We address the issue of shuffling loads in Automated Storage/Retrieval Systems (AS/RS) in this paper. The objective is to pre-sort the loads into any specified locations in order to minimize the response time of retrievals. 1D, 2D and 3D AS/RS racks have been designed in order to achieve the shuffling efficiently. The shuffling algorithms are described in detail. The response time of retrieval, the lower and upper bounds of energy consumption are also derived. Results of the analysis and numerical experiments show that the shuffling algorithms are quite efficient. / Singapore-MIT Alliance (SMA)

The role of warehouse in the value stream, plays a significant part in how well a company can satisfy the requirements of a customer. To be able to support the demand of the customers, production companies are forced to produce a bigger variety of models in the product range, which results in an increasing assortment. With an effective stock keeping, there is a potential to reduce waste and increase profitability. In the choice of warehouse-design, warehouse-operations have the opportunity of choosing between a number of different designs containing manual and automated put away.It has become common that companies are choosing a combination of automated and manual processes. With this combination of processes, the companies are faced with choices about stock locations. With the help of well developed criterias about stock locations, there is a potential to achieve a more effective put away. The purpose of the study has been formulated as ”Investigate when automation in warehouse management makes the put away process in a central warehouse more efficient”.   Through a case study on a warehouse, located in Nässjö, this report will answer the research questions regarding which of the manual and automated put away processes to use. The research questions are: Which criteria affect the decision of automated or manual put away? Based on the criteria that are raised in research question 1, when is it more efficient to store carton in AS/RS in comparison with manual picking with truck in pallet racking? The research questions wish to lift criteria as a basis for decision making and when it is more effective to use automated put away. The warehouse that this study is based on is using both automated and manual materials handling. The specific automation system that has been the basis for this study’s result is AutoStore. This report has a qualitative approach, the methods that has been used for collecting data are interviews, observations and document studies.   Dimension, process time and utilization were the three criteria that are presented in the result. Based on the pallets limit of space in the automated system, the dimension of the article is the first criteria. In addition to the article’s measurements, the articles shape and material of the package had an impact if the article would fit in the load carrier. The two put away processes include different operations that differ in how long they take to execute, which has an impact on the company's efficiency. One reason for the time consuming difference, turned out to be how the quantity affects the time for put away in AutoStore comparing with the constant time for manual put away. A time consuming operation in the process with AutoStore was the one with repacking for the systems pallet. The operation also turned out to affect the utilization rate, due to its measurement of a pallets fill rate.  The quantity of put away in combination with the dimensions of the article, affects the total utilization rate.   With the result, the aim of the study is to contribute to companies that contains a combination of warehouse-design with a basis for the decision making about stock locations.

<p>The Robotics and Automation Laboratory at Virginia Polytechnic Institute and State University contains a Flexible Machining and Assembly System (FMAS) and an Automated Storage and Retrieval System (AS/RS). These systems were developed for educational purposes to emulate a typical flexible manufacturing process in industry. The AS/RS hardware was designed and constructed in a previous project by Mark Eaglesham. His project consisted of hardware development only and did not include control system development.</p> <p> The objective of this project is to design a set of software primitives to control the AS/RS. This set of primitive control sequences for the AS/RS could be used by future students to further develop the AS/RS control system at the device control level or to integrate the AS/RS with the FMAS at the workcell control level. The set of control primitives were developed in Relay Ladder Logic (RLL) on a Texas Instruments 565 Programmable Logic Controller (PLC). The set of primitives include the following functions: initialize the system, store a pallet, retrieve a pallet, move to a specified location, and shutdown the system.</p> <p> A communications dialog was developed for command and control interaction between the PLC and the workcell control computer. This protocol includes various functions to manage the AS/RS's operations. These functions commands from the workcell controller indicating what operation is needed and response from the AS/RS indicating its status and system error messages.</p> <p> In order to test the AS/RS a program to simulate the workcell controller was developed. This project report includes a description of a test program developed using QuickC. Due to hardware difficulties, this test program was not implemented. The AS/RS primitives were tested using Texas Instrument's TISOFT RLL development and monitoring software package.</p> / Master of Engineering

