Automated Storage/retrieval Systems Research Articles

Wireless Access and Mobility Support for Automated Storage/Retrieval System and Logistics on Aluminum Profile

The preconditions of storage pre-schedule and real-time schedule management are wireless access and mobility support technology in aluminum profile logistic, which is vital for the automated storage/retrieval system(AS/RS) and logistics processes, such as intelligent warehousing and shipment. Understandings characters of the current wireless access technologies, applicability of networking mobility schemes, and their cooperation or compatibility with the Internet of things, decide the AS/RS and logistics structure and its whole efficiency. So the relational technologies and schemes are introduced in this paper from bottom to top according to Open System Interconnect seven layers protocols. It reveals that integration of multi-technologies was widely adopted in project implementation, which can be helpful to achieve high quality of mobile Internet access with lesser costs. Moreover, the feasibility of handover simplification and quality of service construction imply the success of schemes in design. Finally the strategic impact factors of the networking mobility support technology for AS/RS and logistics are concluded as overlapping coverage network optimization, delay tolerant network, and quality of service system based on user behavior.

Motion Planning of Two Stacker Cranes in a Large-Scale Automated Storage/Retrieval System

The authors propose a method for reducing the computational time of motion planning for stacker cranes. Most automated storage/retrieval systems (AS/RSs) are only equipped with one stacker crane. However, this is logistically challenging, and greater work efficiency in warehouses, such as those using two stacker cranes, is required. In this paper, a warehouse with two stacker cranes working simultaneously is proposed. Unlike warehouses with only one crane, trajectory planning in those with two cranes is very difficult. Since there are two cranes working together, a proper trajectory must be considered to avoid collision. However, verifying collisions is complicated and requires a considerable amount of computational time. As transport work in AS/RSs occurs randomly, motion planning cannot be conducted in advance. Planning an appropriate trajectory within a restricted duration would be a difficult task. The authors thereby address the current problem of motion planning requiring extensive calculation time. As a solution, they propose a “free-step” to simplify the procedure of collision verification and reduce the computational time. On the other hand, the authors proposed a method to reschedule the order of collision verification in order to find an appropriate trajectory in less time. By the proposed method, they reduce the calculation time to less than 1/300 of that achieved in former research.

Innovative travel time model for dual-shuttle automated storage/retrieval systems

In modern production and distribution systems, the automated storage/retrieval systems (AS/RS), high-storage level systems that reduce labor cost, required floor space and error rate, while increasing product availability, have been widely used since the 1950s. Due to the high-investment costs involved in the development of high-efficient and high-flexible automated storage systems, performance estimation of the systems is both practically and theoretically important. The authors suggest a new method to estimate the travel time of a recently emerging version of AS/RSs, the multi-shuttle systems. The proposal is based on an industrial standard established by the Federation Européenne de la Manutention (F.E.M.). In order to estimate travel times, the authors conduct a Monte Carlo simulation to determine coordinates of two additional representative points which are not given by F.E.M. Then they conduct a new Monte Carlo simulation to compare the results obtained by the method they proposed with those of previous methods and models developed in scientific literature based on Bozer and White formulations. Several real industrial applications demonstrate the validity of proposed method.

DEVELOPMENT OF AN AUTOMATED STORAGE/RETRIEVAL SYSTEM

This paper shows the mathematical model of an automated storage/retrieval system (AS/RS) based on innitial condition. We iditificate oscillation modes and kinematics displacement of system on the basis model results. With the use of the present model, the automated warehouse cranes system can be design more efficiently. Also, a AS/RS model with the control system are implemented toshow the effectiveness of the solution. This research is part of R/D research project of HCMC Department of Science and Technology to meet the demand of the manufacturing of automated warehouse in VIKYNO corporation, in particular, and in VietNam corporations, in general.

