RFID-based information integration in manufacturing-Op RFID gebaseerde informatie integratie in fabricage

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Delft University of Technology

FACULTY MECHANICAL, MARITIME AND MATERIALS ENGINEERING

Department Marine and Transport Technology Mekelweg 2 2628 CD Delft the Netherlands Phone +31 (0)15-2782889 Fax +31 (0)15-2781397 www.mtt.tudelft.nl

This report consists of 52 pages and 0 appendices. It may only be reproduced literally and as a whole. For commercial purposes only with written authorization of Delft University of Technology. Requests for consult are only taken into consideration under the condition that the applicant denies all legal rights on liabilities concerning

Specialization: Transport Engineering and Logistics

Report number: 2014.TEL.7854

Title:

RFID-based information

integration in manufacturing

Author:

S. van den Brand

Title (in Dutch) Op RFID gebaseerde informatie integratie in fabricage

Assignment: literature Confidential: no

Supervisor: Dr. ir. Y. Pang

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FACULTY OF MECHANICAL, MARITIME AND MATERIALS ENGINEERING

Department of Marine and Transport Technology Mekelweg 2 2628 CD Delft the Netherlands Phone +31 (0)15-2782889 Fax +31 (0)15-2781397 www.mtt.tudelft.nl

Student: S. van den Brand Assignment type: Literature Assignment Supervisor: Dr. ir. Y.Pang Report number: 2014.TEL.7854 Specialization: TEL Confidential: No

Creditpoints (EC): 10

Subject: RFID-based information integration systems in manufacturing

RFID technology has been recognized as a decent way in the domain of Internet of Things. It has been extensively used for various purposes including manufacturing and supply chain management, tracing and tracking objects and persons, security and safety, etc. In industrial applications, its low-cost and fast assembly brings a revolutionary way to monitor and control manufacturing processes with optimized efficiency.

Due to the limited storage capacity and computation power of RFID tags, the information derived from RFID systems needs to be integrated to a central section or an existing information infrastructure for unified management. At present, diverse information management systems and architectures are used in managing manufacturing processes. This literature assignment is to provide a survey of RFID-based information integration solutions in manufacturing. After defining the scope of manufacturing to be studied in this assignment, the research should cover the following:

• to review RFID technology and the applications of RFID in manufacturing;

• to survey existing information management architectures or infrastructures which integrate the information captured by RFID;

• to analyze the feasibility and suitability of the architectures with respect to manufacturing management;

o to investigate in which way the information derived from RFID should be integrated into the manufacturing management process, taking account of the fact that different organizations and structures of the information systems will result in different data utilization rates.

This report should be arranged in such a way that all data is structurally presented in graphs, tables, and lists with belonging descriptions and explanations in text.

The report should comply with the guidelines of the section. Details can be found on the website.

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Delft

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Summary

Current market demands have encouraged manufacturers to operate agile, while maintaining high product quality, low prices and fast delivery. This is especially viable for complex manufacturing, as it often works with Just-In-Time delivery and lean strategies. In order to fulfil this demand, manufacturing companies rely on fast interaction which is enabled by accurate and real-time information on manufacturing processes. The generation of fast and accurate data is especially valuable for tracking and tracing activities. Although this information is often gained by bar code scanning, Radio Frequency IDentification technology (RFID) is put forward as the new technology to facilitate fast and accurate data sharing. Since RFID tags still have a limited storage capacity and generate a lot of data, an information integration solution is required. This report intends to give an overview of information integration solutions for tracking and tracing activities in complex manufacturing.

A RFID system consists of tags, readers and a back-end system to link and handle the information generated by tags and readers. As a tag passes within the range of a reader, it will automatically send the information it stores to the reader. The reader, in its turn, may pass on the information to the back-end system or use it itself. RFID is suitable for tracking and tracing in complex manufacturing since it, among others, functions automatically, can store information, does not require a line of sight and can read multiple tags simultaneously. In order to enable tracking and tracing activities, a system has to integrate the information of multiple readers to retrieve the path of a certain tag. Tags have to be placed on the products, while readers are placed on resources and inventories to retrieve the location of the product. Several schemes for connecting the hardware (called architecture) are presented.

A basic architecture consist of three layers. At first, there is a layer which consists of readers and tags. Secondly, there is a layer with the enterprise application. Finally, the middle layer ensures filtering of data, planning and scheduling activities and tracking and tracing activities. Communication between the layers and components may occur wireless with internet connection but also with Ethernet or USB cables.

Current developments in system architectures show three trends:

• Distributed control: This is also called agent based manufacturing. An agent can be a machine, but also an entire production line. The data generated by RFID is filtered, managed and handled by the agent. The agents work holonic and can communicate which each other and therefore, they can find an optimal solution for any problem together.

• Cloud computing: Here, the information generated by RFID is stored on the internet, in a cloud. The data generated by RFID is stored in the cloud, clients may access the data here via internet connection. • Internet of Things: Within the internet of things, the intention is to connect and control all objects in the world via internet, without human input. RFID tags can enable the data generation within the Internet of Things and are often seen as the building blocks. As this system is still largely in the conceptual phase, no definite architecture exists yet.

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RFID implementations are problem-specific and are all one-of-a-kind. The performed feasibility study shows that basic architectures are easy usable for small implementations, however become complex and rigid for large solutions. an advantage of all recently developed solutions is that it they are easily scalable. Of the recent developments, cloud computing shows the biggest potential in cost reduction and compatibility. Distributed control promises improvements in reliability and robustness. The Internet of Things is still strongly under development but is assumed to become a combination between agent-based and cloud computing, thereby having the possibility to benefit from both advantages.

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1 Introduction

In recent years, globalization and increased customers’ influence has encouraged manufacturing enterprises to create new products at a faster pace with lower prices, higher quality and faster delivery [1]. To gain a competitive advantage in today’s turbulent markets, a manufacturing enterprise must operate flexible, agile and reconfigurable. Manufacturing management theories as total quality management, supply chain management and lean manufacturing have therefore been emerging rapidly [2].

The performance of a manufacturing company relies on, among other things, interaction between business functions, stakeholders, partners and customers within and outside of the company [2]. In order to make decisions on a strategic, tactical and operational level throughout the supply chain, high-quality information on manufacturing processes is required [2]. Many companies nowadays realize that a competitive advantage can be gained by accurate and real-time information [3].

Information technology is used to generate data and convert this data into information [4]. These technolo-gies include, for example, bar code systems, smart cards and Radio Frequency IDentification (RFID). In the past decade, RFID has been put forward as a technology to facilitate information gathering in manufacturing [3]. RFID readers use radio signals to identify a RFID tag, therefore not requiring a line of sight or human intervention. The RFID tags consist of a small antenna to send and receive radio waves, and a small chip to store information [5].

