An automated storage and retrieval system (ASRS or AS/RS) consists of a variety of computer-controlled systems for automatically placing and retrieving loads from defined storage locations. Automated storage and retrieval systems (AS/RS) are typically used in applications where:
* There is a very high volume of loads being moved into and out of storage
* Storage density is important because of space constraints
* No value is added in this process (no processing, only storage and transport)
* Accuracy is critical because of potential expensive damages to the load
An AS/RS can be used with standard loads as well as nonstandard loads, meaning that each standard load can fit in a uniformly-sized volume; for example, the film canisters in the image of the Defense Visual Information Center are each stored as part of the contents of the uniformly sized metal boxes, which are shown in the image. Standard loads simplify the handling of a request of an item. In addition, audits of the accuracy of the inventory of contents can be restricted to the contents of an individual metal box, rather than undergoing a top-to-bottom search of the entire facility, for a single item.
They can also be used in
self storage places.
Overview
AS/RS systems are designed for automated storage and retrieval of parts and items in manufacturing, distribution, retail, wholesale and institutions. They first originated in the 1960s, initially focusing on heavy pallet loads but with the evolution of the technology the handled loads have become smaller.
The systems operate under computerized control, maintaining an inventory of stored items. Retrieval of items is accomplished by specifying the item type and quantity to be retrieved. The computer determines where in the storage area the item can be retrieved from and schedules the retrieval. It directs the proper automated storage and retrieval machine (SRM) to the location where the item is stored and directs the machine to deposit the item at a location where it is to be picked up. A system of conveyors and or automated guided vehicles is sometimes part of the AS/RS system. These take loads into and out of the storage area and move them to the manufacturing floor or loading docks. To store items, the pallet or tray is placed at an input station for the system, the information for inventory is entered into a computer terminal and the AS/RS system moves the load to the storage area, determines a suitable location for the item, and stores the load. As items are stored into or retrieved from the racks, the computer updates its inventory accordingly.
The benefits of an AS/RS system include reduced labor for transporting items into and out of inventory, reduced
inventory levels, more accurate tracking of inventory, and space savings. Items are often stored more densely than in systems where items are stored and retrieved manually.
Within the storage, items can be placed on trays or hang from bars, which are attached to chains/drives in order to move up and down. The equipment required for an AS/RS include a storage & retrieval machine (SRM) that is used for rapid storage and retrieval of material. SRMs are used to move loads vertically or horizontally, and can also move laterally to place objects in the correct storage location.
The trend towards Just In Time production often requires sub-pallet level availability of production inputs, and AS/RS is a much faster way of organizing the storage of smaller items next to production lines.
The Material Handling Institute of America (MHIA), the non-profit trade association for the material handling world, and its members have categorised AS/RS into two primary segments: Fixed Aisle and Carousels/Vertical Lift Modules (VLMs). Both sets of technologies provide automated storage and retrieval for parts and items, but use different technologies. Each technology has its unique set of benefits and disadvantages. Fixed Aisle systems are characteristically larger systems whereas carousels and Vertical Lift Modules are used individually or grouped, but in small to medium-sized applications.
A fixed-aisle AS/R machine (stacker crane) is one of two main designs: single-masted or double masted. Most are supported on a track and ceiling guided at the top by guide rails or channels to ensure accurate vertical alignment, although some are suspended from the ceiling. The 'shuttles' that make up the system travel between fixed storage shelves to deposit or retrieve a requested load (ranging from a single book in a library system to a several ton pallet of goods in a warehouse system). The entire unit moves horizontally within an aisle, while the shuttles are able to elevate up to the necessary height to reach the load, and can extend and retract to store or retrieve loads that are several positions deep in the shelving. A semi-automated system can be achieved by utilizing only specialized shuttles within an existing rack system.

Another AS/RS technology is known as shuttle technology. In this technology the horizontal movement is made by independent shuttles each operating on one level of the rack while a lift at a fixed position within the rack is responsible for the vertical movement.
By using two separate machines for these two axes the shuttle technology is able to provide higher throughput rates than stacker cranes.
Storage and Retrieval Machines pick up or drop off loads to the rest of the supporting transportation system at specific stations, where inbound and outbound loads are precisely positioned for proper handling.
