause the system to grind to a halt during maintenance.

Vertical Sequence Module (VSM)

This system orders retrieved bins in a sequence, providing an efficient solution for high-density, high-volume warehouse spaces. The order sequence can be retrieved via another system such as an AMR or conveyor and delivers them in a specific order. This system can also be added as an enhancement to existing AS/RS installations, thus improving efficiency and productivity and reducing demands on floor space. Like the VLM above, the system can be subject to delays during maintenance when certain components are out of action.

Workflow in automated storage and retrieval-equipped warehouses

Initial Stages: Before AS/RS activation

Goods receiving: The warehouse process starts when goods arrive at the receiving dock. Each item is checked, logged into the warehouse management system (WMS), and labeled with barcodes or RFID tags that enable tracking throughout its stay in the warehouse.

Preparation for storage: Before being stored, items undergo quality checks and sorting based on type, size, and storage needs. This sorting ensures that items are stored in a manner that optimizes space and accessibility, adhering to specific storage requirements (like temperature or humidity control).

AS/RS activation: Storage and retrieval

Storage: Once the items are processed, the AS/RS takes over. Based on instructions from the WMS, the AS/RS transports items to their designated locations in the storage area. This is typically a high-density setup that maximizes vertical and horizontal space. The system places items in locations that optimize retrieval efficiency, often based on the frequency of access and the nature of the goods.

Retrieval: When an order is placed, the WMS communicates with the AS/RS to retrieve the required items. The system identifies the most efficient route to pick all items from their storage locations and delivers them to the order fulfillment area. This automation minimizes the retrieval time and enhances the accuracy of order processing.

Final stages: After AS/RS fulfillment

Order assembly: In the order fulfillment area, workers or automated systems assemble orders. This might involve picking additional items not handled by the AS/RS, combining items into shipping containers, and performing final checks for order accuracy.

Packing and shipping preparation: Completed orders are then packed, labeled with shipping information, and staged in the loading area. The packing process ensures that items are securely prepared for transit to prevent damage.

Shipping: The final step involves loading packed orders onto transport vehicles according to the shipping schedules managed by the transportation management system (TMS). This system optimizes delivery routes and schedules to ensure timely deliveries.

Ongoing operations and customer service

Post-shipping, the warehouse management system continues to update inventory levels and order statuses, providing real-time data for customer inquiries and future order planning. Customer service handles any issues with order fulfillment, returns, or exchanges, ensuring that the end-to-end process maintains high standards of customer satisfaction.

By segmenting these stages, it becomes clear how AS/RS is crucial for not only storage and retrieval phases but operates as part of a larger system that ensures efficiency and accuracy from the receipt of goods to their final delivery.

So, here's a concise summary of the tasks an automated storage and retrieval system is involved in, in a warehouse:

• Receiving data integration: Integrates incoming goods information for storage preparation.
• Automated storage: Efficiently stores items in designated locations.
• Inventory management: Manages and updates inventory data.
• Retrieval of goods: Automatically retrieves items based on orders.
• Order consolidation: Organizes retrieved items for order fulfillment.
• Transport to packing stations: Delivers items to packing areas.
• Data reporting: Updates the WMS on task completions and inventory status.

True benefits of automated storage and retrieval systems

Integrating automated storage and retrieval systems (AS/RSs) into your warehouse operations can significantly enhance performance and efficiency. Here’s how an AS/RS can elevate your operations:

• Increased storage density: AS/RS utilizes vertical space effectively, allowing for a more compact storage arrangement. This maximizes warehouse space, enabling you to store more items without expanding the physical footprint.
• Enhanced operational efficiency: Automation reduces the time required for storing and retrieving items. AS/RS systems streamline these processes, increasing the speed of operations and reducing bottlenecks, especially during peak demand periods.
• Improved inventory accuracy: AS/RS systems are highly accurate, minimizing human errors in inventory management. This precision ensures better inventory control, reduces mispicks, and enhances overall reliability of the inventory data.
• Labor cost savings: By automating repetitive tasks, AS/RS reduces the need for manual labor in storage and retrieval operations. This can lead to significant savings in labor costs and reduce issues related to workforce management.
• Enhanced safety: AS/RS systems minimize the need for workers to engage in potentially hazardous activities, such as working at heights or manually moving heavy items. This can lead to a safer work environment and reduce the risk of workplace accidents.
• Scalability and flexibility: AS/RS systems can be easily scaled to accommodate growth in inventory and operations. Additional modules can be integrated without major disruptions, allowing for flexibility in response to changing business needs.
• Increased order fulfillment speed: With faster retrieval times and efficient order processing, AS/RS systems help in meeting customer demands more quickly and accurately, potentially increasing customer satisfaction and retention.
• Reduced operating costs: Efficient space use and reduced energy consumption, along with lower labor costs, contribute to overall lower operating expenses.