Compared to traditional bar code systems, RFID systems can increase the amount of data captured, enable tracking and tracing activities and provide data faster, more accurate and in real time [4]. RFID is better applicable for manufacturing applications since the tags are not influenced by grease or dirt, do not require a line of sight or human intervention to be read and readers can read multiple tags at the same time [6].

The RFID tags and readers are however only a part of the overall information system. RFID tags generally have limited storage capacity and computational power. Therefore the information generated by the tags needs to be handled, integrated and stored elsewhere [6]. The basics of these information integration solutions are always the same [6]. RFID readers sent the information they collect from tags to a central information fusion layer, where the data is filtered, handled and stored. From here on the data is used by enterprise applications as Enterprise Resource Planning (ERP). In extension of the basic structure, multiple ways of information integration have been proposed to facilitate the handling of RFID generated information in manufacturing, each with different advantages and applications. These solutions often use RFID tags as the building blocks of technologies as the Internet of Things and cloud computing.

This report intends to give a survey of RFID-based information integration solutions and show its appli-cations and feasibility, thereby focussing on tracking and tracing in complex manufacturing. The report is organized as follows. Chapter 2 defines the scope of the literature review by elaborating on complex man-ufacturing, tracking and tracing and its requirements for information integration. Chapter 3 will focus on the role of RFID technology within tracking and tracing in complex manufacturing. Hereafter, chapter 4 will show the results of a survey on the different information integration solutions and show its feasibility. Finally, chapter 5 will elaborate and current and future implementations of RFID enabled information integration.

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2 Survey scope

Before examining information integration solutions, it is important to clearly define the scope of the survey. As stated, this report intends to give an overview of RFID-based information integration solutions and their feasibility within tracking and tracing in complex manufacturing. Both complex manufacturing and tracking and tracing are terms which are interpreted differently in literature. This chapter intends to clearly define the authors’ view of complex manufacturing and tracking and tracing, thereby creating a set of requirements for information integration solutions and objectives for the survey.

2.1 Complex manufacturing

According to the Oxford dictionary, manufacturing is ’the act of making something on a large scale using machinery’. Most modern high-technology enterprises show very complex manufacturing systems. A typical example of complex manufacturing in the automotive industry can be seen in figure 1. A manufacturing system becomes complex due to the following factors [7]:

• Multiple part types used on the same production line

• Large amounts of manufacturing steps (up to 500 steps is common in complex manufacturing) • Complex operations as rework, parallel processes and feed forwarding

• Machine breakdowns

• High-technology equipment which may require a high level of maintenance and multiple levels of sub assembly.

Complex manufacturing systems require a great set of rules and models, since maintaining and setting up such a system brings along high costs. These models are intended to support management decisions and require a great amount of data [7]. Since the processes within complex manufacturing often have multiple constraints, goals and high uncertainty, the quality of the model relies on fast and accurate data. RFID technology is one of the main enablers of this kind of data generation.

Four main advantages of RFID over traditional identification systems can be identified [9]. At first, the RFID tags do not require a line of sight to be read. Also the tags are less sensitive to dirt and grease. Thirdly, multiple tags can be read simultaneously. And finally, RFID tags can be read and written and can store more information than, for example, a bar code. These advantages are especially valid in manufacturing environments where the tact time is low, there are little worker idle times and rework is present and costly. These environments are visible in complex mass-production, for example in car and aircraft industries.

2.2 RFID applications within complex manufacturing

RFID applications started primarily in the access control and toll collection [9]. Nowadays a lot more applica-tions have been found in, for example, port operaapplica-tions, animal tracking and anti-theft applicaapplica-tions. Although

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Figure 1: A typical example of complex manufacturing at Fords Kansas City Assembly Plant [8]

the technology of RFID has been around for decades, its large-scale use started only ten years ago with the implementation in the supply chain of Wal-Mart[9]. Soon, other big companies followed. Still, its applications where mainly focussed on logistics and supply-chains, with less attention for the use of RFID in manufacturing. Up till now, few real life case stories exist and therefore the academic literature of potential applications is limited [10]. More information on the reason for the lack of current implementation can be found in chapter 5.

In general, the applications of RFID technology in manufacturing can be divided in three categories. Together they make up so-called ubiquitous manufacturing, which is the term for automatic data collection and real-time data processing in manufacturing [11]. Each category in itself can have different applications, as is shown in figure 2. This section will shortly handle information supply and planning control. Since Tracking and Tracing is chosen as the scope for the survey, this category will be more extensively elaborated on than the others.

2.2.1 Tracking and tracing

Tracking is identified as the activity with the result of real-time knowledge of the location of the part which is tracked [4]. Tracking allows real-time data usage to maximize efficiency and monitor the production lines.

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Figure 2: Different types of RFID applications in manufacturing

Traceability is seen as the ability to recreate the manufacturing steps, processes and locations of a part[4]. Tracing allows fast containment of parts which need additional handling or have received incorrect handling. Tracking and tracing is currently becoming more and more important as quality control is increasing. Especially in multi-level supply chains, tracking and tracing can generate a digital fingerprint of any specific product, thereby ensuring complete transparency [12]. Within the category of tracking and tracing, a few applications can be thought of:

• monitoring production: In manufacturing, monitoring of products can be achieved by tracking and tracing the product. By positioning read points at manufacturing steps, manufacturers can monitor errors, location, usability, maintenance requirements and efficiency without human interception [13]. This way, bottlenecks can be found easily, maintenance can be scheduled more effectively and optimizing efficiency becomes easier just as error-free manufacturing. All of this will lead to reducing down time and increasing throughput.

In contradiction to complex assembly, in low variation part fabrication the separate parts are often not tagged piece by piece, but per cart or pallet[13]. This is due to costs and time. However, in order to fully utilize the potential of RFID technology, tagging per unit is beneficial. Therefore, most applications are found in valuable parts manufacturing with high variety or complex assembly [13].

This technology is especially valuable for companies like car manufacturers, who deal with an extremely complex supply-chain, over viewing multiple customers and suppliers [14]. Big manufacturers as Ford and Toyota are known to use RFID for accurate and efficient routing and identification of vehicles and parts through an automated production line. This way, every unit of trade and move is immediately reported.

• Inventory management: RFID information can be used in warehouses or manufacturing inventories of raw goods and finished products. By labelling every product or pallet in a warehouse, management can track any move and handling. By coupling the tracking of goods with an inventory management system, an easy and up to date overview of the inventory can be made [15]. Hereby, it becomes easy to check

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and optimize the handling of the products and be up to date as to the levels in the warehouses [16]. Complete transparency of the inventory is another important tool for lean-manufacturing [10]. In this way, orders to the suppliers can be made automatically and just in time. Also, warehousing strategies as kanban, Just-in-Time and pull-based supply can be aided by RFID.