In addition, there are several types of Automated Storage & Retrieval Systems (AS/RS) devices called Unit-load AS/RS, Mini-load AS/RS, Mid-Load AS/RS, Vertical Lift Modules (VLMs), Horizontal Carousels and Vertical Carousels. These systems are used either as stand-alone units or in integrated workstations called pods or systems. These units are usually integrated with various types of pick to light systems and use either a microprocessor controller for basic usage or inventory management software. These systems are ideal for increasing space utilization up to 90%, productivity levels by 90%, accuracy to 99.9%+ levels and throughput up to 750 lines per hour/per operator or more depending on the configuration of the system.
Horizontal carousels

Robotic Inserter/Extractor devices can be used for horizontal carousels. The robotic device is positioned in the front or rear of up to three horizontal carousels tiered high. The robot grabs the tote required in the order and often replenishes at the same time to speed up throughput. The tote(s) are then delivered to a conveyor, which routes it to a work station for picking or replenishing. Up to eight transactions per minute per unit can be done. Totes or containers up to 36" x 36" x 36" can be used in a system.
On a simplistic level, horizontal carousels are also often used as "rotating shelving". With simple "fetch" command, items are brought to the operator and otherwise wasted space is eliminated.
AS/RS Applications: Most applications of AS/RS technology have been associated with warehousing and distribution operations. An AS/RS can also be used to store raw materials and work in process in manufacturing. Three application areas can be distinguished for AS/RS: (1) Unit load storage and handling, (2) Order picking, and (3) Work in process storage. Unit load storage and retrieval applications are represented by unit load AS/RS and deep-lane storage systems. These kinds of applications are commonly found in warehousing for finishing goods in a distribution center, rarely in manufacturing. Deep-lane systems are used in the food industry. As described above, order picking involves retrieving materials in less than full unit load quantities. Minilpass, man-on board, and items retrieval systems are used for this second application area.
Work in process
Work in process or work-in-process, (WIP), work in progress (WIP), goods in process, or in-process inventory refers to a company's partially finished goods waiting for completion and eventual sale, or the value of these items. The term is used in ...
storage is a more recent application of automated storage technology. While it is desirable to minimize the amount of work in process, WIP is unavoidable and must be effectively managed. Automated storage systems, either automated storage/retrieval systems or carousel systems, represent an efficient way to store materials between processing steps, particularly in batch and job shop production. In high production, work in process is often carried between operations by conveyor system, which this serve both storage and transport functions.
Inventory Category-specific AS/RS
Each inventory category—raw materials, work-in-process, and finished goods—requires its own specialized Automated Storage and Retrieval System (AS/RS). Particularly for work-in-process (WIP) inventories, due to variations in manufacturing processes, the AS/RS systems are significantly different in design and function, tailored specifically to match unique handling, storage, and retrieval requirements
Installed applications
Installed applications of this technology can be wide-ranging. In some libraries, such as at
University of Nevada, Reno
The University of Nevada, Reno (Nevada, the University of Nevada, or UNR) is a Public university, public Land-grant university, land-grant research university in Reno, Nevada, United States. It is the state's flagship public university and prim ...
library, such a system is employed to retrieve books. Still others in use involve retrieval of bicycles from a
bicycle tree, as in the case of systems in Japan.
Institutions using automated storage and retrieval systems
Some examples of academic institutions using automated storage and retrieval systems are;
*
University of British Columbia
The University of British Columbia (UBC) is a Public university, public research university with campuses near University of British Columbia Vancouver, Vancouver and University of British Columbia Okanagan, Kelowna, in British Columbia, Canada ...
,
Vancouver
Vancouver is a major city in Western Canada, located in the Lower Mainland region of British Columbia. As the List of cities in British Columbia, most populous city in the province, the 2021 Canadian census recorded 662,248 people in the cit ...
,
British Columbia
British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...
*
California State University, Long Beach,
Long Beach, California
Long Beach is a coastal city in southeastern Los Angeles County, California, United States. It is the list of United States cities by population, 44th-most populous city in the United States, with a population of 451,307 as of 2022. A charter ci ...
*
California State University, Northridge
California State University, Northridge (CSUN or Cal State Northridge), is a public university in the Northridge neighborhood of Los Angeles, California, United States. With a total enrollment of 36,848 students (as of Fall 2024), it has the ...
,
Northridge,
California
California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...
*
University of Central Florida,
Orlando,
Florida
Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...
