Daifuku developed the first automated storage and retrieval system (AS/RS) in Japan in 1966. The objectives for developing this system included achieving workload reductions and cost savings through (1) the effective use of land, (2) improvements in storage efficiency, (3) personnel saving and labor saving in warehouse work, and (4) improvements in management levels. At the time, single-story warehouses were standard type for warehouses. Logistics capabilities were not as advanced as current levels because loading, unloading, and storage work mostly consisted of manual labor, and stored goods were managed through ledgers and slips. The automated warehouse that emerged under these circumstances was a revolutionary logistics technology innovation that overturned the traditional concept of warehousing.
About forty years since the birth of this technology, automated warehouses have now become more high-capacity and high-performance through the expansion of models, including stacker cranes and peripheral equipment, while its purposes and industries and businesses delivered to have rapidly grown. Here we will introduce our automated warehouse market and technology developments, as well as future trends.
1970s: Spread of Systems Boosted by Increasing Adoption of Computer Technologies
As suggested by its name, automated storage and retrieval systems (AS/RS) are systems that allow warehouses to become three-dimensional and automated, and they had mostly been used for storing finished goods and raw-material by manufacturers until the beginning of the 1970s. Furthermore, because automated warehouses were not necessarily low-cost at the time and the breakeven level was high, customers mainly consisted of large companies.
In 1966, we delivered the Rackbuil System (rack-supported building with an AS/RS, hereinafter "RB"), which was operated onboard, to the Electric Motor Department of Matsushita Electric Industry (at that time) as the the first automated warehouse in Japan (photo 1). In addition, we commenced with unmanned operations of a stacker crane called Rack Master (RM) that enabled automated warehouse storage locations to be managed based on X, Y, and Z coordinates and could be operated easily with a computer. In 1969, we delivered the first fully automated RB using computer control in Japan to the Nobeoka Plant of Asahi Chemical Industry Co., Ltd.
As a result of the possibility of controlling automated warehouses by computer, the accuracy of inventory management was improved, as inventory management could be done simultaneously with the retrieval and storage of materials. As a result, a sudden expansion of the industries adopting these systems began. For example, some of the largest automated warehouses in the world were delivered to the Kasuga Plant of Toyota Motor Corporation and the Sagamihara Parts Center of Nissan Motor Co., Ltd., which are both auto service parts centers that manage tens of thousands of items. In addition, automated warehouses were also adopted at pharmaceutical companies, mainly for the purpose of strengthening the accuracy of inventory management and storage and retrieval management.
From the mid 1970s, the effectiveness of automated warehouses began to become recognized in the market and demand grew for automated warehouses that were more economic and lower-priced than building-style systems. In response to these needs, we developed and commenced the sales of the technical standard-compliant unit load AS/RS and the superfast mini load AS/RS.
1980s: Adoption in a Wide Range of Fields
In the 1980s, capital investments in the manufacturing industry were active as the competitiveness of Japanese industrial products began to surpass those from Europe and North America. The applications of AS/RS also expanded from the past focus on finished goods storage to include production sites, including those electricity, electronics, and precision machinery manufacturing. These warehouses were used as equipment allowing interbay and intrabay initial setup, sorting with parts storage and supply capabilities, and buffer capabilities enabling 24-hour-a-day operation. Against this backdrop, interbay and intrabay automatic warehouses and automatic guided vehicles (AGV) were developed, along with production systems integrated all the way to production facilities with computers. We delivered our advanced factory automation systems to many leading companies that included Fanuc Corporation, Fujitsu Limited, and Makino Milling Machine Co., Ltd. (Photo 3). Strong demand has continued to this day for flexible manufacturing systems for machining center developed during this period.
Meanwhile, finished goods storage systems were called on to fulfill a distribution center function. Many centers were built with higher levels of automation through combinations of AS/RS and various peripheral equipment that had been systemized. We delivered advanced distribution center systems to many companies including Toppan Forms Co., Ltd., Sangetsu Co., Ltd., and Yamanouchi Pharmaceutical Co., Ltd. At these distribution centers, the HQ information system and logistics center systems are connected by a dedicated line in an effort to achieve reductions in delivery lead time, delivery accuracy, and inventory management accuracy. In addition, it was around this time that we began exporting AS/RSs overseas, accompanying the global expansion of the Japanese manufacturing industry, which continues to this day.
