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1419 1805Inventory and Monitoring
Using Radio Frequency Identification (RFID) for Monitoring Trees in the Forest:
State-of-the-Technology Investigation
United States Department of Agriculture
ForestService
National Technology & Development Program
April 2014
The information contained in this publication has been developed for the guidance of employees of the Forest Service, U.S. Department of Agriculture, its contractors, and cooperating Federal and State agencies. The Forest Service assumes no responsibility for the interpretation or use of this information by other than its own employees. The use of trade, firm, or corporation names is for the information and convenience of the reader. Such use does not constitute an official evaluation, conclusion, recommendation, endorsement, or approval of any product or service to the exclusion of others that may be suitable.
The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or part of an individual’s income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA’s TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410, or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer.
Using Radio Frequency Identification (RFID) for Monitoring Trees in the Forest: State-of-the-Technology Investigation
Rey Farve, Project LeaderForest ServiceNational Technology & Development CenterInventory and Monitoring Program
April 2014
i
TABLE OF CONTENTSI. INTRODUCTION ................................................................................................................................ 1 A. Background and Need ................................................................................................................ 1 1. FIA program ............................................................................................................................ 1 2.Needasidentifiedbyproposer ................................................................................................ 3
B.ObjectiveofInvestigation ............................................................................................................. 4
C. Technology Not Considered in the Investigation .......................................................................... 4 1. Barcode technology ................................................................................................................. 4
II. RFID TECHNOLOGY ......................................................................................................................... 4 A. Passive Tag – Active Reader ....................................................................................................... 5
B. Active Tag – Passive Reader ....................................................................................................... 6
C. Semi-Passive Tag – Active Reader .............................................................................................. 7
D.Application/UsageofRFIDTechnology ....................................................................................... 8 1.GeneraluseofRFID ................................................................................................................ 8 2.RFIDtechnologyuseinforestry .............................................................................................. 8
III. INVESTIGATION............................................................................................................................... 9 A. RFID Tags Investigated ................................................................................................................ 9 1. Semi-passive tags ................................................................................................................... 9 2. Passive tags ............................................................................................................................ 9
B. RFID Readers Investigated ........................................................................................................ 11
IV. FIELD TESTING THE MAXIMUM READ RANGE OF RFID TAGS AND READERS ................... 12 A. Indoor Test ................................................................................................................................. 12
B. Outdoor Test ............................................................................................................................... 13
V. CONCLUSIONS AND RECOMMENDATIONS ................................................................................ 15
VI. LITERATURE CITED...................................................................................................................... 17
APPENDIX ........................................................................................................................................... 19
A. PHOTOS OF RFID TAGS TESTED ................................................................................................ 21
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I. INTRODUCTIONForFiscalYear2013,GretchenNicholas(PacificNorthwestResearchStation,ForestInventoryandAnalysis(FIA)programmanager)submittedaproposaltotheNationalTechnologyandDevelopmentProgram’sInventoryandMonitoringSteeringCommitteetoinvestigatethestate-of-the-technologyofradiofrequencyidentification(RFID)foruseinrelocatingandmonitoringtreesintheforestenvironment.
RFIDtechnologyinvolvesawireless,non-contactsystemthatusesradiofrequencyelectromagneticfieldstotransferdatafromatag(attachedtoanobject)forautomaticidentificationand/ortracking.Thistechnology has advanced rapidly over the past decade.
TheproposalwasarequestfortheNationalTechnologyandDevelopmentProgramtoinvestigatewhether(ornot)RFIDtechnologyhasadvancedsuchthatitmightbeapractical,cost-effectivetoolfortheinventoryingandmonitoringoftreesonforestlands(especiallyfortheFIAprogram).
A. Background and Need
1. FIA programThe Forest Service’s Forest Inventory and Analysis (FIA) program providestheinformationneededtoassessAmerica’sforests.TheFIAprogramprovidesacontinuous,nationwideforestcensusthatprojectshowforestsarelikelytoappear10to50yearsinthefuture.ThisenablestheFIAprogramtoevaluatewhethercurrentforestmanagementpracticesaresustainableoverthelongterm.