*
Chicago State University
Chicago State University (CSU) is a Historically black colleges and universities, predominantly black (PBI) public university in Chicago, Illinois, United States. It includes an honors program for undergraduates and offers bachelor's and master ...
,
Chicago
Chicago is the List of municipalities in Illinois, most populous city in the U.S. state of Illinois and in the Midwestern United States. With a population of 2,746,388, as of the 2020 United States census, 2020 census, it is the List of Unite ...
,
Illinois
Illinois ( ) is a U.S. state, state in the Midwestern United States, Midwestern United States. It borders on Lake Michigan to its northeast, the Mississippi River to its west, and the Wabash River, Wabash and Ohio River, Ohio rivers to its ...
*
University of Chicago
The University of Chicago (UChicago, Chicago, or UChi) is a Private university, private research university in Chicago, Illinois, United States. Its main campus is in the Hyde Park, Chicago, Hyde Park neighborhood on Chicago's South Side, Chic ...
,
Chicago
Chicago is the List of municipalities in Illinois, most populous city in the U.S. state of Illinois and in the Midwestern United States. With a population of 2,746,388, as of the 2020 United States census, 2020 census, it is the List of Unite ...
,
Illinois
Illinois ( ) is a U.S. state, state in the Midwestern United States, Midwestern United States. It borders on Lake Michigan to its northeast, the Mississippi River to its west, and the Wabash River, Wabash and Ohio River, Ohio rivers to its ...
*
Colgate University
Colgate University is a Private university, private college in Hamilton, New York, United States. The Liberal arts colleges in the United States, liberal arts college was founded in 1819 as the Baptist Education Society of the State of New York ...
,
Hamilton, New York
Hamilton is a Administrative divisions of New York#Town, town in Madison County, New York, Madison County, New York (state), New York, United States. The population was 6,379 at the 2020 census. The town is named after American Founding Father ...
*
Cornell University
Cornell University is a Private university, private Ivy League research university based in Ithaca, New York, United States. The university was co-founded by American philanthropist Ezra Cornell and historian and educator Andrew Dickson W ...
,
Ithaca,
New York
*
Defense Visual Information Center,
March Air Reserve Base,
Riverside County, California
Riverside County is a County (United States), county located in the Southern California, southern portion of the U.S. state of California. As of the 2020 United States Census, 2020 census, its population was 2,418,185, making it the fourth-most ...
*
Eastern Michigan University
Eastern Michigan University (EMU, EMich, Eastern Michigan or simply Eastern) is a public university, public research university in Ypsilanti, Michigan, United States. Founded in 1849 as the Michigan State Normal School, it was the fourth normal ...
,
Ypsilanti, Michigan
Ypsilanti ( ), commonly shortened to Ypsi ( ), is a college town and city located on the Huron River in Washtenaw County, Michigan, Washtenaw County in the U.S. state of Michigan. As of the 2020 United States census, 2020 census, the city's popu ...
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Georgia Southern University,
Statesboro, Georgia
Statesboro is the most populous city in and the county seat of Bulloch County, Georgia, United States. Located in the southeastern part of the state, its population was 33,438 at the 2020 United States census, 2020 census. It is the principal city ...
*
Grand Valley State University,
Grand Rapids
Grand Rapids is the largest city and county seat of Kent County, Michigan, United States. With a population of 198,917 at the 2020 United States census, 2020 census and estimated at 200,117 in 2024, Grand Rapids is the List of municipalities ...
,
Michigan
Michigan ( ) is a peninsular U.S. state, state in the Great Lakes region, Great Lakes region of the Upper Midwest, Upper Midwestern United States. It shares water and land boundaries with Minnesota to the northwest, Wisconsin to the west, ...
*
Liberty University,
Lynchburg, Virginia
Lynchburg is an independent city (United States), independent city in the Commonwealth (U.S. state), Commonwealth of Virginia in the United States. First settled in 1757 by ferry owner and Abolitionism, abolitionist John Lynch (1740–1820), J ...
*
University of Limerick
University of Limerick (UL) () is a Public university, public research university institution in Limerick, Republic of Ireland, Ireland. Founded in 1972, as the National Institute for Higher Education, Limerick, it became a university in Septemb ...
, Limerick (Ireland)
*
University of Louisville
The University of Louisville (UofL) is a public university, public research university in Louisville, Kentucky, United States. It is part of the Kentucky state university system. Chartered in 1798 as the Jefferson Seminary, it became in the 19t ...