Syfte – Studiens syfte är att erhålla förståelse för automatisering i distributionslager. Utifrån syftet har två frågeställningar tagits fram: [1]  Vilka faktorer bör beaktas före en automatisering? [2]  Vilka är de uppfattade för- och nackdelarna med automatisering? I studien ska syftet uppfyllas genom att besvara frågeställningarna. Det har skett med hjälp av ett fallföretag. Metod – Utifrån syftet och frågeställningarna har studien valt att tillämpa en fallstudie som metod. Det har skett med ett fallföretag som levererar reservdelar till två av världens största biltillverkare och är belagt i södra Sverige. I arbetsprocessen har abduktion använts som tillvägagångssätt för att knyta samman verklighet med teori. Vidare är rapporten av både kvalitativ och kvantitativ karaktär. Datainsamlingen omfattade intervjuer, observationer och dokumentstudier för att uppnå triangulering. Resultat – I studiens resultat besvaras frågeställningarna och syftet. Det finns vissa faktorer som bör beaktas vid en automatisering av distributionslager. Några av de faktorer som lyfts fram är return on investment (ROI), hur nuvarande lagret ska integrera med en automatisering och hur människan kommer påverkas vid en stor förändring. ROI har identifierats som avgörande om en automatisering ska implementeras eller inte. Hur det nuvarande lagret integrerar med en automatisering anses vara en faktor som bör granskas innan en implementering. Människan har också en stor påverkan vid en automatisering. Vidare presenteras uppfattande för- och nackdelarna som har identifierats i studien. Implikationer – Studien riktar in sig på ett fallföretag som distribuerar reservdelar och därmed gör studiens implikationer applicerbar på liknande företag. Studien kan användas när distributionsföretag ska införa någon typ av automatisering eller för att motivera varför en automatisering ska införas. Begränsningar – Studien omfattar endast ett fallföretag som är ett distributionslager med specifika förutsättningar. Det gör att studiens resultat måste bedömas med en viss försiktighet i sin generaliserbarhet. Därtill finns det begränsningar i vilka personer som har intervjuats vilket gör att studien saknar perspektiv från den operativa kärnan. / Purpose – The purpose of this study is to gain understanding for automation in a distribution center. Based on the purpose, two research questions have been stated: [1]   Which factors should be considered before automation? [2]   What are the perceived advantages and disadvantages of automation? In the study the purpose will be answered through the research questions. This will be possible because of help from the company this study was performed at. Method – Based on the purpose and research questions, the study has chosen to apply a case study as a method. This happened with a case company that delivers spare parts to two of the world’s largest car brands and it is in south Sweden. In the work process an abductive approach has been used to connect reality with the theoretical work. Furthermore, the report is of both a qualitative and quantitative nature. The data collection included interviews, observations, and document studies to achieve triangulation. Findings – The results of the study answer the questions and purpose. There are certain factors that should be considered when automating distribution centers. Some of the factors that are highlighted are return on investment (ROI), how the current warehouse should integrate with automation and how people will be affected by a major change. ROI has been identified as decisive whether an automation should take place or not. How the current warehouse integrates with an automation is considered a factor that should be reflected on before an implementation. Humans also have a great influence on automation. Perceptual advantages and disadvantages are highlighted. Implications – This study focuses on a case company that distributes spare parts and thus makes the study's implications applicable to similar companies. The study can be used when distribution companies are to introduce some type of automation or motivate why automation should be implemented. Limitations – The study covers one case company that is a distribution center with specific conditions. This means that the result of the study must be considered with certain caution in their generalizability.