• Asset management: Tracking of movable assets like tools or vehicles has always been an enormous challenge[17]. It seems specifically difficult to find a cheap solution for accurate stored information. This often leads to employees wasting a lot of time searching for assets. Also, missing assets could have disastrous results, think of for example the possible outcomes of lost tools on an aircraft’s machine house. Real-Time-Locator Systems (RTLS) based on active RFID can pinpoint items to within a meter and can assist in asset management to identify the right asset, monitor its quality or status and keep history of assets [13][18]. Another large application of asset management can be found in returnables[19]. By storing information on where, for example, crates are going to, it is easy to see whether customers return the companies assets.

Current research also explores the ability to map RFID tags placed on products, robots or persons [20]. This way, mobile robots could accurately localize moving objects without being told where they are. This way, intelligent environments can be created, with intelligent behaviour of robots. Examples of this are expected to be found in the future of home automation, smart industrial plants and emergency applications [21].

2.2.2 Information supply

RFID tags have to ability to store information. In some cases, new information can be written on the tag during operation. This feature enables providing information locally and automatically. The following applications have been categorized:

• Manufacturing information: The first application within the domain of information supply is supplying manufacturing information. By installing readers at any production stage, RFID tags can indicate at any station which specific operation needs to be done[16]. This way, products with different colors, parts and finishing can be manufactured at the same line . In an automated area, the tags can even tell the machines at each stage which processes need to be carried out.

This application is also applicable for a job-shop type of manufacturing[13]. Logically, RFID tags can be used to simplify the information storage of all necessary handling of a product. This also enables further development of the modern manufacturing idea of lot splitting[22]. Within lot splitting, a large production requirement is split into smaller lots, which enables production of parts of a product to happen simultaneously. This way, the throughput can be increased significantly. Communication on the production floor is crucial for lot splitting, as production happens pull based and there is an increase in material flow. As RFID can automatically track tagged items, it is being widely evaluated for large scale introduction in lot splitting.

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In the food industry, the control of raw materials is crucial. Raw materials should be weighed, mixed and maybe even baked before the end product is received. By storing information on the materials at a local tag, a plant can improve its efficiency, accuracy and decline the number of errors [16].

• Handling history: Besides stating the processes to be performed, the part may keep its own manufac-turing history for purposes of warranty and continuous improvement[14]. In addition, this application makes it easier and more reliable to recall the right products when necessary and track where possible errors occurred.

• sensing: With recent developments in RFID technology it has become possible, besides storing informa-tion, to gather information with on-board sensors[6]. This way, it can be measured and checked whether critical environmental parameters are not exceeded. For example, it can be checked if a labelled package is not dropped, or exceeded a temperature range. This final statement can be crucial at the supply chain of perishable goods [23].

• Process of documents: An RFID system can be used to process legal documents [16]. By tagging products, information about the product can be stored locally. For example, if a product is outgoing on a port, readers can compare information of the product with the database. If everything is verified, the product is cleared to go. Besides time savings in processing and labour costs, this implementation will also reduce errors.

2.2.3 Planning control

The last category of possibilities for the use of RFID comprehends the idea to integrate the generated information with the enterprise resource planning (ERP) and manufacturing execution system (MES) [24]. The ERP combines data across all functional departments like planning, inventory and production. With the help of the MES it uses the data to coordinate, monitor and execute internal business processes. By integrating information of RFID with the MES (and thereby ERP), an up to date automatic status of all products can be used. On the other way around, decisions made by the ERP can be written to the RFID tags [24]. In this way, the planning can be update with real-time data and can therefore be made more accurate and can be adapted faster. The way RFID information is sent to the ERP will be analysed in chapter 4.

RFID technology forms a good tool for prognostic logistics [4]. This concept comprehends the idea of using continuously generated data for accurate predictions of logistics demands. One could think of examples in production planning, but also maintenance, inventory strategies and delivery schedules. The expectations are that prognostic logistics could reduce insecurity of situations and therefore find failures at an early stages. RFID technology is ideal for prognostic logistics because of its fast, automatic and error free data collection. A supply chain where rapid product identification is crucial is the supply chain of perishable goods [25]. Here, RFID tags can identify up to date perishing product status at all stages of the chain. By identifying temperature and time periods, perishable product quality, and thus its pricing, can be established. This information is crucial to avoid waste and facilitate dynamic planning [25].

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2.3 Goals of RFID Tracking and Tracing in manufacturing

The application which will be centre of attention in this survey is tracking and tracing. Tracking and tracing is one of the most promising applications, as it gives opportunities to automate and optimize production lines and supply chains. Also, tracking and tracing makes it easy to detect theft and counterfeiting fast enough to be able to respond[4]. As was shown by data provided by Eurostat, few companies currently work with RFID tracking and tracing while a lot of companies are known to look into the possibilities [19]. As the author believes the greatest gains are yet to be achieved in RFID enabled tracking and tracing, this category is further explored in this section.

A system which is tracking objects must be able to provide the location, state and identity of an object. In this case, the RFID system is ought to keep track of items automatically. RFID systems are most likely to be implemented in complex manufacturing facilities, as they often work in an agile environment, which may require a lot of data. In order to successfully implement an RFID tracking and tracing system, the system must contribute to the following manufacturing goals.

2.3.1 Agile production

In the current market demand, we see a large increase in production innovation and product customization [26]. Customers seem to demand products with the latest capabilities and technologies. Also, large steps in product personalization is made. In for example the car industry, a customer can personalize a lot of features of the car, thereby the product will meet the customer demands exactly.

As product life cycles become shorter and product innovation and customization is increasing, a challenge for the manufacturers is arising. In order to fulfil current demands, production facilities must house production lines capable of handling multiple product variations [26]. Above this, in lean manufacturing environments, production is pull-based, thereby creating a varying demand for the production resources. This means that line capacity must be flexible in production type as well as in volume. For the tracking and tracing system, this means that it must be capable of handling large information flows, to make sure the right order arrives at the right place at the right time and receives the right handling.

In order to fulfil all of the current requirements, a good production management is necessary. This manage-ment ensures resource allocation, scheduling, documanage-ment control, quality managemanage-ment, recalls and performance analysis[26]. The basis of this management is made up of accurate, detailed and up-to-date information. RFID technology can provide of the data for the production management as it works fast and reliable.

