计算机毕业设计钻具出入库自动检测系统毕业设计论文系列九英文原文.doc

1、英文原文：CHAPTER 1INTRODUCTION1.1WHAT IS RFID?RFID is an acronym for radio frequency identification, which is a wireless communication technology that is used to uniquely identify tagged objects or people. It has many applications. Some present-day examples include:Supply chain crate and pallet tracking

2、 applications, such as those being used by Wal-Mart and the Department of Defense (DoD) and their suppliersAccess control systems, such as keyless entry and employee identification devicesPoint-of-sale applications such as ExxonMobils SpeedpassAutomatic toll collection systems, such as those increas

3、ingly found at the entrances to bridges, tunnels, and turnpikesAnimal tracking devices, which have long been used in livestock manage-ment systems and are increasingly being used on petsVehicle tracking and immobilizersWrist and ankle bands for infant ID and securityThe applications dont end there.

4、In the coming years, new RFID applications will benefi t a wide range of industries and government agencies in ways that no other technology has ever been able.1.2 WHAT EXPLAINS THE CURRENT INTEREST IN RFID TECHNOLOGY?RFID is rapidly becoming a cost-effective technology. This is in large part due to

5、 the efforts of Wal-Mart and DoD to incorporate RFID technology into their supply chains.In 2003, with the aim of enabling pallet-level tracking of inventory, Wal-Mart issued an RFID mandate requiring its top 100 suppliers to begin tagging pallets and cases by January 1, 2005, with Electronic Produc

6、t Code (EPC) labels. (EPC is the first worldwide RFID technology standard.) DoD quickly followed suit and issued the same mandate to its top 100 suppliers. Since then, Wal-Mart has expanded its mandate by requiring all of its key suppliers to begin tagging cases and pallets. This drive to incorporat

7、e RFID technology into their supply chains is motivated by the increased shipping, receiving, and stocking efficiency and the decreased costs of labor, storage, and product loss that pallet-level visibility of inventory can offer.Wal-Mart and DoD are, respectively, the worlds largest retailer and th

8、e worlds largest supply chain operator. Due to the combined size of their opera-tions, the RFID mandates are spurring growth in the RFID industry and bringing this emerging technology into the mainstream. The mandates are seen to have the following effects:To organize the RFID industry under a commo

9、n technology standard, the lack of which has been a serious barrier to the industrys growthTo establish a hard schedule for the rollout of RFID technologys largest application to dateTo create an economy of scale for RFID tags, the high price of which has been another serious barrier to the industry

10、s growthSupply chain and asset management applications are expected to dominate RFID industry growth over the next several years. While presently these applications only account for a small portion of all tag sales, by late 2007, supply chain and asset management applications will account for 70% of

11、 all tag sales.As shown in Figure 1-1, the growth in total RFID transponder tags will have grown from 323 million units to 1,621 million units in just five years.Wal-Mart and DoD alone cannot account for all the current interest in RFID technology, however. Given the following forecasts of industry

12、growth, it becomes clear why RFID has begun to attract the notice of a wide range of industries and government agencies:In the past 50 years, approximately 1.5 billion RFID tags have been sold worldwide. Sales for 2007 alone are expected to exceed 1 billion and as many as 1 trillion could be deliver

13、ed by 2015.Wal-Marts top 100 suppliers alone could account for 1 billion tags sold annually.Revenues for the RFID industry were expected to hit $7.5 billion by 2006.Early adopters of RFID technology were able to lower supply chain costs by 35% and simultaneously increase revenue by 27% according to

14、a study by AMR Research.For the pharmaceutical industry alone, RFID-based solutions are pre-dicted to save more than $8 billion by 2006.In the retailing sector, item-level tagging could begin in as early as five years.In short, the use of RFID technology is expected to grow signifi cantly in the nex

15、t five years, and it is predicted that someday RFID tags will be as pervasive as bar codes.1.3 GOALS OF THIS BOOKThis book provides a broad overview and guide to RFID technology and its application. It is an effort to do the initial “homework” for the reader interested in better understanding RFID t

16、ools. It is written to provide an introduction for business leaders, supply chain improvement advocates, and technologists to help them adopt RFID tools for their unique applications, and provide the basic information for better understanding RFID.The book describes and addresses the following:How R