This dissertation focuses on developing analytical models for automated storage and retrieval system with multiple in-the-aisle pick positions (MIAPP-AS/RS). Specifically, our first contribution develops an expected travel time model for different pick positions and different physical configurations for a random storage policy. This contribution has been accepted for publication in IIE Transactions (Ramtin & Pazour, 2014) and was the featured article in the IE Magazine (Askin & Nussbaum, 2014). The second contribution addresses an important design question associated with MIAPP-AS/RS, which is the assignment of items to pick positions in an MIAPP-AS/RS. This contribution has been accepted for publication in IIE Transactions (Ramtin & Pazour, 2015). Finally, the third contribution is to develop travel time models and to determine the optimal SKUs to storage locations assignment under different storage assignment polies such as dedicated and class-based storage policies for MIAPP-AS/RS. An MIAPP-AS/RS is a case-level order-fulfillment technology that enables order picking via multiple pick positions (outputs) located in the aisle. We develop expected travel time models for different operating policies and different physical configurations. These models can be used to analyze MIAPP-AS/RS throughput performance during peak and non-peak hours. Moreover, closed-form approximations are derived for the case of an infinite number of pick positions, which enable us to derive the optimal shape configuration that minimizes expected travel times. We compare our expected travel time models with a simulation model of a discrete rack, and the results validate that our models provide good estimates. Finally, we conduct a numerical experiment to illustrate the trade-offs between performance of operating policies and design configurations. We find that MIAPP-AS/RS with a dual picking floor and input point is a robust configuration because a single command operating policy has comparable throughput performance to a dual command operating policy. As a second contribution, we study the impact of selecting different pick position assignments on system throughput, as well as system design trade-offs that occur when MIAPP-AS/RS is running under different operating policies and different demand profiles. We study the impact of product to pick position assignments on the expected throughput for different operating policies, demand profiles, and shape factors. We develop efficient algorithms of complexity O(nlog(n)) that provide the assignment that minimizes the expected travel time. Also, for different operating policies, shape configurations, and demand curves, we explore the structure of the optimal assignment of products to pick positions and quantify the difference between using a simple, practical assignment policy versus the optimal assignment. Finally, we derive closed-form analytical travel time models by approximating the optimal assignment's expected travel time using continuous demand curves and assuming an infinite number of pick positions in the aisle. We illustrate that these continuous models work well in estimating the travel time of a discrete rack and use them to find optimal design configurations. As the third and final contribution, we study the impact of dedicated and class-based storage policy on the performance of MIAPP-AS/RS. We develop mathematical optimization models to minimize the travel time of the crane by changing the assignment of the SKUs to pick positions and storage locations simultaneously. We develop a more tractable solution approach by applying a Benders decomposition approach, as well as an accelerated procedure for the Benders algorithm. We observe high degeneracy for the optimal solution when we use chebyshev metric to calculate the distances. As the result of this degeneracy, we realize that the assignment of SKUs to pick positions does not impact the optimal solution. We also develop closed-form travel time models for MIAPP-AS/RS under a class-based storage policy.

In this thesis a custom embedded system and control software developed for an Automated Storage and Retrieval System (AS/RS) which is based on the Computer Integrated Manufacturing Laboratory (CIMLAB) located in the Department of Mechanical Engineering, Middle East Technical University. Primary objective of this study is AS/RSs related control rules can be applicable to the current physical system. The secondary objective is determined as developing the control system in a flexible way that allows adding new equipments to the system and configuring parts of the system. Two types of control board are manufactured and also boards&rsquo / firmware and computer software are developed. These two boards communicate with computer one at a time. Some AS/RS related control rules are implemented at the control software. According to these rules the control software assigns tasks to the related board. Also the control software records necessary information in order to measure the performance of the AS/RS. Several control rules as storage assignment, dwell point and sequencing of storage and retrieval order rules are applicable to the AS/RS without need for low level programming. Because of the physical limitation, batching rules cannot be applied to the current system. Also a graphical user interface is developed for using the system easily and observing the real time status of the system equipments. Two experiments are designed and run in order to show flexibility of the control system. Different control rules applied to each of the experiment. Experiment results put forth the control system was quite successful in meeting the objectives.