By integrating AS/RS, you can achieve a more robust, efficient, and safer operation that supports current needs and scales for future growth. This modernization not only optimizes warehouse operations but also provides a competitive edge in logistics and supply chain management.

10 Signs it's time for an automated storage and retrieval system!

If you're wondering whether your warehouse or distribution center might benefit from implementing an automated storage and retrieval system, here are ten signs that it might be time to consider such an upgrade:

1. Frequent picking errors: High error rates in picking can indicate inefficiencies that AS/RS can address.
2. Limited storage space: If you’re running out of space, AS/RS can maximize the use of vertical and horizontal space.
3. Increasing labor costs: Rising costs associated with manual labor for storage and retrieval tasks could be mitigated with AS/RS.
4. High employee turnover: Difficulty in retaining warehouse staff can be alleviated by automating repetitive tasks.
5. Growing safety concerns: Increasing incidents or near misses in the warehouse suggest a need for safer, automated solutions.
6. Difficulty meeting order deadlines: Struggling to keep up with customer demands can be a sign that more efficient systems are needed.
7. Scaling operations: If your business is expanding, AS/RS can efficiently scale to meet increased inventory and throughput demands.
8. High energy costs: Inefficient use of warehouse space and equipment can lead to excessive energy consumption, which AS/RS can optimize.
9. Inventory inaccuracies: Persistent issues with inventory accuracy can be resolved with the precise control offered by AS/RS.
10. Inadequate response to peak demands: If your current system falters during peak periods, AS/RS can provide the necessary robustness.

Choosing the right AS/RS for your operations

When you’ve come to the conclusion that investing in an automated storage and retrieval system is a good idea, consider the following factors to match the choice of system to your specific operational needs:

• Type of load: Evaluate what items you are storing. Different systems are better for different loads, e.g., pallets, cases, or individual items.
  • Unit-load AS/RS: Ideal for handling large items or palletized goods.
  • Mini-load AS/RS: Best for smaller items, typically stored in bins or boxes.
  • Carousel systems: Effective for high-speed retrieval of small, lightweight items.
  • Vertical lift modules (VLMs): Suitable for a variety of item sizes, especially where space is limited.

• Throughput requirements: Consider the volume of items that need to be stored and retrieved within a given time frame. High-throughput environments might benefit from faster, more dynamic systems.
• Warehouse layout: The physical layout of your facility can influence the type of AS/RS that is most appropriate. Some systems require more vertical space, while others might spread horizontally.
• Integration capabilities: Ensure the AS/RS can integrate seamlessly with your existing warehouse management software and other ERP systems for smooth operations.
• Budget constraints: Evaluate the cost relative to the expected ROI. Higher upfront costs might be justified by longer-term savings in labor, efficiency, and accuracy.
• Future scalability: Consider how easily the system can be expanded or modified as your business grows and changes.

By assessing these factors, you can choose an AS/RS solution that not only meets your current needs but also supports future growth and efficiency improvements. This strategic investment can transform your operations, enhancing competitiveness and customer satisfaction.

Choosing the right AS/RS for your industry

Selecting the appropriate AS/RS also depends on your specific industry:

• E-commerce and retail: These sectors often require handling a variety of item sizes and rapid fulfillment rates. Mini-load AS/RS or carousel systems are typically suitable for their ability to handle small to medium-sized goods with high speed and accuracy, ideal for quick picking of individual orders. Additionally, the AutoStore cube storage system is highly effective in these industries due to its high-density storage capability and extremely efficient use of space, making it perfect for warehouses with a high volume of diverse, smaller items.
• Automotive and manufacturing: Industries dealing with large, heavy parts typically benefit from unit-load AS/RS, which are designed to handle heavier loads like pallets of components or assemblies, facilitating the storage and retrieval of bulky or heavy items efficiently.
• Food and beverage: These industries benefit from AS/RS solutions that can operate in cold environments and reduce human contact with food items. Mobile racking systems, which operate well in cold storage environments, are ideal for maximizing space and maintaining product integrity.
• Pharmaceuticals: Stringent control over inventory is crucial due to safety and compliance issues. Vertical Lift Modules (VLMs) are effective here, providing secure, enclosed storage that can be adjusted to accommodate a range of product sizes while ensuring easy access and accurate tracking.
• Publishing and media: Carousel systems are often a good choice for managing large volumes of books, CDs, or other media, allowing for efficient, high-density storage and easy retrieval.
• Aerospace: This industry, where components may be both large and require precise handling, might use a combination of unit-load and mini-load AS/RS to manage different sizes and shapes of parts and tools needed for aircraft manufacturing and maintenance.