17、FID works, how its used, and who is using it.The history of RFID technology, the current state of the art, and where RFID is expected to be taken in the future.The role of middleware software to route data between the RFID network and the information technology (IT) systems within an organization.Th

18、e use of RFID technology in both commercial and government applications.The role and value of RFID industry standards and the current regulatory compliance environment.The issues faced by the public and industry regarding the wide-scale deployment of RFID technology.CHAPTER 2AN OVERVIEW OF RFID TECH

19、NOLOGY2.1 THE THREE CORE COMPONENTS OF AN RFID SYSTEMAn RFID system uses wireless radio communication technology to uniquely identify tagged objects or people. There are three basic components to an RFID system, as shown in Figure 2-1:1.A tag (sometimes called a transponder), which is composed of a

20、semi-conductor chip, an antenna, and sometimes a battery2.An interrogator (sometimes called a reader or a read/write device), which is composed of an antenna, an RF electronics module, and a control electronics module3.A controller (sometimes called a host), which most often takes the form of a PC o

21、r a workstation running database and control (often called middleware) softwareThe tag and the interrogator communicate information between one another via radio waves. When a tagged object enters the read zone of an interrogator, the interrogator signals the tag to transmit its stored data. Tags ca

22、n hold many kinds of information about the objects they are attached to, including serial numbers, time stamps, configuration instructions, and much more. Once the interrogator has received the tags data, that information is relayed back to the controller via a standard network interface, such as an

23、 ethernet LAN or even the internet. The controller can then use that informa-tion for a variety of purposes. For instance, the controller could use the data to simply inventory the object in a database, or it could use the information to redirect the object on a conveyor belt system.An RFID system c

24、ould consist of many interrogators spread across a ware-house facility or along an assembly line. However, all of these interrogators could be networked to a single controller. Similarly, a single interrogator can communicate with more than one tag simultaneously. In fact, at the present state of te

25、chnology, simultaneous communication at a rate of 1,000 tags persecond is possible, with an accuracy that exceeds 98%.Finally, RFID tags can be attached to virtually anything, from a pallet, to a newborn baby, to a box on a store shelf.2.2 RFID TAGSThe basic function of an RFID tag is to store data

26、and transmit data to the interrogator. At its most basic, a tag consists of an electronics chip and an antenna (see Figure 2-2) encapsulated in a package to form a usable tag, such as a packing label that might be attached to a box. Generally, the chip contains memory where data may be stored and re

27、ad from and sometimes written, too, in addition to other important circuitry. Some tags also contain batteries, and this is what differentiates active tags from passive tags.2.2.1 Active vs. Passive TagsRFID tags are said to be active if they contain an on-board power source, such as a battery. When

28、 the tag needs to transmit data to the interrogator, it uses this source to derive the power for the transmission, much the way a cell phone uses a battery. Because of this, active tags can communicate with less powerful interrogators and can transmit information over much longer ranges, up to hundr

29、eds of feet. Furthermore, these types of tags typically have larger memories, up to 128 Kbytes.However, they are much larger and more complex than their passive counterparts too, making them more expensive to produce. The batteries in active tags can last from two to seven years.Passive RFID tags ha

30、ve no on-board power source. Instead, they derive power to transmit data from the signal sent by the interrogator, though much less than if a battery-were on-board. As a result of this, passive tags are typically smaller and less expensive to produce than active tags. However, the effective range of

31、 passive tags is much shorter than that of active tags, some-times under two feet. (Compare a battery-powered megaphone to an old-fashioned plastic cone.) Furthermore, they require more powerful interrogators and have less memory capacity, on the order of a few kilobytes.Some passive tags do have ba

32、tteries on-board but do not use these batteries to assist in radio signal transmission. These types of passive tags are called battery-assisted tags and they use the battery only to power on-board electron-ics. For example, a food producer may apply RFID tags equipped with temperature sensors to pal

33、lets in order to monitor the temperature of their product during shipment and storage. Were the temperature of the product to rise above a certain level, that occurrence could be marked on the tag automatically by the sensor. Later, at the time of delivery or sale, the tag could be checked to verify