2.3.2 Cost reduction

Currently, profit margins on products are to be very low. In order to meet demands of shareholders, customers and trading partners, the prices of products are often reduced [26]. In order for companies to still make a profit, manufacturing is an important area to search for improvements. Companies keep striving for optimal production and efficiency of its resources. This continuous search can be optimized with RFID technology as it gives a real-time database of the production resources.

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2.3.3 Supply chain compatibility

In order to be able to track and trace a product, it must be possible to track and trace at any facility in the supply chain. Imagine that an aerospace major might use 5000 different parts for an aircraft, coming from different suppliers [26]. This logically generates a huge flow of data and managing. Often, smaller suppliers may not have invested in automatic tracking and tracing leading to outdated shipping information [27].

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3 RFID technology

In many current cases, information management is facilitated by bar code scanning [19]. As complexity of manufacturing systems grows and the market changes demand agile production, more manufacturing enterprises are looking into RFID systems. This chapter will present the basics of RFID technology, thereby showing how RFID technology can satisfy the goals for tracking and tracing in manufacturing as presented in Chapter 2. First, an historic overview will be presented to show the path of RFID technology up till now. Hereafter, RFID technology and its applications will be presented.

3.1 Historic overview

Since the start of manufacturing on a large scale, rapid identification techniques have been developed to help the handling of goods and materials [6]. For a long time, this happened with printed labels or engraved codes. In the 1970s, labelling took a huge step with the introduction of bar codes with a Universal Product Code [9]. These bar codes were initially intended for grocery stores, but soon found a way in other applications. Still, bar codes showed many limitations in the form that it requires a clear line of sight between reader and label, can only be read by one at the time, are easily effected by grease and dirt and has limited storage capacity [9]. Therefore, in the meanwhile other identifying technologies were researched.

In 1886, Hertz was the first to transmit and receive radio waves[28]. The first halve of the 20th century saw further development of the use of radio waves and in the 1920s, it was possible to identify objects with the use of radio waves[28]. This technology was rarely used until World War II, where radar-technology was commonly utilized to identify air crafts. The technology proved to be very effective for military purposes and the attention on radio waves techniques increased. During this boost, the developments of RFID for commercial goals started [28].

One of the first to explore the use of RFID is Harry Stockman in his ’Communication by Means of Reflected Power’, published in 1948 [28]. The 1950s and 1960s marked the development of RFID technology as computers, integrated circuits, lasers and digital data networks were established [29]. In the late 1960s and 1970s, commercial activities began in access control and electronic article surveillance [29]. 1973 Saw the first RFID tag as it is known now, patented by Mario Cardullo. The initial device was demonstrated in 1971 to, among others, the New York Port Authority for use as a tolling device[28]. In 1973, Los Alamos National Laboratory demonstrated a 1-bit tag that made it possible to simply detect a tag [6]. One of the first applications was use of RFID tags in employees badges to identify and, where necessary, limit access.

In the 1980s, implementation of RFID technology in the fields of transportation, personnel access and animal tracking were started [28]. In Europe, toll roads were equipped with RFID technology. PCs allowed collection and management of data. Until well in the 1990s, RFID technology remained obscure for the large audience. It wasn’t until the introduction of RFID tags in the supply chains of Wal-Mart, Tesco and the US department of defence before RFID tags were widely implemented [6]. From here on, the scale of implementation increased. Across the globe, implementations in rail cars, tolling collection, fuel dispensing, gambling games, ski passes and vehicle access were realized [6].

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3.2 RFID working principle

The historic background of the RFID shows its advantages over bar codes and a few applications. Still, it took 50 years since its birth before RFID technology became mainstream. This is primarily caused by the high costs of electronic identification[6]. Although RFID still isn’t as cheap as labelling technologies, it does offer added value and seems to have overcome the point where the costs dominate the rewards [6]. An RFID system generally consists of tags, readers and a back-end system to link all information. The tags and readers will be elaborated on in this section, while information on the back-end system will be supplied in a later chapter.

3.2.1 Tags

A tag (or transponder) consists of of three components [4]. At first, the antenna sends and receives signals. Secondly, the chip is an integrated circuit which may house, among others, a memory, control logic and a modulator. Finally, the casing protects the tag. The tags are available in a variety of shapes and sizes [30]. Special casings exist for usage in animals, credit cards or other harsh environments. The smallest tags commercially available are below a millimetre in cross-section and as thick as a slide of paper. A few examples can be seen in figure 3.

At the basics, RFID tags can be divided in passive and active tags. Active tags require an internal power source, which is often an integrated battery[16]. Active tags are often expensive, large in size and have a limited life-time but also a large read range. They are often used for higher-value goods that need to be scanned over longer distances. Passive RFID tags, in contrary, receive energy from the reader [6]. Although they are small and cheap, its read range is lower, a reader with more power is required and it cannot easily incorporate other technology as GPS or additional memory. Passive tags only consist of an antenna and an

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Figure 4: basic RFID-system architecture [34]

semi-conductor chip to modulate and regulate the transmission of data. The antenna captures energy from the reader and transfer the tag’s ID . Finally, there are also semi-passive tags where a battery runs the chips circuitry but the tag communicates passive [9].

3.2.2 Readers

A tag reader, or transceiver, consists of a radio frequency module, a control unit and an antenna [32]. In addition, many readers use interfaces that enables them to communicate with a data processing subsystem, for example a database. The antenna physically sends and captures waves to and from the tags. The control unit ensures the communication with the software, control of communication with the transponder and does the signal coding and anti-collision, which is explained later in this chapter[32]. The radio frequency module does the transmitting and receiving: this incorporates modulation and transferring of signals to data to be send and vice versa[33]. Practically, it forms the bridge between antenna and control unit.

The reading and writing works in a master-slave principle [33]. All the actions of the readers are initiated by the back-end software. The tags are turned on by the reader. As soon as the tag is communicating with the reader, the software takes over from the reader and is thus master. The very basic architecture is shown in figure 4. A more elaborate analysis of system architectures will follow later in the report.

Readers may differ in complexity, shape and therefore price [4]. Readers can be fixed to a point or can be hand-held. Fixed readers can support larger components, making them capable of reading at a larger range.

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Figure 5: Inductive coupling explained [36]

3.2.3 Communication

Passive and active tags communicate with the reader in different ways. Active tags simply send out its ID signal periodically [33]. Its small battery is activated when it is in the presence of a reader. The technology behind passive tags is a bit more complicated as it requires an external power source [33]. Transferring this power for passive tags can be done in two different approaches: with either magnetic induction (near-field) or electromagnetic (EM)wave capture (far-field) [32]. In some applications where close coupling (<1 cm) is required, capacitive transmission is even possible. Since this is not often used, this technology is not further reviewed.

