Applicability of RFID in the prognostics of logistic systems

Applicability

of RFID

in

the prognostics

of

logistic

s

stemis

A.M. L6pez De La Cruz

Section ofTransport

Engineering and Logistics Delft University of Technology

Mekelweg 2, 2628 CD Delft The Netherlands

Email: a.m.lopezdelacruz@tudelft.nl

H.P.M. Veeke

Section of Production Engineering and Logistics Delft University of Technology

Mekelweg 2, 2628 CD Delft The Netherlands Email: h.p.m.veeke@tudelft.nl

G. Lodewijks

Section ofTransport Engineering and Logistics Delft University of Technology

Mekelweg 2, 2628 CD Delft The Netherlands Email: g.lodewijks@tudelft.nl

Abstract- The objective of this paper is to investigate the ap-plicability of RFID in prognostic logistics. Starting from a general introduction of prognostic logistics, the system structure, and technical requirements are discussed. Based on this discussion the issues and concerns regarding the applicability of RFID in prognostic logistics are presented. Finally we summarized the benefits, requirements, inhibitors, opportunities and facilitators of RFID inprognostic logistics.

Index Terms- Prognostic logistics, RFID.

I. INTRODUCTION

Logistic visibilitycanbe definedastheextent towhich the position or location of an object, service or information and its status are known in a logistic system [1]. Visibility enables all actors in the logistic system to easily manage all

processes and activities while increasing productivity, quality and control.

The technological improvements have made it possible to

benefit from faster andmore accuratetechnologies that provide datacontinuously and in real time. One of these technologies is RadioFrequency Identification (RFID). RFID is an automatic identification (Auto-id) technology that enables data capture

and identification without contact or line of sight. RFID has

generated largeinterest from different research communities in thepastfew years. Notonly RFIDprovides a systemcapable of tracking and tracing valuable items through the supply

chain,butalso, RFIDis seen as atechnologythatcanprovide

a costeffective solution forlarge scalesensordeployment [2].

RFID systems can be installed in large scale systems to

provideinformation aboutobjectsandequipment continuously

and in real time. These characteristics; among many others,

makeRFID asuitable technologyto supportprognostic logis-tics. Prognostic logistics appliesreliable realtimeinformation in orderto enable accurate prediction on the future state ofa system [3]. This information of the futurestatus of thesystem can be used to support control decisions.

Prognostic logistics have two main components, the infor-mation system and the logistic model.

This research was sponsored by the Transumo Research Program

(www.transumo.nl)

INFORMATION LOGISTIC r/ SYTEM MODEL

Fig. 1. Prognostic logistics structure.

The information system is in charge of acquiring specific data and transform it into useful information. The logistic model uses the derived information to support decisions and perform predictions about the future condition of a system.

This paperfocuses onthe information system ofa prognostic logistics system and the use of RFID as a data acquisition

system.

In order to study in more detail the applicability of RFID

in prognostic logistics, the rest of this paper is organized

as follows: Section II will explain what the requirements

and restrictions for data capture andprocessing inprognostic

logistics are. Section III willpresent the technical challenges ofRFID to be used in prognostic logistics. Section IV will summarized the benefits, requirements, inhibitors,

opportuni-ties and facilitators ofRFIDinprognostic logistics.InSection

V conclusions are presented.

II. INFORMATIONSYSTEM INPROGNOSTIC LOGISTICS

Thereliability of the predictions made in prognostic logis-tics highly depends on the quality of the data acquired. The information systemis in charge of acquiring, communicating andprocessing the data so that itcan be used for the logistic

model. The data acquisition is automated and needs to be donefast, continuously, inreal time and almost without human involvement in order toreduce errors.

The level of datacapturedependsonthe desiredprognostics

capability. Firms have theopportunitytochooseatwhatstages

oftheirlogistic systemcontinuousmonitoring, and acquisition

of information is vital for the logistic system management.

Furthermore, companies will decide what additional datamust

be collected for specific cases. This infrastructure will

vide the needed information to accurately anticipate logistic requirements, and will function as a flexible network on the base of essential information [4].