Accompanying the combination of the economic environment and the lack of manpower from the mid-1980s, AS/RSs, which had mainly been delivered to large corporations, also became adopted by small and medium-sized manufacturers, and the market expanded at a rapid pace as a result. The spread of personal computers began to keep pace with these developments, and developing relatively inexpensive inventory management systems using personal computers and software packages became possible. With these developments, small-scale AS/RSs commonly conducted inventory management in sync with cargo storage and retrieval through computer control.
1990s: Emergence of Various High Capacity Systems
From the late 1980s and early 1990s, industries outside of manufacturing began adopting automated warehouses, including the agriculture, wholesale and retail industry, warehousing, bank, insurance, and public agencies. These industries did not have much previous experience with logistics automation, which led to a further expansion in the scope of the market. For example, in the field of agriculture, automated warehouses were used as depositories for unpolished rice, fruit refrigeration, cold refrigeration of pre-shipment vegetables, and mushroom culturing, as well as as sorting and shipping equipment at sorting facilities for fruits and vegetables.
In the latter half of the 1990s, systems began to be adopted at stages of distribution closer to end users. In the warehouse industry and wholesale and retail industry, automated warehouses were used as import bases for consumer goods, which was increasing with deflation, and within logistics center in order to fulfill supply chain management (SCM). At these distribution centers, mini load AS/RS, which are capable of handling cargo of a variety of shapes and sizes, were also adopted for purposes that differed from traditional storage functions, such as a high-capacity pre-shipping alignment or as initial setup for picking. At Daifuku we have developed higher capacity mini load AS/RS and expansion of transfer equipment variations to meet these needs. Furthermore, in 2002, we developed the high-capacity mini load AS/RS Magic Sorting System (MIII), which reduced the cycle time by about one-half compared to previous AS/RS, making it possible for mini load AS/RS to support the freight handling speed of transit-type distribution centers.
In this manner, there has been an need meet demands for functions that match significant changes in the logistics environment. Also, with the ongoing aging of automated equipment that had been constructed in the 1970s to 1980s, there has been a demand to renew equipment.
Automated Warehouses for Special Environments
While the initial refrigerated storage AS/RSs were constructed during a brief period in the 1970s, construction was suspended due to the fact that profitability was low. However, profitability was improved with the progress of refrigeration technologies and changes in the social and logistics environment, and, as a result, construction demand grew for automated warehouses for industries, including food wholesaling and marine products processing, from the 1990s.
For hazardous goods warehouses, full-fledged construction of automated warehouses, with building areas of up to 1,000 m2 and height up to 20m, became possible with the partial revision and enforcement of Japan's Fire Defense Law in 1990. It also became possible to construct many rack-supported building AS/RS, with an emphasis on storage capabilities, in this field for which small-scale unit-type AS/RS (interbay warehouses) had been mainstream in the past.
In semiconductor manufacturing, demand for high levels of cleanness within the manufacturing process grew with the increase in the level of integration . As workers were the largest source of dust within cleanrooms, it was necessary to adopt unmanned operations for interbay transport and interbay buffers. The cleanroom AS/RS Clean Stocker (CLS) was developed as an interbay buffer facility. Currently, many CLS have been adopted at work sites in countries around the world, including those of major semiconductor manufacturers. In addition, these technologies have been used in production lines for LCD and PDP.
Developments in Technologies
RM: Diverse Variations in Terms of Applications and Functions
Because the initial RM drive unit consisted of a combination of a pole change motor and sliding joint, its speed was limited to a horizontal traveling speed of 90m per minute and 20m per minute for vertical speed, with a processing capacity of 20 to 30 pallets per hour. A transition was made to DC motors at the end of the 1970s and inverter control in the 1980s, in an aim to achieve faster speed. Currently, the horizontal traveling speed has been improved to 200m per minute, the vertical speed has been improved to 100m per minute, and processing capacity has been improved to 60 pallets per hour.
RM variations have been expanded in accordance with use purposes and functions. Currently, there is a diverse range of types that include traverser-type systems that use a single RM for multiple passages, double-deep type systems that store two in racks that are two-deep, and twin shuttle-fork types that carry two loads. For mini-load RM transfer equipment, various models were developed, including fork-type clamp models and lead-in models using side belts, to enable the direct handling of various sizes of carton cases, accompanying the expansion of customers to include tertiary industries.