Thenationwideforestcensusrequirescontinuous,periodiccollectionoffielddatatogeneratereportsonstatusandtrends:inforestareaandlocation;inthespecies,size,andhealthoftrees;intotaltreegrowth,mortality,andremovalsbyharvest;inwoodproductionandutilizationratesbyvariousproducts;andinforestlandownership.
TheFIAprogramismanagedwithintheForestService’sResearchandDevelopmentorganizationincooperationwithStateandPrivateForestryandNationalForestSystems.
2
Figure 1—FIA Program at PNW Research Station. See http://www.fs.fed.us/pnw/pubs/fia.pdf
Currently,forthenationalcensus,FIAmonumentsforestplotsandtreeswithmetaltags,whichassistinrelocating(revisiting)plots10yearslaterforremeasurement.Frequently,afterseveralyears,treeshaveconsumedthetagsortagsareotherwiselost.SinceRFIDtechnologyhasadvancedsignificantlyoverthepastfewyearsandisbeingusedinwiderapplications,theproposerspeculatedthatpassiveorsemi-passive RFID technology (see RFID technology discussion in section II) may have advanced to a pointthatthistechnologymightbeacost-effectivetooltotagtreesonaforestplot.
Iftreesonplotscouldbetaggedwithaninexpensive,durable,long-livedRFIDtagthatstoresall(ormost)ofthetree’spertinentdata(e.g.,location,species,height,diameter,crowncover,health,etc…),aresearcherwithanRFIDreadermighteasilyrelocatetreesonplots10yearslater.Additionally,ifthepreviousinformationaboutthetreecouldberetrievedeasilyandnew(remeasurement)datauploadedeasily,thetimeinvolvedinthedatacaptureprocess(i.e.,collectionofpreviousdataandrecordingofnewremeasurementdata)ontherevisitedplotscouldbegreatlyreduced.Thiswouldreducecostsassociatedwithdatacaptureperplot.
As such, the National Technology and Development Program’s Inventory and Monitoring Committee identifiedthescopeofthisinvestigationas:“Investigate and demonstrate an electronic tracking method for locating trees and plot centers over time.”
3
2.NeedasidentifiedbyproposerSanDimasstaffcontactedtheproposerinMarch2013todeterminethespecificneedsoftheFIAprogramfromRFIDtechnology.Table1identifiesparametersthatwouldbeconsideredideallysuitablefortheFIAprogramandparametersthatshouldbeconsideredunsuitable(notacceptable).TheparametersidentifiedasacceptablearethosethatmightbemoresuitableforotherforestersinResearchandDevelopmentortheNationalForestSystem(thatis,foresterswithintheagencythatarenotpartoftheFIAprogram).
Ideally,theproposerfeltthattheFIAprogramwouldbenefitfromRFIDtechnologythatallowedasurveyortobeabletorevisitaFIAforestplotcenterandquerytheinformationonallRFIDtagsthatwereattachedtotreesintheplotareaonthepreviousvisit(10yearsprior).Thereadrangeofthetagsshouldbe20feet(orgreater)forthetechnologybeasignificantimprovementoverthecurrentmethodofphysicallysearchingformetaltagsattachedtotrees.Also,theGPSlocationinformationstoredontheindividualtreetagsshouldenabletreestobemorereadilyrelocated.
Oncerevisited,thetreecouldberemeasured,andthisupdatedinformationuploadedtotheoriginaltag(orthetagcouldbereplaced,ifnecessary).Sinceseveralhundredtreesaremeasured(andremeasured)intheFIAprogram,tagswouldhavetobeinexpensiveandthetag-to-treeattachmentmustbesimpleandfast.
Table 1—Need/requirements of FIA of RFID technology for use in monitoring trees
Performance Requirement
Parameter IDEAL ACCEPTABLE* NOT ACCEPTABLE
Read range >20ft. 5-10ft. <3ft.Cost (per tag) < $ 0.10 $ 0.15 - $ 0.45 > $ 0.50Lifespan/durability 12+ yrs. 8-9 yrs. < 5 yrs.