In near-field operation (within the range of 1 meter), a reader creates an alternating current through a coil which results in an alternating magnetic field [35]. A tag has a smaller coil and will, when in presence of the reader’s magnetic field, generate an alternating voltage. Rectifying this voltage with a diode and accumulating its energy on a capacitor will make it possible to power the tag chip. The tag, in its turn, sends data back to the reader using load modulation [6]. This is achieved by creating a current in the tag’s coil which will cause an own small magnetic field, opposing the field of the reader. The reader coil will detect this as a small deviation in current flowing through it. If the tag’s electronics varies the load it applies over time, a signal can be encoded as variations in the field strength [32]. Figure 5 clarifies this technology visually.

Far-field communication (range larger then 1 meter) is based on EM waves, sent from a dipole antenna in the reader [6]. A smaller dipole antenna in the tag receives energy as an potential difference that appears across the arms of the dipole. Again, after rectification and accumulation, the tag’s electronics can be powered. Unlike the inductive designs, the tags are here beyond near-field and therefore information can’t be transmitted back with load modulation. Instead, back scattering is used. In back scattering, the antenna is tuned to a particular frequency at which it can absorb the most energy. If an impedance mismatch occurs, the antenna will reflect back a portion of the energy as tiny waves. Again, the reader can detect these waves. By changing the impedance of the antenna over time, the tag can reflect a pattern as a message.

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3.3 RFID suitability

Intelligent tracking was first described by Brewer in 1999 [37]. It comprehends the tracking and tracing of items without human intervention, thereby reducing the time needed between handling and improving efficiency. This can be done with the help of emerging technologies as GPS or RFID.

As described earlier, tracking and tracing activities in manufacturing can be divided in asset utilization management, inventory control and line monitoring. With RFID technology, real-time field data is pro-cessed automatically, thereby reducing error-prone, manual and especially costly activities [38]. In real-life manufacturing facilities, production information is often unavailable or difficult to retrieve, which results in inaccurate, old manufacturing data. As this data is used for the managing of production, this results in excessive Work-In-Process and inaccurate line management.

RFID is mostly used in complex mass-manufacturing due to its capability to work fast and store a lot of information. These industries often operate with lean manufacturing principles [10][39]. Its most important goal is manufacturing with a minimum of seven forms of waste. High data quality, obtained by RFID, can help reduce these forms of waste. For example, read errors can be prevented by scanning RFID instead of bar codes, walking distances for scanning disappear, overproduction can be minimized by inventory management with automatic kanban and tracking of products can optimize transport and minimize waiting times.

Still, the suitability of RFID technology for reaching the goals of tracking and tracing in complex manufac-turing as described in chapter 2, depend on characteristics of RFID. This section will elaborate on a few of these characteristics.

3.3.1 Operating frequencies

Frequencies are typically allocated by legislation and regulation and differ across the world [4]. RFID systems are categorized in radio systems and may not interfere with other radio systems. Therefore, RFID systems operate in ranges specifically reserved for industrial applications.

Generally, Low Frequency bands are known as 30-300 kHz, High Frequencies as 3-30 MHz, Ultra-High frequencies as 300 MHz 3 GHz MHZ and Microwave as higher than 3 GHz [33]. Exact frequency ranges for different regions can be found in table 1. Due to their on-board battery, active tags also operate at high frequencies, commonly 455 MHz, 2.4 GHz or 5.8 GHz [35].

3.3.2 Read ranges

Read ranges depend, among others, on the power of the reader and frequency used to communicate. A tag generally requires between 10 uW and 1 mW for operation [16]. In general, higher-frequency tags can be read from greater distances but require more energy [16]. Lower frequencies work more efficient within a smaller range and show more penetration.

Read ranges can differ from 1 centimeter up to 100 meter [35]. Close coupling systems can operate with a range up to 1 centimeter, these systems often function at frequencies up to 30 MHz [4]. This type is often used in security systems and is not found often in manufacturing or tracking and tracing because of its low

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Table 1: RFID frequency ranges [4]. ERP here stands for Effective Radiated Power and LBT for Listen Before Talk

range. Remote coupling systems (Near-field) can work with up to 1 meter range and function in the Low or High Frequency range. These systems communicate with inductive coupling and are most often used in complex manufacturing and tracking and tracing at fixed positions. Far-field systems operate with ranges above 1 meter and use Ultra-High frequencies or Microwaves. Passive tags may reach up to 3 meters, active up to 100 meter [35].

Unfortunately, metal alters the resonant frequency of the tag, which makes it a challenge to tag metal objects [33]. This effect an be minimized by the use of low frequencies,which show better penetration. Of course, this results in lower read ranges. Also, Active tags can be used on metals, as they show less influence by metal and have larger read ranges [40].

Within the domain of tracking and tracing in complex manufacturing, it is important to define the intention and physical design of the facilities before designing an RFID system. Remote coupling systems may be generally used, but as described, the tags must pass the reader within one meter in order to be read. Therefore, for applications as asset management, other tags with higher ranges may be required. Also, the composition of the environment and products must be accounted for since metal and liquids may alter the signals.

3.3.3 Memory

RFID tags can house a chip in order to store information. The memory in an RFID tag can be read-only, write-once/read many or read/write [4]. Read-only chips are programmed during production and cannot be altered. Write-once/read many memory can be written by the user once, however it cannot be changed hereafter. Read/write memory can embed new information and are more expensive than read-only chips. These tags incorporate EEPROM, while other tags incorporate ROM (read-only, WORM(Write Once, Read Many) or RAM (read-write) [29].

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Within tracking in complex manufacturing, manufacturers may only require a read-only function. In this way, a tag can carry its unique ID. When a reader at a fixed position reads this ID, the system knows that this particular piece was at that particular location at this particular time. Read/write memory may add additional tracing facilities to the system. This way, the system may locally record information on the production stages or environmental issues. This may be important to for warranty purposes or , for example, products which may only be kept at a certain temperature range.

3.3.4 Coding

As stated, EPC global was organized to establish the electronic product code (EPC) network as a global standard, as a successor to the bar code. Currently, the EPC is most used as RFID code standard [16]. It consists of three sets of data. These sets represent the EPC manager, the object class and serial number. The manager identifies the manufacturer of the product, the object class refers to the exact type of product and the serial number is the unique code that specifies the specific product . By standardizing the code on the tag, it is ensured that the tags may be read and interpreted the same away among different partners within the supply chain.

The transmission of the code can generally be divided in two categories: level codes and transition codes[32]. Where level codes represent a bit in voltage level, transition codes represent a bit by a change in power level. Level codes tend to be less robust and therefore transition codes like Manchester PPM, PWM or NRZ are used most often. The stream of bits is digitally modulated before it is transmitted. Three classes of modulation are used: Amplitude Shift Keying, Frequency Shift Keying and Phase Shift Keying [32].