RM operation methods include boarded operation, numerical keypad or location number cards, and computer control. Currently, computer control has been adopted for most AS/RSs. However, in cases which the items stored are limited, such as with molds, the number of items is low, and operations are conducted within a fixed location, operations are still conducted using numerical keypad or location number card setting due to the ease of use. Moreover, boarded operation is only used for extremely limited systems in Japan.
More Advanced Control Through Built-in Microcomputers
While a relay circuit was used at the initial stage of development, panels began using transistors soon afterwards, and a shift was made to panels with built-in microcomputers in the late 1970s. While moving cables were initially used to convey signals between the RM unit and the ground, inductive radio was adopted from the second half of the 1970s and was then subsequently changed to optical transmission in the 1980s.
In the 1980s, the performance of microcomputers improved and costs were reduced, making a significant contribution to higher performance RMs. For example, for the RM stop position control method, in order to replace detection plates, position learning control (patent held by Daifuku) was developed in which the actual rack position is detected in order to automatically determine the stop position for each rack. This technology has both improved the reliability of automated warehouses and reduced adjustment periods in the field. From the late 1980s, control circuit packages were adopted for the control of automated warehouse systems accompanying the shift to decentralized control from concentrated control including peripheral equipment. This made it possible to achieve improvements in quality and the ease of maintenance, as well as reductions in lead times.
As the market for automated warehouses expanded from a focus on the manufacturing industry to include the primary industry and tertiary industry, the number of client companies without maintenance personnel increased, making the early detection of and early recovery more critical. In response to these needs, Daifuku developed the 9X Model delivery control model in 1991, which is standardly equipped with a graphic display monitoring system using menus, an error log management system, and a remote monitoring system using communication lines in advance of other competitors in the industry. At the same time, an internal system support center (SSC) was opened to provide systems servicing 24 hours a day, 365 days a year online, to support users that systems have been delivered to.
Enhancement of Peripheral Equipment, such as STVs and Robots
Initially, most peripheral equipment for automated warehouses were composed of conveyor lines. During the 1980s, external drive shuttle carts with a mechanical speed change mechanism were developed in an aim to improve speed and reliability of freight handling. However, performance of processing capacity, horizontal traveling speed, noise during operation, and ease of maintenance did not meet the demands of the market. In order to resolve these issues, in 1987 the high-speed, high-capacity, extremely low-noise guided Sorting Rransfer Vehicle (STV), which also has autonomous decentralized control, was developed. This enabled system standardization and improved reliability, reduced delivery time, and decreased cost. The current STV is an essential piece of peripheral equipment for AS/RS.
Picking work of cased units at distribution centers is necessary in order to support small shipments of products stored in pallet units. In the past, many cases picking work was conducted manually. As this labor-intensive work also caused back pain, there was a major need for automation at distribution centers with frequent case picking. In 1995, a case picking system that combined robots and position recognition equipment using image processing was developed in response to these needs. A high-performance system linked with AS/RS was established and delivered to clients, such as beverage manufacturers, which have high volumes of case processing.
Future Market and Technology Trends
Automated warehouses have already spread to every industry sector in Japan, so we do not expect the same level of growth as during the highest stage of development. However, automated warehouses have become an essential element for not only storage, sorting, and initial setup, but also for production facilities, and similar levels of demand can be expected to continue going forward.
On a global level, many automated warehouses have been installed in Japan and Europe. In Japan, automated warehouses are broadly used for various purposes in all industry sectors, and, as a result, there are many projects involving small automated warehouses. Meanwhile, in Europe, large-scale automated warehouses are mostly being implemented by large companies, the majority of which function as distribution centers (Photo 4). In North America, many distribution centers are composed of racks, conveyors, and forklifts, with a low adoption rate of automated warehouses. In East Asia, including China, South Korea, and Taiwan, demand of automated warehouses has grown rapidly recently in line with the pace of economic growth. In China, while automated warehouses were mostly used by foreign companies that had expanded into China in the past, pioneering local companies, such as those in the tobacco industry, have started to adopt automated warehouses, and future growth of the market, similar to that seen in Japan in the early 1970s, can be expected (Photo 5).
Automated warehouses will becoming increasingly higher in performance with more variations in accordance with use purposes and functions. Currently, the features that are generally necessary have mostly been developed. We believe that the focus going forward could include the development of maintenance-free systems that take into consideration preventive maintenance, as well as more advanced comprehensive systems that utilize scheduled simulations.
Daifuku will continue listening attentively to the demands of customers as we do our utmost to establish new, more optimal systems together with our customers.
From Daifuku News No.169 (September 2003)