The information system should support data capture not

only about the product but also information about equipment, environment condition andprocesses. The level of datacapture

of the information system is application dependant. However, no matter the application, it is desired for the information

system to support alarge flow of information and be scalable; especially in cases of large and difficult deployment condi-tions.

The accuracy of the prognostic logistics network relies on

the quality of the data captured. The quality depends on the

system used todo such atask. Sensors, wireless communica-tion, networking and processing are basic components of the informationsystem. An overview of emerging technologies to

be used in intelligent infrastructures like prognostic logistics is available in [2]. Adescription of the characteristic of these technologies is given.

A. Sensors

Sensors are in charge of data acquisition at different levels of the application environment; from temperature sensing of bearings until the tracking and tracing of pallets and

contain-ers. Inthe market therealready exist differenttypesofsensors

capable ofcapturedifferent sortof data. However, this typeof

sensors canbe highly expensive, and difficultto fit andadapt in situations with limited space and hard working conditions; reducing the possibility to monitor and acquire data.

New sensors areexpectedto becomean integral partof the objects, and will be required to operate on the atomic scale. Furthermore, suchsensors will havetocommunicate with each other over largeareas using multi-hop routing algorithms [5], [6], andenergy efficientprotocols.

B. Wireless networks

Wireless networks and mobile communication give auton-omy tothe devices and enableubiquitous communication with

objectsonthemove; gathering sensorinformation whenever is required. Telecommunications research has been focusing on

4Gand MANETsystems.4Gsystemswillbegin by integrating

the existing technologies, 3G, digital audio broadcast, and wireless LAN, into a heterogenous wireless networks to

pro-videaccess to anincreasingrangeof services [7], [8]. MANET

systems (Mobile ad hoc network) is a collection of mobile

computing devices that cooperate toform adynamic network without fixed infrastructure. One of the main problems in MANETnetworks is the quality of service (QoS) since there isnoreal infrastructure and therouting of information is more

difficult due tothe dynamic connectivity.

C. Dataprocessing

Data mining and processing should evolve to applications thatcanignorenetworktopologyand focusonthe information sensed by thousands of sensors [2]. The information will be the primer focus of the applications not the location of

the sensor itself. It is vital for the successful application of such a pervasive systems that the location of sensors and the topology used to acquire information be of no concern for the application. Thegoal is an ubiquitous system to sensethe needed information no matterthe location.

III. TECHNICAL CHALLENGES OFRFID INPROGNOSTIC LOGISTICS

In [1], it was mentioned that the reliability of UHF RFID

depends on the readability of the tags attached the objects.

It was mentioned some of the most important technological challenges of passive UHF RFID systems i.e. tag antenna

size and shape, anti-collision protocols, reading rate, among

others. Inthispaper weextend theanalysis presented in [1]to

activeRFIDtags. Thistype oftagshave batteries andsupport

active communication. This characteristic makes active RFID a suitable candidate to be used as adata capture system in a

prognostic logistic infrastructure.

Taking into account the requirements of the information

systeminprognostic logistics, the technological challenges of active RFID arehighlighted.

A. Energy

efficiency

Activetags run on battery. The energy resource of the tags

determines their lifetime. Since thedeployments of suchatags

inprognosticlogistics willnotallowtorechargeorchange the batteries of thousands of nodes, the use ofenergy should be made as efficient aspossible for everynode and newways of

energyharvesting should be investigated for large deployment applications.

B. Low cost

Networks withlarge deploymentshould becheap. Theprice

onthetags should achieveanacceptablelevel. Themonitoring

system can not be equal or more expensive than the system

itself.

C. Distributed sensing

The use of large deployments of sensors facilitates the

capture of diverse information. Distribution sensing provides

robustness to environmental obstacles, and redundancy on

crucial information.

D. Wireless

Many ofapplicationsneither have the needed infrastructure forcommunications, nor want to createsuchan infrastructure. Theuse of wireless opensthepossibility to usethe sametags notonly for dedicated studies buttowiden thepossibilitiesfor different data capture usingthe same communication nodes.

E. Multi hop

The communication between nodes should be done using

F Distributedprocessing

The use of distributed processing reduces the amount of data that needs to be transmitted to a central system. Each node should be capable of filtering and aggregating data to

transform itto useful information.