Evaluating the cost and ROI of AS/RS: Is it worth it?

When considering an automated storage and retrieval system for your warehouse, it's important to factor in the initial investment and ongoing operational costs. The cost largely depends on the type and complexity of the system — whether it’s a unit-load, mini-load, or carousel system — as well as the specific needs of your warehouse layout. Customizations to fit the existing space and the integration with current warehouse management systems can also add to the expense.

The cost of installing an AS/RS includes not just the physical equipment but also software for inventory management and real-time tracking, plus the expenses related to installation, commissioning, and necessary training for staff. Moreover, ongoing maintenance, support, and energy consumption contribute to the total cost of ownership. Regulatory compliance and potential future scalability should also be considered, as these can impact both initial costs and future expansion capabilities.

Despite these costs, investing in an AS/RS can lead to significant savings and efficiency gains in the long run. Businesses typically see a return on investment (ROI) from an AS/RS through improved inventory accuracy, increased storage density, and labor cost reductions. The time frame for realizing these returns can vary but often begins to materialize within a few years after implementation, depending on the system’s efficiency and the scale of operations. This makes AS/RS a worthwhile consideration for warehouses looking to enhance productivity and reduce long-term operating costs.

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The innovative AutoStore system: A versatile AS/RS solution

The AutoStore system is a highly innovative automated storage and retrieval system that stands out in the realm of warehouse automation for its compact design and efficiency. AutoStore is renowned for its unique cube-based storage infrastructure where bins are stacked vertically and horizontally, maximizing the use of available space. This system is driven by Robots that navigate the top of the storage Grid to retrieve and replace Bins as needed.

What makes AutoStore particularly appealing is its adaptability to various industries. Its high-density storage setup and quick retrieval capabilities make it ideal for e-commerce, retail, electronics, and pharmaceuticals, among others. These sectors benefit from the AutoStore ability to handle a diverse range of product types and sizes, facilitating rapid order fulfillment and efficient inventory management.

The system's flexibility also extends to its scalability and ease of integration with existing warehouse management systems, allowing businesses to expand or modify their storage capacities with minimal disruption. This adaptability, combined with the potential for significantly reduced footprint and enhanced order accuracy, makes AutoStore an exemplary solution for industries looking to innovate their warehouse operations and improve overall efficiency.

Conclusion

Investing in an automated storage and retrieval system offers numerous operational benefits, from space optimization and enhanced efficiency to cost savings and improved accuracy. With scalable solutions like the AutoStore system, businesses can adapt to market demands and grow efficiently, ensuring a competitive edge in today’s fast-paced market environments.

FAQ

What does an automated storage and retrieval system do?

An automated storage and retrieval system (AS/RS) automates the process of storing and retrieving items in a warehouse. It efficiently manages inventory and optimizes space usage by using robotic systems and computer control to place and retrieve goods from designated storage locations.

What are the different systems of automated storage and retrieval?

There are several types of AS/RS, including:

• Unit-load AS/RS: Designed for handling large items or pallets.
• Mini-load AS/RS: Handles smaller items typically stored in bins or trays.
• Carousel systems: Rotate items to a fixed retrieval point, suitable for small, light items.
• Vertical lift modules (VLMs): Consist of vertically arranged trays, retrieved by an automated inserter/extractor.
• AutoStore: A grid-based system where Robots navigate on top of a cubic storage Grid to access bins.

What is the purpose of an AS/RS system?

The purpose of an ASRS system is to improve efficiency, accuracy, and safety in warehouse operations. It reduces labor costs, increases storage density, and enhances the speed and precision of the inventory management process.

How is AS/RS used today?

Today, ASRS is widely used across various industries such as manufacturing, retail, e-commerce, pharmaceuticals, and more for efficient warehouse management. It supports operations by providing rapid access to items, streamlining the picking process, and enabling more effective use of warehouse space. ASRS is integral to modern logistics and supply chain strategies, particularly in environments demanding high throughput and accuracy.