Metaheuristic based control of a flow rack automated storage retrieval system

This paper presents two metaheuristic algorithms, namely taboo search and simulated annealing, applied to the control of a flow rack automated storage retrieval system (AS/RS). These metaheuristic algorithms are developed to control the retrieval machine of the AS/RS in order to minimize the retrieval cycle time. Results of these metaheuristic algorithms are compared to classical heuristics and analytical models found in literature (Gaouar et al. in MOSIM 2006, Rabat, Maroc, avril 2006; Sari et al. in Int J Adv Manuf Technol 25:979---987, 2005; Ghomri & Sari in Conception et Production Integrees, CPI'2009, Fes, Maroc, 19---21 Octobre 2009). These heuristics were developed to control the storage and retrieval of items in the AS/RS. On the other hand, analytical models were conceived to bring a bottom line for comparison of different control techniques. To carry out this comparative study, simulations were performed on a wide range of system configurations. In order to validate metaheuristics results, a sensitive study on their parameters was achieved, and the best parameters were selected for comparative study.

Innovative framework of AS/RS path planning

Until recently, a great deal of thought in Automated Storage/Retrieval System (AS/RS) path planning has focused on algorithms, but very little attention was paid to what actually went on inside industrial settings. Traditional algorithms for Automated Guided Vehicles (AGVs) were over emphasised local optimisation that AGVs are too complicated to systematise for path forecasting in AS/RS path planning. The purpose of this study is to establish a feedback mechanism to modify AGV transport movement. An innovative AS/RS framework was inductively established throughout this study. This study used Scenario Analysis (SA) to evaluate AGVs' dynamic path for goal orientation and used the four circular steps Eliminate, Combine, Rearrange, Simplify (ECRS) to establish a feedback mechanism to modify AGV transport movement and analyse nonlinear dynamic behaviour. This study presents a conceptual framework for linking goal orientation and feedback mechanisms in AS/RS path planning.

An innovative automated storage and retrieval system for B2C e-commerce logistics

Flexible and timely warehousing activities provide a strong foundation for logistic systems. However, increasing B2C e-commerce with a variety of small internet orders may have a tremendous impact on warehousing. Automated storage/retrieval systems (AS/RSs) are a valid alternative for warehousing. Typical AS/RSs design and control problems in a static environment and cannot effectively manage parcel, small, and irregular items. This study proposes a new AS/RS that is more efficient and flexible for handling B2C e-commerce logistics. An auto-access multilevel conveying device (IMCD) with three-dimensional movement is integrated into the AS/RS. The ant colony system algorithm locates near-optimal routes for the IMCD. Typical travel distance/time measures evaluate the performance of an S/R device running on a warehouse floor. However, the performance index in this study looks at the IMCD’s travel time with three-dimensional movement in completing a batch order. To validate the new AS/RS, two simulation experiments were conducted to examine the effects of three-dimensional velocity and rack shape. Finally, this study compares a typical S/R system with the new AS/RS and makes recommendations for practical applications and further research.

A STATISTICAL MODEL FOR EXPECTED CYCLE TIME OF SP-AS/RS: AN APPLICATION OF MONTE CARLO SIMULATION

The elimination of international trade barriers, lower tariffs, and shifting centers of global manufacturing and consumption leads to new dynamics in intermodal shipping. Advanced technologies, and in particular, automated storage/retrieval systems (AS/RSs) for designing high-capacity automated container terminals, have been recently proposed as possible candidates for improving the terminal's efficiency and meeting the challenges of the future in marine transportation. In this article, the authors present an analytical statistical model for computing expected cycle time of split-platform AS/RS (SP-AS/RS), in order to reduce average handling time of this system. The accuracy of the proposed statistical model is validated by Monte Carlo simulation. The results show that the analytical model is reliable for the design and analysis of the SP-AS/RS.

Dynamic availability-oriented control of the automated storage/retrieval system. A computer integrated manufacturing perspective

Dynamic scheduling of the storage/retrieval (S/R) requests and increasing the utilization of the storage spaces, are the two common approaches to improve the efficiency of the automated storage/retrieval systems (AS/RS) in industry practice. However, the actual improvement of the AS/RS has to be justified from the perspective of computer integrated manufacturing system (CIMS) because the ultimate objective of the AS/RS is to assist the CIMS in enhancing its material handling efficiency as well as synchronizing the production. Targeting on this crucial requirement, a dynamic availability-oriented controller (DAOC) is developed in this paper to minimize the mean request fulfilment time of the AS/RS. Firstly, while considering the three types of critical dynamic constraints from the CIMS’ shop floor: the availabilities for both machines and the AS/RS, the process plan of the product, and the production schedule, DAOC is capable of determining the optimal execution sequence of the S/R requests issued from the CIMS and activating dynamic storage space consolidation commands of the AS/RS. Secondly, simulation experiments are conducted and the results show that DAOC successfully improves the S/R request control scheme of the traditional class-based assignment method and significantly outperforms four comparable approaches under various CIMS configurations.