3.3.5 Collision

One of the main advantages of RFID technology over bar codes is that multiple RFID tags can be read simultaneously [9]. Hereby a higher read speed and data transfer is ensured, which is required for agile production monitoring. However, when multiple tags correspond with the reader simultaneously, their signals can interfere with each other. This way, products or assets could be misread and maybe get lost or traced improperly. This interference is called collision and typically leads to distorted signalling [32]. In order to ensure error-free communications with multiple tags communicating at the same time, an anti-collision method has to be applied. A lot of tag anti-collision algorithms have been developed [32]. However, since the goal of this paper is merely to overview information integration solutions, only the two most commonly used algorithms will be briefly examined: the deterministic and probabilistic algorithm.

In probabilistic algorithms, the tags respond at random intervals after they are initiated. One of the most used algorithms is ALOHA [40]. Here each transponder receives a wake-up call by the reader. After this, every tag will respond its identification number after a random time slot. Several rounds may be necessary, as there is still a change that multiple time slots overlap. In deterministic schemes, the reader sorts the tags based on their identification number [6]. The most used anti-collision algorithms use the tree-based (or binary search) algorithm. Here, the reader asks for the firsts digits of the identification number of the tags. It continues this way, until only one number remains, which complies with the number of the reader. The

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tree-based principle ensures that as soon as a digit does not comply, its branches are no longer evaluated, as shown in figure 6. Another deterministic algorithms often used is time division multiple access [4]. Here, the capacity of the communications channel is divided in time over the tags, thereby allocating a unique time slot for every tag. In practice, deterministic algorithms work faster and are most commonly used [4].

Besides tag collision, also reader collision may occur. This may happen when readers are within each others reading range, as a tag may respond to multiple readers at the same time [32]. The solution is found by allocating frequencies over time to a set of readers. These so-called agile readers, can read chips at different times with different frequencies. Besides the fact that this solves the problem of reader-collision, it also ensures that the reader is usable in different environments and countries, as different frequencies are assigned for RFID usage in different countries [16].

3.3.6 Costs

The Auto-ID center was organized at Massachusetts Institute of Technology (MIT) to bring together RFID manufacturers, researchers and users to develop standards, research and share information about applications [16]. In late 2003, EPCglobal was organised by the auto-ID center, in cooperation with the labs of five leading research universities and with sponsoring by more than 100 firms and organizations. It had two main goals. The first is to establish worldwide standardization of EPC (electronic product code). This has succeeded and EPCglobal network now develops infrastructures for companies. The second goal was to reduce costs of a passive RFID tag to below five cents [42], which is believed to be the break-even point for large-scale implementation.

Current prices generally lay between seven and fifteen cents per tag for passive tags [19], although the first manufacturer has achieved to break the barrier of five cents [42]. Active tags are currently being sold for a price between 10 and 40 dollar [43]. Readers are rapidly declining in price and can now be found for less than 1000 Euro [19]. Although the five cent limit is not yet reached, it is believed that RFID technology

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may already add value for certain purposes in certain markets. Especially in complex manufacturing or asset management, the value of tagged products may be very high, thereby lowering the break-even point for overall cost reduction. Also, prices of passive tags are expected to keep dropping in the coming years, thereby it is expected that the five-cent barrier will soon be reached [4].

Although it seems that RFID technology brings a lot of benefits, it should be reminded that putting a true value on the implementation of RFID in tracking and tracing is difficult [44]. The benefits of RFID will come in improved forecasts, reduced inventory and labour costs savings, it proves to be difficult to put a definite number on the benefits of RFID implementation. Due to unrecognised value of RFID implementation and the economic climate of the last years, the implementation of RFID systems in manufacturing is still little.

3.3.7 Privacy and security

As stated, RFID technology houses many benefits, although its main challenges lie primarily in costs and secondarily in privacy and security concerns. As the costs decrease throughout the years, the usage of RFID technology increases. Its privacy and security concerns may therefore now be bigger than ever. Although the main intention of RFID is to track goods or persons, it may bring along some undesirable outcomes for many customers. The main problem and cause of concern is that the technology is wireless and therefore we don’t directly know when communication is occurring [4]. Although most RFID tags cannot alter something or make decisions, as it is a passive device, the scale of the systems and data flows will bring a lot of new problems and challenges to security and privacy.

In general, two main privacy concerns for users exist: clandestine tracking and inventorying. As RFID tags respond to a reader without alerting, scanning (and therefore tracking) of tags can be done without permission [29]. Effectively a customer with an RFID tag is dragging around a broadcast of a fixed number. This number can be read by any reader, theoretically making it possible to track the person easily. This is not merely true for RFID; cell phones, blue tooth devices and other wireless devices are subject to the same issue.

With inventorying is meant that the information on the tag is coupled to the products a customers is carrying [45]. This way personal information can easily be harvested. If a personal tag houses personal information, a shop might establish a link between the customers identity and product. Marketers can then easily identify and profile consumers. To address these concerns, big RFID manufacturers and establishers of RFID tags like EPCglobal and RCA have designed a kill switch on their tags [6]. This lets vendors permanently disable a tag on the point of sale.

Although all these concerns may seem consumer related, the supply-chain visibility may also betray intel-ligence [45]. In military related chains, enemy forces could hack software and thereby monitor and harvest information about troop movements. The same counts for manufacturing supply chains. Competitors could theoretically acquire information on stock turnover rates and therefore reduce competitive advantage. Other threats consist of flooding an area with RF energy, replicating tags or initiating a technical attack [29].

On the other hand RFID authentication is a big opportunity for the use of RFID in the fight against stolen goods, which is especially viable for expensive (often complex manufactured) goods [45]. Currently, RFID

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tags are already used in cars ignition to authenticate the key. Also, RFID tags could be placed on partials to verify whether it has been opened during transport. The food and drug administration has already placed tags on pallets and cases of medicines to combat counterfeits.

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4 Overview of information integration solutions

Now that it has shown that RFID can enable data collection of the location and state of products, it is necessary to look into information integration. To enable tracking and tracing, the system must integrate information of multiple readers to clarify the path of a certain product. Within tracking and tracing for manufacturing, several information integration solutions have been proposed and implemented. This chapter intends to give an overview of architectures and infrastructures behind RFID systems and show their feasibility. In literature, the terms infrastructure, architecture and framework are often used inconsistently, which makes it difficult to establish a comprehensive overview of information integration solutions. In order to prevent confusion, these terms are first explicitly defined by the author before being used.

• Infrastructure: Infrastructure can be defined as the hardware of an IT system. It comprises the tags and readers, but also the physical properties of the network as databases and controller. In this way, the infrastructure carries the architecture, just as the foundation of a building. Infrastructure therefore defines the robustness and capacity of the system.