,
Louisville, Kentucky
Louisville is the List of cities in Kentucky, most populous city in the Commonwealth of Kentucky, sixth-most populous city in the Southeastern United States, Southeast, and the list of United States cities by population, 27th-most-populous city ...
*
Macquarie University
Macquarie University ( ) is a Public university, public research university in Sydney, New South Wales, Australia. Founded in 1964 by the New South Wales Government, it was the third university to be established in the Sydney metropolitan area. ...
,
Sydney
Sydney is the capital city of the States and territories of Australia, state of New South Wales and the List of cities in Australia by population, most populous city in Australia. Located on Australia's east coast, the metropolis surrounds Syd ...
,
Australia
Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...
*
Marywood University,
Scranton,
Pennsylvania
Pennsylvania, officially the Commonwealth of Pennsylvania, is a U.S. state, state spanning the Mid-Atlantic (United States), Mid-Atlantic, Northeastern United States, Northeastern, Appalachian, and Great Lakes region, Great Lakes regions o ...
*
University of Missouri–Kansas City,
Kansas City, Missouri
Kansas City, Missouri, abbreviated KC or KCMO, is the largest city in the U.S. state of Missouri by List of cities in Missouri, population and area. The city lies within Jackson County, Missouri, Jackson, Clay County, Missouri, Clay, and Pl ...
*
University of Nevada, Las Vegas
The University of Nevada, Las Vegas (UNLV) is a Public university, public Land-grant university, land-grant research university in Paradise, Nevada, United States. The campus is about east of the Las Vegas Strip. It was formerly part of the ...
*
University of Nevada, Reno
The University of Nevada, Reno (Nevada, the University of Nevada, or UNR) is a Public university, public Land-grant university, land-grant research university in Reno, Nevada, United States. It is the state's flagship public university and prim ...
*
UTS Library, University of Technology Sydney
*
North Carolina State University
North Carolina State University (NC State, North Carolina State, NC State University, or NCSU) is a public university, public Land-grant university, land-grant research university in Raleigh, North Carolina, United States. Founded in 1887 and p ...
,
Raleigh,
North Carolina
North Carolina ( ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, South Carolina to the south, Georgia (U.S. stat ...
*
Santa Clara University,
Santa Clara,
California
California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...
*
Sonoma State University
Sonoma State University (SSU, Sonoma State, or Sonoma) is a public university in Sonoma County, California, United States. It is part of the California State University system. Sonoma State offers 92 bachelor's degree programs, 19 master's de ...
,
Rohnert Park,
California
California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...
*
Tri-County Technical College, Pendleton, South Carolina
*
University of Utah
The University of Utah (the U, U of U, or simply Utah) is a public university, public research university in Salt Lake City, Utah, United States. It was established in 1850 as the University of Deseret (Book of Mormon), Deseret by the General A ...
,
Salt Lake City, Utah
Salt Lake City, often shortened to Salt Lake or SLC, is the List of capitals in the United States, capital and List of cities and towns in Utah, most populous city of the U.S. state of Utah. It is the county seat of Salt Lake County, Utah, Salt ...
*
Utah State University
Utah State University (USU or Utah State) is a public university, public land grant colleges, land-grant research university with its main campus in Logan, Utah, United States. Founded in 1888 under the Morrill Land-Grant Acts as Utah's federal ...
,
Logan,
Utah
Utah is a landlocked state in the Mountain states, Mountain West subregion of the Western United States. It is one of the Four Corners states, sharing a border with Arizona, Colorado, and New Mexico. It also borders Wyoming to the northea ...
*
Christopher Center,
Valparaiso University
Valparaiso University (Valpo) is a private university in Valparaiso, Indiana, United States. It is an independent Lutheran university with five colleges. It enrolls nearly 2,300 students and has a campus.
The university is known for its Luthe ...
,
Valparaiso, Indiana
*
Waseda University
Waseda University (Japanese: ), abbreviated as or , is a private university, private research university in Shinjuku, Tokyo. Founded in 1882 as the Tōkyō Professional School by Ōkuma Shigenobu, the fifth Prime Minister of Japan, prime ministe ...