Design and control of an AS/RS

Automated storage/retrieval systems (AS/RSs) are a combination of equipment and controls which automatically handle, store and retrieve materials (components, tools, raw material and subassemblies) with great speed and accuracy. Consequently, they are widely used in industrial companies to manage products with cost-effective utilization of time, space and equipment. This paper presents a multi-parametric dynamic model of a product-to-picker storage system with class based storage allocation of products. Thousands of what-if scenarios are simulated in order to measure the impact of alternative design and operating configurations on the expected system performance and to identify the most critical factors and combinations of factors affecting the response of the system. Class based storage proves to be a very effective way of both reducing the picking cycle time and maximizing the throughput of the system. The rapid effectiveness of visual interactive simulation (VIS) in supporting the design (redesign) and control of new (existing) warehouses emerges, responding to the need for flexibility which modern companies need in order to adapt to strongly changing operating conditions quickly.

Optimal design of rack structure with modular cell in AS/RS

In this paper, the model of AS/RS with the rack of modular cells is proposed first. In general, under the concept of unit load, Automated Storage/Retrieval Systems (AS/RS) has the rack of equally sized cells. Many authors have studied the design of AS/RS with the rack of equally sized cells. However, they are inadequate and inefficient in meeting the various sizes of customers’ demands in today's business environment. Higher utilization and flexibility of warehouse storage can be achieved by using AS/RS with the rack of modular cells. The best size of modular cell is determined as a decision variable and the effectiveness of the proposed model is also presented. The model developed in this research, is one type of AS/RS that is more flexible to the size and has higher space utilization than those of existing rack structure, could be a very useful alternative for the storage of different unit load sizes.

An analysis of the end-of-aisle order picking system: Multi-aisle served by a single order picker

This study deals with an end-of-aisle order picking system in a miniload automated storage/retrieval system (AS/RS). The system has a horse-shoe style buffer at the front end of each aisle. A conveyor system delivers the containers through the buffer positions. Earlier studies for the system assumed that an order picker serves only a single aisle. In general, however, an order picker can server two or more aisles for labor cost saving, and so this paper assume that an order picker serves a number of aisles in a predetermined order. The system can be modeled as a queueing system with a limited queue length and this paper analyzes the queueing model with supplementary variable technique to find the system's long-run behavior. Then, it proposes a simple optimization model to find an optimal buffer size. To illustrate the results, some examples are included into each chapter.

A performance estimation model for AS/RS by M/G/1 queuing system

It is quite common to adopt a static approach or computer simulation method for the performance estimation of the Automated Storage/Retrieval System (AS/RS). In most research, the authors assume that the storage/retrieval machine performs only either single command or dual command at each operation and, in addition, the type of request is known in advance, which is not adequate in the real system. In this paper, we propose a stochastic approach for the performance estimation of a unit-load AS/RS by using an M/G/1 queuing model with a single server and two queues. In particular, the steady state probability distribution of the number of storage and retrieval commands waiting in the queues is obtained in the form of transform. According to the computational comparison with the simulation, the proposed approach gives satisfactory results with very high accuracy.

Scheduling decisions in FMS using a heuristic approach

The paper deals with the multilevel scheduling decisions of a Flexible Manufacturing System (FMS) to generate realistic schedules for the efficient operation of the FMS. The primary concern of an Operations Management System (OMS) for a FMS is production scheduling, Material Handling System (MHS) scheduling, Automated Storage/Retrieval System (AS/RS) operation and control and tool management. Scheduling is a critical issue and determines how efficiently the production resources are utilised and how the selected parts are affected in the system. In this paper, the integrated scheduling of FMS, namely, the production scheduling conforming with the MHS scheduling, is addressed. An enumerative heuristic is used, namely Giffler and Thompson, which is an evolutionary combining a Genetic Algorithm (GA) and a stochastic neighborhood search technique using a Simulated Annealing (SA) algorithm is employed.