34、 proper shipment or storage. Passive tags equipped with this type of peripheral sensor would need an on-board battery to operate during shipment or storage.2.2.2 Read-Only vs. Read/Write or “Smart” TagsAnother differentiating factor between tags is memory type. There are roughly two kinds: read-only

35、 (RO) and read/write (RW).RO memory is just that; memory that can be read only. RO tags are similar to bar codes in that they are programmed once, by a product manufacturer for instance, and from thereon cannot be altered, much the way a CD-ROM cannot be altered after its burned at the factory. Thes

36、e types of tags are usually programmed with a very limited amount of data that is intended to be static, such as serial and part numbers, and are easily integrated into existing bar code systems.RW tags are often called “smart” tags. Smart tags present the user with much more fl exibility than RO ta

37、gs. They can store large amounts of data and have an addressable memory that is easily changed. Data on an RW tag can be erased and re-written thousands of times, much the same way a floppy disk can be erased and re-written at will. Because of this, the tag can act as a “traveling” database of sorts

38、, in which important dynamic information is carried by the tag, rather than centralized at the controller. The application possibili-ties for smart tags are seemingly endless. This, in addition to recent advances in smart tag technology that have driven production costs down to under $1 per tag,acco

39、unts for much of the present interest in RFID systems.There are a few variations on these two types of memory that need mentioning. First, there is another memory type called write-once-read-many (WORM). It is similar to RO in that it is intended to be programmed with static information. Drawing on

40、the analogy above, if RO is similar to a CD-ROM, then WORM would be akin to CDRW, in which an end-user, a PC owner for instance, gets one chance only to write in its own information, i.e., burn a blank CD. This type of memory could be used on an assembly line to stamp the manufacturing date or locat

41、ion onto a tag after the production process is complete.In addition, some tags could contain both RO and RW memory at the same time. For example, an RFID tag attached to a pallet could be marked with a serial number for the pallet in the RO section of the memory, which would remain static for the li

42、fe of the pallet. The RW section could then be used to indicate the contents of the pallet at any given time, and when a pallet is cleared and reloaded with new merchandise, the RW section of the memory could be re-written to reflect the change.2.2.3 Tag Form FactorsRFID tags can come in many forms

43、and may not resemble an actual tag at all. Because the chip/antenna assembly in an RFID tag has been made so small, they can now be incorporated into almost any form factor:Some of the earliest RFID systems were used in livestock management, and the tags were like little plastic “bullets” attached t

44、o the ears of livestock.The RFID tags used in automatic toll collection systems are not really tags but plastic cards or key chain type wands.In prison management applications, RFID tags are being incorporated into wristbands worn by inmates and guards. Similarly, some FedEx drivers carry RFID wrist

45、bands in lieu of a key chain to access their vans through keyless entrance and ignition systems.The pharmaceutical industry is incorporating RFID tags into the walls of injection-molded plastic containers, thus blurring the line between tag and packaging.In short, the form a tag takes is highly depe

46、ndant upon the application. Some tags need to be made to withstand high heat, moisture, and caustic chemicals, and so are encased in protective materials. Others are made to be cheap and disposable, such as “smart” labels. A “smart” label is just one form of a “smart” tag, in which an RFID tag is in

47、corporated into a paper packing label. While there are many applications in which RFID tags are anything but, the overall trend in the industry is towards this small, flat label that can be applied quickly and cheaply to a box or pallet.2.3 RFID INTERROGATORSAn RFID interrogator acts as a bridge bet

48、ween the RFID tag and the controller and has just a few basic functions.Read the data contents of an RFID tagWrite data to the tag (in the case of smart tags)Relay data to and from the controllerPower the tag (in the case of passive tags)RFID interrogators are essentially small computers. They are a

49、lso composed of roughly three parts: an antenna, an RF electronics module, which is respon-sible for communicating with the RFID tag, and a controller electronics module, which is responsible for communicating with the controller.In addition to performing the four basic functions above, more complex RFID interrogators are able to perform three more critical functions:implementing anti-collision measures to ensure simultaneous RW communication with many tags,authenticating tags to prevent fraud or unauthorized access to the system,data encryption to protect the integrity of data.2