,
Tokyo
Tokyo, officially the Tokyo Metropolis, is the capital of Japan, capital and List of cities in Japan, most populous city in Japan. With a population of over 14 million in the city proper in 2023, it is List of largest cities, one of the most ...
(
Japan
Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...
)
Types
* Vertical Lift Storage Modules (VLSM) - These are also called vertical lift automated storage/retrieval systems. All of the next AS/RS types are designed around a horizontal aisle. The same principle of using a center aisle to access loads is used, except that the aisle is vertical. Vertical lift storage modules, some with heights of 10 meters or more, are capable of holding large inventories while saving valuable floor space in the factory.
* Unit load stackers - The unit load stackers is typically a large automated system designed to handle unit loads stored on pallets or in other standard containers. The system is computer controlled, and the S/R machines are automated and designed to handle the unit load containers.
* ASRS Gantry Robots - These are a type of Automated Storage/Retrieval Systems used in warehousing and logistics sectors. Some common uses for these are in the Tire Industry for stacking tire inventory. Most of these systems span 50–60 ft in width and average 200–300 feet in length. These systems use End Effectors a.k.a. End of Arm Tooling to pick and place the tire stacks from conveyors.
Man-aboard systems
A man-aboard system can provide significant floorspace savings over manual or forklift operations but is not truly an AS/RS, as the operation is still manual. Storage system heights are not limited by the reach height of the order picker, as the picker rides along on the platform as it is moved vertically or horizontally to the various storage locations. Shelves or storage cabinets can be stacked as high as floor loading, weight capacity, throughput requirements, and/or ceiling heights will permit. Man-aboard storage and retrieval systems are far and away the most expensive picker-to-stock equipment alternative but are less expensive than a fully automated system. Aisle-captive storage/retrieval machines reaching heights up to cost around $125,000. Hence, there must be enough storage density and/or productivity improvement over cart and tote picking to justify the investment. Also, because vertical travel is slow compared to horizontal travel, typical picking rates in man-aboard operations range between 40 and 250 lines per person-hour. The range is large because there is a wide variety of operating schemes for man-aboard systems. Man-aboard systems are typically appropriate for slow-moving items where space is fairly expensive.
Workforce automation
In the second decade of the 2000s, the first
robotic
Robotics is the interdisciplinary study and practice of the design, construction, operation, and use of robots.
Within mechanical engineering, robotics is the design and construction of the physical structures of robots, while in computer s ...
models appeared on the market equipped with upper and lower limbs (rather than a trolley with a mechanical arm),
radar
Radar is a system that uses radio waves to determine the distance ('' ranging''), direction ( azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track ...
/
computer vision
Computer vision tasks include methods for image sensor, acquiring, Image processing, processing, Image analysis, analyzing, and understanding digital images, and extraction of high-dimensional data from the real world in order to produce numerical ...
or
sensors
A sensor is often defined as a device that receives and responds to a signal or stimulus. The stimulus is the quantity, property, or condition that is sensed and converted into electrical signal.
In the broadest definition, a sensor is a devi ...
, and capable of recognizing the products, carrying out loading and unloading operations from the truck/shelves/
forklifts, positioning the load units on the shelves, handling and
picking of the order.
See also
*
Automation
Automation describes a wide range of technologies that reduce human intervention in processes, mainly by predetermining decision criteria, subprocess relationships, and related actions, as well as embodying those predeterminations in machine ...
*
Artificial intelligence
Artificial intelligence (AI) is the capability of computer, computational systems to perform tasks typically associated with human intelligence, such as learning, reasoning, problem-solving, perception, and decision-making. It is a field of re ...
*
Actionable information logistics
*
Autonomous logistics
*
Inventory management software
*
Voice-directed warehousing
*
Warehouse
A warehouse is a building for storing goods. Warehouses are used by manufacturers, importers, exporters, wholesalers, transport businesses, customs, etc. They are usually large plain buildings in industrial parks on the rural–urban fringe, out ...
*
Automated guided vehicle
An automated guided vehicle (AGV), different from an autonomous mobile robot (AMR), is a portable robot that follows along marked long lines or wires on the floor, or uses radio waves, vision cameras, magnets, or lasers for navigation. They ar ...
References
Further reading
* Frazelle, E. (2001), World-class Warehousing and Material Handling, McGraw-Hill, New York, NY.
*
External links
* {{Commons category-inline, Automated storage and retrieval systems
Library automation
Warehouses
Automation