An integrated model for the design of end-of-aisle order picking system and the determination of unit load sizes of AGVs

In this paper, we deal with an assembly line production system in which an automated guided vehicle (AGV) delivers parts to each workstation of assembly lines from a miniload automated storage/retrieval system (AS/RS). Each assembly production line is characterized by a sequence of workstations linked together for the production of a given type of product. We consider simultaneously the design problem of miniload AS/RS and the problem of determining a unit load size of the AGV. First, a non-linear mathematical model is formulated under a proposed AGV dispatching policy. And then, we determine an appropriate sequence of lines of the vehicle visits. Finally, based on the characteristics of the objective function and feasible region of the decision variables, a heuristic solution procedure is developed to find a near optimal solution. To examine the validity of the model, an example problem is solved.

Analytic expressions for the optimal dwell point in an automated storage/retrieval system

We consider the problem of selecting the dwell point position of the storage/retrieval (S/R) machine in an automated storage/retrieval system (AS/RS). This is the position where the S/R machine resides when the system is idle. Our objective is to minimize the expected travel time to the position of the next operation. We present analytic expressions for the randomized and class-based storage policies. The expressions may be incorporated in a design framework for estimating the system performance.

The impact of an automated storage and retrieval system on public services

In June 1998, the Bruce T. Halle Library opened on Eastern Michigan University’s campus and began using an automated storage and retrieval system for low‐use books and periodicals. Approximately one third of the library’s total collection was placed into this storage system, freeing floor space for many new activities in the library. This system, linked to the library’s online catalog, could retrieve items requested by a patron in less than ten minutes. While the Automated storage/retrieval systems (AS/RS) performed well, other start‐up problems of a new building and public perceptions of the AS/RS made its introduction a challenge. Planning, implementation, and public reaction and acceptance are discussed.

Effects of relocation to AS/RS storage location policy with production quantity variation

Most research on AS/RS (Automated Storage & Retrieval Systems) operation policy concludes that class-based storage policy has better performance than random storage policy. This result would be obtained if the system performance is evaluated with a fixed production plan. However, the production quantity of each item can not be kept at the same level at all times. The effect of production quantity variation per product between 10 and 80% is studied with random storage policy, 2 class-based, and 3 class-based storage policies with/without relocations to find acceptable ranges of variations. A typical AS/RS model is developed using GPSS/PC to be used for the evaluations. An applicable operation policy could be selected based on the degrees of production plan variation or a necessary variation point for re-location could be determined with the current policy.

A BOM Oriented Class-Based Storage Assignment in an Automated Storage/Retrieval System

A storage assignment policy based on the needs of manufacturing operations can increase not only the performance of the automated storage/retrieval system (AS/RS) but also the performance of the production system. In general, the needs of manufacturing operations are embedded in material attributes, and the bill of material (BOM) is the best source to link material attributes. By employing the BOM as the backbone structure of a production system, a CIM system can be thoroughly integrated. Past work has identified a class-based assignment method for an AS/RS as a reasonable and efficient storage assignment policy. This study presents a BOM oriented class-based storage assignment method for an AS/RS. The proposed method possesses not only the advantage of a class-based storage method, but also the feasibility to integrate an AS/RS into a CIM system. To illustrate the effectiveness of the proposed method, a case study is presented. A random storage assignment method is also employed to obtain the solution for the illustrative example. The results are used to compare with those obtained by the proposed method. From the results of comparative studies, the proposed BOM-oriented class-based AS/RS assignment method is shown to be efficient.

Optimisation of man‐on‐board automated storage/retrieval systems

This study is concerned with evaluating the performance of different storage policies and tour construction procedures for multi‐command picking using automated storage‐retrieval systems (AS/RS). The AS/RS machine travel time for each storage policy is derived as a function of the shape of the storage area, the number of picking points and the sequencing algorithm used. The combination of these variables yields various solutions to the problem, thus providing a useful guide in designing effective picking systems. The average travel time of the AS/RS in each configuration is calculated by computer simulation in a full factorial experimental design. A subset of the results derived from this study has been successfully implemented in a case study, involving the BMW AG Italy spare parts distribution warehouse.