• Architecture: The system architecture defines how all the assets work together. This is usually repre-sented in a schedule. The architectural design is were the system becomes tangible, while an infrastruc-tural design is more conceptual and abstract, as it does not define relationships between assets. • Framework: The framework is the starting point to build a system. The framework yet is very abstract.It

can be seen as a collection of resources and facilities, without any structure. Since frameworks are only used for conceptual models, these will not be regarded in this survey.

4.1 Infrastructure

Although the functionality of the separate components of an RFID system have been described extensively, some additional requirements of an RFID infrastructure must be obeyed for the components to perform well in tracking and tracing system. A previous chapter introduced tracking and tracing as an RFID application. Its reliability and functionality relies on the following infrastructural characteristics [5]:

• Amount of tags read at the same time: When reading items on a batch size (for example on a pallet) or items close to each other, it is important that multiple tags can be read at the same time. Although this generates some initial problems, these can be solved by the previously described anti-collision algorithms. • Read speed: In a manufacturing environment, goods may pass a reader at a fast pace. It is important that a reader can read a tag within the time that the tag passes. Also, anti-collision algorithms must be fast enough the read a passing batch in time.

• Processing time: RFID tags obviously generate a large amount of data. When it is necessary to be able to make fast decisions, this data must be handled quick as well. Filtering of data may help enable fast handling.

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The infrastructure must fulfil three communication paths: data processing, device management and device control [46]. That data path refers to the information of the tag which is collected and forwarded to the network and applications. The management paths takes care of the monitoring and management of the devices. Finally, the control path operates the readers. Here, it is important to define whether the data collection is closed, open or cross-enterprise. If the data remains indoors, this requires a different infrastructure then when suppliers and customer have open access or can request information at the company.

4.1.1 Tag placement

In order to track and trace on a production floor, it is crucial to identify the resources to which tags or readers need to be attached. Pallets of products or individual products are tagged, depending on the products’ customization and value [47]. Mostly, uniform, low-value products are tagged per pallet or crate. High-value products who require custom processes are tagged individually to track its history and secure its value.

A piece of equipment or part equipped with a tag is called a smart object, when multiple smart objects can communicate autonomously, these are named to be intelligent [48]. Tags can be deployed in different schemes, the determination of the best scheme is dependent on the application. The information recorded for critical components is often about who processes the material with what machine, together with the beginning and end time. This way, it monitors responsibilities and throughput. Minor materials are often only recorded for information about consumption. This information is used for replenishment. Optionally, data about breakdowns, and failures can be stored, thereby tracking Work-In-Process (WIP) items and performance of machines or operators[48].

Employees and critical tools can be tagged to track its real-time information and location[11]. Readers are often placed in the shop store room, production equipment as machines and robots, and transportation methods as Automated Guided Vehicles (AGVs). This way, the system can retrieve information of the location of a tag after every step of production or transport . Mostly, each shop floor houses a server which manages a group readers and collects their data.

RFID readers in manufacturing applications are mostly placed on machines and buffers [48]. The reason for this is that machines are the value adding steps in manufacturing which need to be monitored whereas the buffers are points were material and movement of materials can be traced and work-in-process can be measured real-time. Hand-held readers may be used for searching and asset management purposes.

In addition to the earlier described tags and readers, an RFID infrastructure mostly houses Reader Network controllers (RNCs), which is also called middleware, and applications which run on enterprise servers [46]. If necessary, other sensors or readers can also be incorporated, like bar code readers, I/O devices or printers.

Finally, a communication network needs to be established. Data communication from reader to middleware and back-end applications can occur via several channels. Applications have been found using USB or Ethernet, but most modern communication occurs via wi-fi.

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4.2 Basic Architecture

Information technology architecture is as old as information technology itself. At the start, in the 1960s, architecture often was based on a pyramidal shape, equivalent to the hierarchical structure of the company [49]. Staff members were at the bottom, entering data into the system. After filtering and aggregation, the data was compiled into tactical and, later, strategic reports. As the data collection evolved throughout the years, so did the data management systems. Currently, different architectures exist although the basics always consists of several layers.

4.2.1 Layers

The basics of most track and trace architectures are the same. It generally consists of three layers and a data center [48], [47]. The first layer is the physical manufacturing shop floor. The other layers make up the back-end system. The second is the information fusion layer (often filled in with a Manufacturing Execution System, MES), the third layer comprises the Enterprise Information System (EIS) and is called the enterprise application layer, as shown in figure 7. Finally, the data center provides information exchange and storage of data. The layers a thoroughly described as follows:

• Manufacturing shop floor: all the readers and tags, which are configured to the resources in order to capture enough relevant data

• Information fusion layer: The information fusion layer builds up the relations between the enterprise applications and the information capturing services. Separate systems have been proposed which coor-dinate a number of readers that are related in, for example, a production line. The servers connecting the readers and housing the software are called edges serves [49]. These edges servers run programs like MES (Manufacturing Execution System) but also the enterprise application software like ERP (Enterprise resource planning) system, which is used for the Enterprise application layer.

The MES its main goal is fulfilled by the middleware, which buffers, filters and aggregates raw data to reduce the load for the applications [49]. By providing data filtering, event handling and fusion of data were possible, the layer ensures visibility and traceability. It also has multiple functionalities which are designed as web services and houses planning and scheduling services and the executing of real-time production decisions.

For track and trace specific solutions, two additional modules are incorporated in the information fusion layer [50]. These are a track and trace module, which can provide the location of a part by obtaining real-time data of in or out flows at stations (read points). In addition, the monitoring and alerting module measures idle times and detects abnormal work flow procedures. In case of any mistake or error, it generates an alert. It ensures that the physical product can be tracked and traced with the use of RFID technology .Here, a connection to the internet can be implemented to allow partners to retrieve the information[48].

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Figure 7: Basic architecture scheme

The middleware in modern systems often follows a Service Oriented Architecture (SOA) [51].. This architecture ensures that complex systems are transferred into simpler and well-defined components. This has as an advantage that data can be shared and adapted in applications more easily, as it is easier to understand. Thereby the compatibility across the supply chain can be guaranteed.

• Enterprise application layer: The enterprise application layer is often filled in with an Enterprise Resource Planning (ERP) [52]. The ERP is an application that integrates information of various de-partments. It is a system that handles everything from sales to customer service. Also, it handles data storage and can retrieve information.

Its predecessors were similar systems with fewer options [52]. Material Resources Planning (MRP) only manages materials, while Master Production Scheduling (MPS) looks at production. ERP works enterprise-wide and integrates suppliers and customers with the manufacturing. Logically, the manufac-turing and inventory data can be retrieved with the use of RFID technology, to keep the ERP system up-to-date with real-time data which enables flexibility and dynamic planning.

