Automated storage and retrieval system

Robotic warehouse for physical objects

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.

An effective automated storage and retrieval system provides several benefits for supply chain management. An efficient AS/RS system helps companies cut expenses by minimizing the amount of unnecessary parts and products in storage, and improving organization of the contents of a warehouse. Due to automated processes, it also allows for more storage space due to high density storage, narrower aisles, etc. Automation reduces labor costs while lowering workforce requirements and increasing safety. Modeling and managing the logical representation of the physical storage facilities (e. g. racking, etc.). For example, if certain products are often sold together or are more popular than others, those products can be grouped together or placed near the delivery area to speed up the process of picking, packing and shipping to customers. Enabling a seamless link to order processing and logistics management in order to pick, pack, and ship product out of the facility. Tracking where products are stocked, which suppliers they come from, and the length of time they are stored. By analyzing such data, companies can control inventory levels and maximize the use of warehouse space. Furthermore, firms are more prepared for the demands and supplies of the market, especially during special circumstances such as a peak season on a particular month. Through the reports generated by an AS/RS system, firms are also able to gather important data that may be put in a model for it to be analyzed.

Vertical lift modules (VLMs) can be built to a height to match the available overhead space in a facility. Multiple units can be placed in 'pods' whereby an operator can retrieve items from one unit while the other units are moving. Variants include width, height, load, speed and a control system. The VLM is a board controlled automated vertical lift module. Inventory within the VLM is stored on front and rear tray locations or rails. When a tray is requested, either by entering a tray number in the built in control pad or by requesting a part through software, an extractor travels vertically between the two columns of trays and pulls the requested tray from its location and brings it to an access point. The operator then picks or replenishes stock and the tray is returned to its home upon confirmation. VLM systems are sold in numerous configurations, which could be applied in different industries, logistics, as well as office settings. The VLM systems could be customized to fully utilize the height of the facility, even through multiple floors. With the capability of multiple access openings on different floors, a VLM system is able to provide an innovative storage and retrieval solution. The rapid movement of the extractor, as well as inventory management software, can dramatically increase the efficiency of the picking process. This occurs by simultaneously retrieving and storing trays in multiple units. Unlike large AS/RS systems, which require a complete overhaul of the warehouse or production line, the vertical lift modules are modularized, which can be easily integrated into the existing system, or to be rolled out in gradually over different phases. Most common applications include: MRO, order picking, consolidation, kitting, parts handling, buffering, inventory storage, WIP, buffer storage, and many more. VLMs provide floor space savings, increased labor productivity and picking accuracy, improved worker ergonomics, and controlled process. Most VLMs offer dynamic space storage which measures the tray every time it is returned to the unit to optimize space, safety features and some offer tilt tray delivery for increased ergonomic accessibility, and laser pointers which indicate the exact item to be picked on each tray.

A horizontal carousel is a series of bins which revolve on an oval track. Every bin has shelves which are adjustable to and can be configured for a myriad of standard and special applications. An operator simply inputs a bin number, part number or cell location and the carousel will rotate via the shortest path. Multiple horizontal carousels integrated with pick to light technology and inventory management software (a pod of carousels) are used for order fulfillment. A wave of orders is sent to the pod. A group of orders is selected to create a batch. The operator simply follows the lights and pick round robin from the carousels and place items in a batch station behind them. Each carousel pre positions and rotates when picked. By applying the "product to person" principle, operators do not have to move from their position to prepare the order. When the batch is complete, a new batch is inducted and the process repeated until the wave is complete. Horizontal carousels can save up to 75% of floorspace, increase productivity by 2/3, accuracy levels to 99.9+% levels and throughput up to 750 lines per hour/operator. Horizontal carousel systems generally outperform robotic systems for a fraction of the cost. Horizontal carousels are the most cost effective AS/RS system available. Robotic Inserter/Extractor devices can also 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 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.

Installed applications of this technology can be wide ranging. In some libraries, such as at University of Nevada, Reno 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.

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.

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 40 feet (12 m) 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.

In the second decade of the 2000s, the first robotic models appeared on the market equipped with upper and lower limbs (rather than a trolley with a mechanical arm), radar/computer vision or sensors, 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.