Tag-to-tree attachment
Manual,simple,withlightweighttool Intermediate
Needs heavy tool(s),
complicated
ProgrammabilityFully and easily programmablein
thefield
Inoffice–(withsimpletreenumber) ---
Read accuracy 100% --- < 99%*RequirementsthatmightbemoreacceptabletootherforestersinR&Dand/orNFS
4
B. Objective of InvestigationTheobjectiveofthisstudyistoinvestigatethecurrentstateofRFIDtechnology–especiallyasitrelatestopractical,cost-effectiveusewithintheforestenvironment.TheinvestigationfocusesonneedsthattheFIAprogramconsideredasimportantformonitoringtrees.
SanDimasstaffenlistedthesupportofDonLimuti,electronicsengineer,NationalTechnologyandDevelopment Center, Missoula, MT. in the investigation.
C. Technology Not Considered in the Investigation 1. Barcode technologyBasedontheneedsidentifiedbytheproposer,barcodetechnologyisnotconsideredacceptable(orpracticable)forFIAuseonforestplotsforthefollowingreasons:
• Barcodesmustbeinthereader’sline-of-sight(i.e.,notobscuredbyotherobstacles/vegetation).
• Readersmustbe(atmost)withinafewfeetofthebarcode.
II. RFID TECHNOLOGY Unlessotherwisecited,mostoftheinformationinthissectionwasobtainedfrom:
en.wikipedia.org/wiki/RFID.
rfid.net/basics.
calpoly.edu/tutorial.htm.
Karygiannis et al. 2007.
RFIDtechnologyinvolvesawireless,non-contactsystemthatusesradio-frequencyelectromagneticfieldstotransferdatafromatag(attachedtoanobject)forautomaticidentificationand/ortracking.AtypicalRFIDsystemconsistsofaninterrogator(alsocalledareader),andatransponder(commonlyreferredtoasatag)(figure2).Thetagisusuallyattachedtoanobjectthatistobeidentified.
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READER
power for tag and reader
backscatterd signal
Tag
Figure 2—Typical RFID system consists of a reader and a tag. The reader sends radio waves to the tag that contains its identifying information. The tag responds to the reader with its information.
Radiotransmissionsareusedbythereadertosendaquerytothetagandbythetagtoreturnananswer,generallycontainingidentifyinginformation.Thereaderalsocanbeconnectedtoahostcomputer,whereinformationcanbeincorporatedintoadatabase.
ThethreebasictypesofRFIDsystemsare:(1)PassiveTags–ActiveReaders;(2)ActiveTags–PassiveReaders;and(3)anintermediatesystemofSemi-passiveTags–ActiveReaders.
ThefollowingdiscussionistheresultofabriefliteraturesearchthatstaffconductedonRFIDtechnology.
A. Passive Tag – Active Reader Passivetagshavenopoweroftheirown;instead,allthepowerneededtooperatethetagisderivedfromtheradiosignalssentbythereader.Furthermore,passivetagshavenoconventionalradiotransmitterand,assuch,cannotcreatetheirownsignal.Instead,theyvarytheelectricalloadattachedtotheantennainordertovarythesignalreflectedfromtheantenna,somewhatanalogoustousingamovablemirrortosendasignalbyreflectingthelightofthesuntowardsawatcher.Thistechniqueisknownasbackscattercommunications.Backscattercommunicationsalsorequirethatthetagandreaderbeincloseproximity(withinafewfeet)ofeachotherwhenthetransmittedradiowavesarelowfrequency(LF)orhighfrequency(HF).Withtheemergingtechnologythattransmitultra-highfrequency(UHF)radiowaves,longerreadrangesarebecomingpossible1;someUHFRFIDmanufacturersclaimreadrangesaslongas15to20feet.Sincemetalandwater(ormoisture)tendtoabsorbUHFwaves,considertheirpresencewhenevaluatingUHFtagsreadranges.
1ForadiscussionofthedifferencesbetweenHFandUHFRFID,seeIntermecTechnologiesCorporation(2007).