Although active RFID can be seen as the logical choice when continuous monitoring and active communication are

needed, passive RFID should not be ruled out. Passive tech-nology has limitations regarding data capture and sensing, and the tags are limited to report the current status when they are reached by the reader. However, in [9] a series of passive tags and sensors applications involving monitoring

of physical parameters, automatic product tamper detection, and bacterial contamination has been documented. In several

cases, neither of both technologies offers acomplete solution for an intelligent infrastructure system, rather, the active and passive technologies can be seen as complementary, offering together the possibility to ensure visibility and support real time information incomplex logistic systems.

IV. APPLICABILITYOF RFID INPROGNOSTIC LOGISTICS

The application ofRFID inprognostic logistics is going to

be analyzed by looking atthe following evaluation points:

. Direct benefits

. Requirements

. Inhibitors

. Opportunities

. Facilitators

We furtherexplore each of these below. A. DirectBenefits

Investing in a large deployment of information technology

at different levels in logistic systems is expected to facilitate the planing, control and schedule of activities. Some of the applications where theuseoftechnologies likeRFIDimproves tracking and tracing, monitoring of pieces and equipment and optimized transport of perishable goods are mentioned on

[3]. These applications explore the various possibilities and

advantages ofusing real time information.

The information resulting from the acquired data can be usedtoupdate dynamic algorithmstosupportdecisionmaking

and control of activities. It can be expected that the gained visibility and added functionalitiesresulting fromusing RFID

will be reflected in an increased ofefficiency throughout the whole logistic system. With the continuous data capture, it is

possible to retrieve information about product availability in

just seconds, reducingthe orderprocessingtime andincreasing

on-time deliveries. Product demand can be measured in a

daily basis, optimizing replenishment policies and improving

coordination between supply and demand. Detailed infor-mation about processes and equipment status provides the logistic management with the necessary tools to reduce lead

times, increase security, and reduce inventory levels.With the

gathered information it is possible to know current inventory

levels decreasing throughput time and increasing productivity.

B. Requirements

One of the major requirements for RFID in prognostic logistics is tobe abletoacquire specific data. This meansthat

RFID (passive and active) should support sensors, andtag to tagcommunication. Also, RFIDneedstoresolve technological issues that still donotallow 100% reliability of thesystem [2],

[1].

Beyond the technological improvements RFID still needs

to go through, a robust logistic infrastructure also should be developed. This will allow the collection of real time information from anywhere in the logistic system.Usually, the shipment of goods involves multiple manufactures, multiple transportation companies and so on. Therefore, the RFID

infrastructure available to track every item is a requirement for a reallarge scale and pervasive deployment.

As RFID becomes ubiquitous, the communication

infras-tructureisrequiredtoco-exist with other wirelesstechnologies that have overlapping and complementary performance speci-fications [10]. It is expected that technological developments will look at a combination of different wireless technologies i.e. RFID, Bluetooth, WLAN, in ordertoprovide cost reduc-tion and enhanced quality of service.

Another requirement will be training and employment of specialize ICT experts. They will be in charge of monitoring andmanaging the overall prognostic logistics infrastructure. C. Inhibitors

Using a large deployment ofRFID can be constrained by

two major inhibitors: the security and thecosts.

The protocols used for communication may incorporate securitymeasuressuchencryptiontoencode theidentity of the

user and the transaction. There isatrade-off between security andperformance. The shorter the key used for encryption, the easier it is to compromise the privacy of the communication [2]. There have already been reports of tag codes being broken [11], [12], [13]. With this fear, the spread used of this technology is compromised, and it is led to consumer

product manufactures the responsibility to deal with privacy and security issues.

Thecostsinvolved inalarge deployment ofRFID arerather high. There are two main cost elements: the manufacturing

costs and the customization costs. The manufacturing costs can be broken down as follows [14]:

. Chip Usually in the range of US$0.25-0.35 a piece in

quantities of 1-10 million.

. Inlay/ Substrate withantenna from US$0.02 to US$0.10

andmore depending on the size and the material used.

. Assembly around US$0.02 to US$0.04

. Licensing from 5-7.5% of the hardware value

The above correspond to the costs for passive RFID tags.