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Figure 8: Hierarchical communication [53]

4.2.2 Communication between layers

By combining the use of RFID with the principles of the internet, internal and external communication can be established [53]. In applications at large areas, it is imaginable that multiple networks are required to cover the entire facility. These networks can be linked via the internet. Large facilities with a lot of relevant tags can be managed by a pyramid structure [53]. Here several RFID gateways can hold message from reader networks. When the messages are filtered, the messages can be passed on the Local, and later Global, Registration Centres (LRC and GRC)via LAN and internet, as can be seen in figure 8.

This generates a very hierarchical structure, where several readers communicate their information to gate-ways, which in turn communicate upwards with a central database. Also, a more heterarchical structure can be thought of, where all the readers communicate with one system via the internet.

Communication over the internet can also be implemented for external use, meaning with partners, suppliers or customers. If external users are allowed to digitally enter the enterprises system, they can access real-time data about production, Work-In-Process and product status. Although this informa-tion may be sensitive for the enterprise, it ensures visibility and traceability throughout the whole supply chain.

4.2.3 Bridge/Gateway architectures

Smaller heterarchical systems often exist for simple applications in a facility which requires only one network. It typically consist of an RFID reader network and a system network, which are connected via a bridge (figure 9) [53]. a switch links readers within the facility to read objects while the systems network houses the database and servers. Since the information is accumulated in the switch, before it is send to the system network, this is called a Bridge-based network.

The other architecture used for small systems is gateway based (figure 10) [53]. In this architecture, a gateway component collects the messages from multiple readers and manages the RFID information. This gateway component on the other side also communicates with the database and servers and is a central point. The gateway can also send its information via internet, thereby making it able for clients to log in and retrieve

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Figure 9: Bridge based architecture [53]

Figure 10: Gateway based architecture [53]

information. Its is very much alike the bridge architecture, however, since it filters information before sending, it reduces the loading of the system network making it viable for larger systems.

4.2.4 EPC Network

As stated earlier, EPC global is an organization which tries to define and implement global standards for the use of RFID technology. This started with the introduction of the Electronic Product Code (EPC) to code and recognize a particular object. The organization now also tries to define a standard RFID network, called the EPCNetwork [49]. It allows easy access and information exchange about products for producers, retailers

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and customers. With the introduction of the EPC and the EPC Network, EPCglobal tries to enable an easy way for companies within a supply chain to share the information they wish to share. In this way, companies increase their visibility within but also outside their walls. The network is intended to be able to work with any enterprise application, scale and standard and is free to use for any company [54].

A local EPC network of one company works mainly in the data fusion layer and partly in the enterprise application layer [55]. The data fusion layer in an EPC Network is made up of the savant, the Object Name Service (ONS), and the EPC Information Service (EPCIS). The EPCIS communicates with the enterprise application layer and can therefore also be considered outside the data fusion layer. The usage of these parts depends on the application. The parts have the following tasks:

• Savant: The savant is part of the middleware system and passes request from the enterprise applications to the readers [55]. It also receives data from the readers, which it filters and aggregates before sending it as information to the application. Filtering is its most important function, as it makes it possible to handle large amounts of data. Data will be filtered when it’s either redundant or useless for the application. Savants can also be integrated in readers and may directly communicate with external services as EPCIS and ONS.

• Object name service (ONS): The ONS is connected to the savant and its main goal is to translate the EPC code retrieved from a tag, to the valuable piece of information requested by an application or partner [55]. It uses the EPC to find the appropriate piece of information in its database. The ONS is based on existing internet technology to enable internet users to access information on the readers [54]. It is the technology that enables the network infrastructure to quickly share live data [5]. It does this by translating an EPC into one or more internet addresses (URL) where more information can be found. • EPC Information Service (EPCIS): The EPCIS ensures communication between any request of

infor-mation and the database, it thereby allows partners to exchange inforinfor-mation regarding the position of products in the chain [55]. The communication with the requester is always in PML (Physical Mark-up Language), while the communication with the database can be in any format, since databases run on different platforms with different programs.The EPCIS can communicate with any application or user, hereby making it the place which enables partners to communicate with the system of the enterprise [54]. For example, the URL generated in the ONS often is associated with the EPCIS. The EPCIS also supplements the applications and enables functions like track-and-trace and product authentication [46]. Within real-life manufacturing companies, the EPCIS is most commonly used of all EPC components [19]. Especially the last years, EPCIS is introduced in companies where communication throughout the supply chain is difficult. As stated earlier, most RFID systems are application-specific solutions. With the variation in systems comes along a variation in operating languages and protocols. EPCIS uses standards to form a bridge between companies with different operating languages and protocols, thereby making it possible to easily communicate over all companies in a chain.

In some companies, it may not be necessary to use all parts [55]. Therefore, this architecture is more a guideline than a strict functional design; it is intended to provide the users with flexibility in order to meet

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Figure 11: EPCNetwork architecture [55]

any need.If necessary, the savant, ONS and EPCIS can be used individually. Local EPC Networks can be connected through the internet to allow a global flow of data.

The components described earlier are connected as shown in figure 11. Such a schedule can represent an entire enterprise, but also a local part of the enterprise like a production line [55]. It can be seen that the reader identifies one or multiple tags as soon as these appear in the reader’s field. The reader reads the EPC of the tags and transfers these to the savant. If the savant determines that the application needs the information, the tag data is send to the application. If necessary, the data is put in the database via the EPCIS to store the data as required.

If the EPC is yet unknown in the system, the application asks the ONS to find the location of the information related to the EPC within the database [55]. If the ONS cannot find the information in the local database, the ONS will ask ONS systems higher up the hierarchy and can even make an enquiry to the global ONS via the internet. The enterprise can incorporate any application to communicate with the EPC network. Adoption of the database will be ensured by the EPCIS as this can communicate with databases which work with different languages.

RFID-based information integration in manufacturing-Op RFID gebaseerde informatie integratie in fabricage

Specialization: Transport Engineering and Logistics

Report number: 2014.TEL.7854

Title:

RFID-based information

integration in manufacturing

Author:

S. van den Brand

T

U

Delft

Summary

Contents

1

Introduction

2

Survey scope

2.1

Complex manufacturing

2.2

RFID applications within complex manufacturing

2.3

Goals of RFID Tracking and Tracing in manufacturing

3

RFID technology

3.1

Historic overview

3.2

RFID working principle

3.3

RFID suitability

4

Overview of information integration solutions

4.1

Infrastructure

4.2

Basic Architecture