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Passivetagsoftenareextremelysimpledevices(figure3).Thetypicalstructureconsistsofaplasticsubstrateorinlay,aprintedoretchedmetalantenna,andasingleintegratedcircuit.Asaconsequence,passivetagscanbemuchsmallerandlessexpensivethanothertypesofradiodevices.AUHFpassivetagwithanantennacanbepurchasedinbulkfornickelspertag.
READER
power for tag and reader
backscatterd signal
TagBattery/power
Passive Tag/Active Reader Less than $ 0.10
Last 10 -20 yrs
1 in. to 20 ft.Read Range
Figure 3—RFID system that consists of a passive (non-powered) tag and an active (powered) reader.
Apassivetagrequiresnomaintenance,andhasalonglifetime,limitedbydegradationofthetagmaterialsratherthanbatteryusage.Itisreasonabletoexpectthatinmanyenvironmentspassivetagswillbereadablefor10to20years.
B. Active Tag – Passive ReaderThisRFIDsystemistheoppositeoftheonedescribedinsectionII.A.IntheActiveTag–PassiveReadersystem,thetagispoweredandthereaderhasnopower(figure4).Inessence,anactiveRFIDtagisequippedwithitsownradiotransmitter,suchasacellphoneorWiFiclient.
Activetagsuseconventionalcircuitryfortransmissionandreceptionwithreadrangeandreliabilitysimilartotheperformanceofotherradios.Assuch,readrangesofhundredsofmeterstokilometers(miles)areachievable,andtagscanbereaddespitesubstantialobstructionsbetweenthetagandreader.
Withimprovedreadrangeandreliabilitycomesincreasedcost,size(circuitcomplexity),andmaintenancerequirements.Activetagscostmorethan$20each;somecostasmuchas$100eachandaredesignedfortrackinghigh-valueassets.
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Tag
battery
Active Tag /Passive Reader
READERTransmitted signal
from tag
$20.00 - $100 .00Last 3- 5 yrs
> 1500 ft Read Range
Figure 4—RFID system that consists of an active (powered) tag and a passive (non-powered) reader.
Thistechnologyisnotpractical(orcost-effective)fortheneedsidentifiedinthisinvestigationandwillnotbeinvestigated/evaluatedfurther.ReadersinterestedinmoredetailsonActiveTagRFIDtechnologyshouldseethereferences/linksprovidedatthebeginningofthissection.
C. Semi-Passive Tag – Active ReaderThisRFIDsystemisintermediatebetweenthetwosystemsdiscussedinsectionsII.AandII.B.IntheSemi-Passivetag–ActiveReaderSystem,thereaderispoweredandthetaghasabatterytopowerthetag’scircuitry;thetag,however,stillemploysbackscatteringorloadmodulationtocommunicatewiththereader(figure5).
Semi-passivetagsrequirethatthereadersignalbelargeenoughtodecipherbutdoesnotneedtoextractpowertorunthetag’scircuitry.Therefore,thereadrangeisnotlimitedtoafewfeet(aswithapassivetag).Thereadrangeofsemi-passivetagsusuallyislimitedbytherapiddecreaseinthereadersignal;however,high-qualityreceiverscanachievereadrangesontheorderof300feetinunobstructedareas.
Inadditiontolongerrange,semi-passivetagsprovidemuchbetterreliabilityatshortranges.Apassivetagatseveralfeetfromareadermightnotreadthetagifthetransmissionpath(oftheradiowaves)fromtagtoreaderisblockedbyanobstacle.Asemi-passivetagatasimilardistanceisoftenbettertodecipher and reply to the reader’s signal.
Adownsideofsemi-passivetagsisthattheyaremoreexpensivethanpassivetags;furthermore,theirapplicabilityislimitedbybatterylife.Manufacturersofsemi-passivetagstrytoensurethatmostofthecircuitryisswitchedoffexceptwhenthetagisbeingqueriedbyareader;batterylifeisstillgenerallylimitedtoonlyafewyears.