Active tags are more expensive than the passive ones; they value canbe anywhere from

US$20-US$100

The large deployment ofRFID requires considerable

com-puting power and system integration to collect and process

was mentioned the need to perform readability tests before applying RFID to a specific application. The goal of these

tests is to characterize RFID and determine its compatibility with theapplication. Because RFIDneedstobe customized for its specific working and application purposes, the successful operation ofan RFIDsystemwill havetoincur in considerable

system design, customization and configuration costs. D. Opportunities

Toincrease the quality, productivity, and agility of complex logistic systemscompanies experiment withRFID technology

as an Auto-ID tool to increase the visibility of the objects, services, and information involved in their processes. The opportunities these systems for logistic systems are [1]:

. Serialize data; inventory control, reduction of loss,

re-duced carrying costs.

. Reduce human intervention; reduced errors which

pro-duce repro-duced costs, faster throughput and reduced

dam-age andreturns.

. Increase throughput in logistic systems; with RFID it is possible to read hundreds of objects almost simultane-ously.

* Allow real time informationflow; deliveronpromises,

re-duce errors, increase customer loyalty, optimize material

use.

. Increase item security; improve delivery and control, decrease counterfeiting and shrinkage.

. Optimize maintenance procedures; withRFIDispossible

tomonitor the health ofpieces and equipment

E. Facilitators

The initial facilitators ofRFID deployment were the

man-dates that Wal-Mart and the United State Department of Defense placed on theirs vendors. Wal-Mart asked that its

top 100 suppliers to have incorporated RFID labels in all their shipments for the beginnings of 2005. These demands

pushedthe introduction ofRFID, and the creation of standards

to ensure inter-operability among tags and readers, reduce prices, and facilitate the growth of the RFID global market [16]. Although RFID still needs to solve the challenge of

standardization, the movement toward achieving standards is

a facilitator to the future development ofRFID in prognostic

logistics. Until these standards are finalize, there is a risk ofnon-compliance associated with any solution implemented

[17].

V. CONCLUSION

In section II the information system ofprognostic logistics

wasdescribed.Anumber of characteristicswereidentified that

composed the information system ofprognostic logistics. In

general it can be said that the structure of the information

system depends onthe application environment, and the char-acteristics of the datacapture system used.

There are plenty of investigations at the momenttrying to

research whatRFID cando, andtryingtodevelop applications

for RFID in logistic systems. However, the configuration of

TABLE I

EVALUATIONPARAMETERFOR THE APPLICABILITY OFRFIDIN PROGNOSTIC LOGISTICS

Evaluation RFIDin Prognostic parameter Logistics Direct Benefits Real time information

Optimization of Resources Requirements Technologicalimprovements

Inhibitors Opportunities

Facilitators

Infrastructure development Co-exits with Wireless systems

Specialize ICT expertise Security

Costs Serialized data Reduce human error

Increasethroughput Real time informationflow

Increaseitem security

Optimizemaintenance RFIDMandates

Standardization

RFID as a prognostic logistics tool depends on the network configuration. Furthermore, in Section IV an analysis was

presented where the direct benefits, requirements, inhibitors, opportunities and facilitators of using RFID in prognostic

logistics were defined. From this analysis, it can be said that

at the moment, RFID provides interesting advantages for the implementation in prognostic logistics. However, a series of technological issues, standards issues and costs issues should be resolved before RFID can befully realized.

The technological challenges of RFID were exposed in Section III and in [1]. These technological issues do not

allow RFID to be a 100% reliable system. Although 100% reliability is desirable, the reliability measure depends onthe application, and the sensitivity of the logistic system to a

disruption in objects visibility. Continuous research focusing

onthe fundamental characteristics ofRFID canhelptoidentify

problems and provide answers to maximize the performance and increaseprobability of successful readings.

As technological issues are resolved andmore effort isput

into RFID research and development; the resolution ofcosts

issues will remain the biggest impediment forRFID adoption.

But once these issues are resolved RFID will become a

significant opportunitytotransformlogisticsystemtechnically

and operationally and to use as a data capture tool in the information system ofprognostic logistics.

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