Titel: Lagerhantering och Automated Storage and Retrieval System (AS/RS) – En flerfallstudie om Automated Storage and Retrieval systems för- och nackdelar för en kostnadseffektiv lagerhantering Kurs: Examensarbete i Controller för Civilekonomprogrammet, 30 hp (4FE18E) Lärosäte: Ekonomihögskolan vid Linnéuniversitetet i Växjö Författare: Anton Lindh Inledning: Lagerverksamheten har fått en ökad betydelse för företags framgång. Designen på moderna lager har en stor påverkan på investering- och driftkostnad. Vidare sätter e-handelns ökning samt kunders krav press på lagerverksamheter i form av ökat behov av lagerutrymme, behov av alternativ för att hålla nere höga personalkostnader samt snabba leveranser. Automated Storage and Retrieval systems (AS/RS) är ett automatiserat lagersystem som ökar stadigt i användning hos stora företag. I uppsatsen görs försök att undersöka hur för- och nackdelarna påverkar kostnadseffektiviteten av lagerhanteringen och lagerverksamheten. Även huvudtyperna av AS/R system samt AS/R systemets komponenter undersöks för att ge en möjlig förklaring till hur dessa påverkar utfallet av systemets kostnadseffektivitet Syfte: Syftet med uppsatsen är att kartlägga de för- och nackdelar som AS/R system bidrar till lagerhanteringen samt hur för- och nackdelarna kan påverka hur kostnadseffektiv lagerhantering blir. En del av syftet med att besvara fråga 1 och 2 är att kunna vidare djupdyka i och analysera de olika typer och komponenter ett AS/RS består av och se hur dem specifikt kan bidra till slutsatserna av fråga 2. Besvarandet av frågorna ska bidra till ökadförståelse om hur AS/RS på olika sätt kan hjälpa (eller stjälpa) lagerverksamheten och lagerhanteringen att bli mer kostnadseffektiv hos företagMetod: I uppsatsen har en flerfallstudie genomförts med 3 företag som tillsammans har 4 AS/R system. Den empiriska materialinsamlingen skedde genom semistrukturerade intervjuer. Slutsats: Slutsatserna belyser flera för- och nackdelar. Framstående slutsatser inkluderar nackdelar såsom att AS/R system har höga initiala investeringskostnader samt flera flexibilitetsproblem som kan hindra en kostnadseffektiv lagerhantering. Å andra sidan har flera fördelar belysts såsom hög genomströmningskapacitet på grund av underlättande av rutiner och högre produktivitet tillsammans med lägre personalkostnader och minskad ytanvändning. Två analytiska modeller är även presenterade för slutsatserna kring AS/R systemens huvudtyper samt komponenter och deras påverkan på en kostnadseffektiv lagerhantering.