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READER
power for signal (from reader )
backscatterd signal
Tag
batteryBattery /power
Semi -passive Tag /Active Reader
$3.00 - $10 .00Last 3-5 yrs
< 300 ft Read Range
Tag circuitry powered by battery
Figure 5—RFID system that consists of a semi-active (powered) tag and an active (powered) reader.
D. Application/Usage of RFID Technology 1.GeneraluseofRFIDRFIDisusedinnumerousapplicationsanditisprojectedtobecomemorewidespreadinthefuture.ForageneraldiscussionofRFIDhistory,usage,andcostseeRoberts(2006)andZhuetal.(2012).
Ferreretal.(2010)provideadetaileddiscussionofhowRFIDcanbeusedtoenhanceawidevarietyofservicedeliveryoperations(e.g.,freewaytollcollection,librarymaterialtracking,hospitalpatienttracking, cargo tracking, retail cashless payment, and several others). They reported that most industriesbenefitedbyreplacementoflaborthroughautomation,cycletimereductions,enablingself-service, and/or inventory control/loss prevention.
ForadiscussionofRFIDuse(andchallengestousage)intheagricultureindustryseeRuis-GarciaandLunaei (2011).
2.RFIDtechnologyuseinforestryAccordingtoourliteraturereview,thesuggestedapplicationofRFIDforforestryisfortrackinglogsthroughtheforestrysupplychainandisreportedbyEuropeanforesters(GermanyandFinland).KortenandKaul(2008)werethefirsttoreportonthefeasibilityofusingapassiveRFIDtagtotracklogsastheymovedthroughthesupplychain.However,theshortreadrangeoftheHFtagsusedinthepilotstudy(6inchesto1foot)madereadingtagsasignificantchallenge.
Hakiietal.(2010)andBjorketal.(2010)reportonpassiveUHFRFIDtagsthatwereattachedtothebuttendofcutlogs.The6-footreadrangeoftheUHFtagallowedlogstobetrackedbyareaderattachedtotheharvesterandtworeaderslocatedatthemill(inalogsortingareaandalogsawingarea)todocumentsupply-chainperformance.
ForestersfromAsia(MalaysiaandSouthKorea)haveperformedpilotstudiesusingRFIDtagsattachedtotreestotestthefeasibilityofusingthetechnologyformonitoringtrees.Mohamedetal.(2009)
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conductedaproof-of-concept-likestudythatreportedonthebenefitsandchallengesofusingRFIDinaforestsetting.Jungetal.(2009)attachedvarioussizedUHFRFIDtagstotreesandcomparedmaximumreaddistanceunderdifferentenvironmentalconditions.Ofthe15differenttagstheytested,themaximumreaddistancewasnomorethan5feet.Largertagstendedtoperformbetterthansmallertagsanddampweathertendedtoaffectreadrange.
III. INVESTIGATION BasedonourreviewofRFIDtechnologyliterature(sectionII),wefeltthatpassiveUHFtagsmightprovideareasonablesolutiontomeetseveralofFIA’sneeds.We,therefore,decidedtoinvestigateseveralmanufacturersofRFIDtechnologythatuseUHFtogainadditionalinformationonthecapabilitiesofpassivetagsandreaders.
Thiswasnotacomprehensive,exhaustiveinvestigation;itwasareasonablesearchofpotentialvendorstogetasenseofwhatthecurrentstate-of-RFID-technology(usingUHF)isrelativetouseforinventoryandmonitoringoftreesintheforestenvironment.WecontactedseveralRFIDmanufacturerstodetermineiftheyhadaproductthatmightmeettheneedsidentifiedinsectionI.A.2,table1.
Don Limuti, electronics engineer, National Technology and Development Center, Missoula, MT conducted the investigation.
A. RFID Tags Investigated 1. Semi-passive tagsDuringthecourseoftheinvestigation,wewereabletoconfirmouroriginalunderstandingofthebenefitsandshortcomingsofsemi-passivetags(sectionII.C).Semi-passivetagshavemuchlongerreadrangesthanpassivetags,butthecurrentcostandshortlifespanofsemi-passivetagsmakethemunacceptableasatoolfortheFIAprogramandmostlikelymakethemimpractical(ornotcosteffective)forotherpotentialuserswithintheNationalForestSystem.Wedidnotinvestigatesemi-passivetagsfurther.