Title: Improved productivity in an automated ”pick and pack” process - Förbättrad produktivitet i en automatiserad plock- och packningsprocess – A case study at Staples Sweden AB Authors: Emelie Hjärtåker &amp; Lovisa Berg Tutor: Petra Andersson Examiner: Helena Forslund Background: There is a lot of research within automated warehouse and especially about storage layout but no research that are including the functions within the process and how they beneficially should interact with each other. At the same time companies strives for improved productivity which might be easier to reach with a process orientated view rather than a function based view. Even if many companies constantly strives for an improved productivity there is often potential for improvements where an amended work procedure may be the answer. Purpose: The study’s purpose is to describe Staples current productivity and identify waste within the automated ”pick and pack” process with help of a process map.  With the identified wastes improvements will be suggested to reach productivity improvements. At least the study to find to which extent a buffer function can improve productivity in an automated ”pick and pack” process. Method: This study is a case study at Staples. Data has been collected by unstructured and semi structured interviews and participant observations. The aim of the study is to purpose improvements within productivity by improvements suggestions and to show how productivity potential may increase by changing the work procedure and by view the process as one mutual process by a test, measurements and calculations. Conclusions: A buffer function can with changes in the work procedure conduct to productivity improvements. The authors states that companies need to view the process productivity as a common goal and measure where the functions together work to achieve the same main goal. By analyzing patterns within purchase and packaging a company can with the help of measurements see which work procedure beneficially the automated ”pick and pack” process productivity most. Furthermore the work procedure needs to be easily be communicated out to the staff with encouragements for the implementation to be successful. / Titel: Förbättrad produktivitet i en automatiserad plock- och packningsprocess - En fallstudie på Staples Sweden AB Författare: Emelie Hjärtåker &amp; Lovisa Berg Handledare: Petra Andersson Examinator: Helena Forslund Bakgrund: Det finns mycket forskning inom automatiserade lager med fokusering på lager och layout men ingen som visar på hur automatiserad lager förhåller sig till närliggande funktionerna. Många företag strävar idag efter ökad produktivitet vilket kan bli enklare att uppnå med ett processorienterat synsätt istället för ett funktionsbaserat synsätt. Även om många företag ständigt strävar efter ökad produktivitet så finns det ofta potential för förbättringar och där kan ett justerat arbetssätt vara svaret. Syfte: Studiens syfte är att redogöra för Staples produktivitet och identifiera vilka slöserier som finns i den nuvarande automatiserade plock- och packningsprocessen genom en processkartläggning. Med hjälp av de identifierade slöserierna ska förbättringsförslag tas fram till hur dessa kan åtgärdas för ökad produktivitet. Avslutningsvis skall studien utföra ett test för att identifiera i vilken omfattning en försörjande funktion kan förbättra produktiviteten i en automatiserad plock- och packningsprocess. Genomförande: Studien som genomförts är en fallstudie på Staples. Data har blivit insamlat genom semistrukturerade och ostrukturerade intervjuer samt deltagande observationer. Målet med studien har varit att föreslå produktivitetsförbättringar dels genom förbättringsförslag och dels genom att visa att produktiviteten potentiellt kan öka genom att justera arbetssättet och se processen som enhetlig vilket visualiseras med hjälp av test, mätningar och beräkningar. Slutsats: En försörjande funktion kan med justering leda till förbättrad produktivitet inom en automatiserad plock- och packningsprocess. Författarna menar att företag måste behandla processens produktivitet som ett gemensamt mål och mått där funktionerna arbetar tillsammans mot samma mål. Med hjälp av att analysera köp-, förpackning och brytmönster på artiklar kan företag få fram med hjälp av mätningar vilket arbetssätt som gynnar den automatiserade plock- och packningsprocessens produktivitet mest. Vidare måste arbetssättet enkelt förmedlas ut och uppmuntras till medarbetare inom funktionen för att implementeringen ska vara möjlig.

Approved for public release; distribution in unlimited. / Future sea bases, such as the Maritime Prepositioning Force (Future), will serve as key distribution nodes and must be able to sustain forces ashore and selectively offload supplies from storerooms quickly and efficiently. Current MPF ships maximize the available cargo storage onboard and have little ability to selectively offload supplies. To make selective offload a reality, MPF(F) requires lower stowage densities and new technologies to efficiently move items, especially for those supplies needed in direct support of forces ashore. The difficult questions are how dense and in what configurations MPF(F) storerooms can be packed, and how items should be retrieved in order to selectively offload supplies and provide acceptable response time. We analyze the trade-off between storage density and mean retrieval time in a dynamic environment for different storage densities and configurations in notional storerooms aboard a future sea base. We examine two demand scenarios and two different retrieval rules to determine how each storage configuration responds to retrieval requests over time. Our results provide insight into the types of storeroom configurations that provide the best mean retrieval times and how a simple retrieval rule can significantly reduce mean retrieval time under certain demand conditions. / Lieutenant Commander, United States Navy