2. Passive tagsSincewesuspectedthatpassivetagsmightprovideareasonablesolutiontomeettheidentifiedneeds,theinvestigationfocusedonthistechnology.Earlyintheinvestigation,itbecameobviousthatonlytagsthatutilizedUHFradiowavestotransmitdatawouldbecapableofprovidingreadrangesclosetothedistancesofinterest(i.e.,>20feet).Assuch,theinvestigationfocusedonlyonpassiveUHFtags.
10
WecontactedeightRFIDmanufacturers(seetable2)duringMay–September2013toinquireabouttheirRFIDtags,especiallytheirabilitytomeetouridentifiedneeds(table1)2.BySeptember2013,wehadacquiredsampletagsfortestingfromallmanufacturers.Thepassivetagsprovidedbythemanufacturerscameinmanyshapesandsizes.Sincewewereprimarilyinterestedinthereadrangeofthetags,wewerenotparticularlyconcernedwiththeformfactor(i.e.,packaging,physicalshape,orsize)ofthetag.(SeeappendixAforphotosofseveralofthetagstested.)Inthecourseoftheinvestigation,weperiodicallyaskedthemanufacturersaboutcost.Weneverrequestedaformalquotefromthemanufacturers,butourgeneralsensewasthat$0.45/tag(orgreater)foranorderof100,000+wasprobablymostmanufacturersnegotiatingstartingpoint.
Table 2. RFID manufactures that were contacted for the investigation and the number of tags they provided for testing
RFIDManufacturer Website PointofContact #ofTags
Provided
SAG www.sag.com.twDaniel Yeh danielyeh@sag.
com.tw 4
ZEBRA www.zebra.comStuart_Garney@Identisys.
comwww.identisys.com
3
THINKIFY www.thinkifyit.com
Melissa Beagle, [email protected]
6
CONFIDEX www.confidex.com
Eric [email protected] 2
FRICK www.fricknet.comBrentHowellBrent.
VIZINEXRFID
www.vizinexrfid.com
2
HIDGlobalCorp.
www.hidglobal.com
David [email protected] 3
uGROKit www.ugrokit.comLaura Sankey
Total 35
On5-6November2013,wetestedthetagsattheNationalTechnology&DevelopmentCenter,Missoula, MT (see discussion in section IV).
2 WeconsideredFIAsidentifiedneedforlongreadrangesandlowcost/tagasthemorecrucialneeds.Wefeltifthoseneedscouldnotbesatisfied,FIAwouldnotbeinterestedinwhether(ornot)RFIDtechnologymettheotheridentifiedneeds.
11
B. RFID Readers InvestigatedTobeapracticalfieldtool,wefeltthataRFIDreadershouldbelightweight,rugged,andwaterproof.TheRFIDreaderalsoshouldallowforwirelessconnectivitytoalaptopandhaveabout0.5wattsoftransmission(output)powertoprovideforalongreadrange.
Duringthecourseoftheinvestigation,weidentifiedtwoRFIDreadersthatmetmostofthoseparameters:ThinkifyUHFReaderandtheuGROKitReader.ThemanufacturersoftheseRFIDreadersloaned us the devices to use in testing the passive tags.
TheThinkifyRFIDreaderisattachedto(integratedwith)anATid–AT-570mobilecomputer (figure6).Thereaderhas0.8wattsoftransmissionpower.TheuGROKit Reader system uses a smartphone (iOS or Android) attached to a RFID reader (called a Grokker)thatoperateswith0.4wattsoftransmissionpower(figure7).
Figure 6—Thinkify RFID reader (attached to ATiD, AT-570 mobile computer). Top = top view; Bottom = front view
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Figure 7—uGROKit RFID reader (Grokker) attached to mobile phone.
IV. FIELD TESTING THE MAXIMUM READ RANGE OF RFID TAGS AND READERSWetestedthereadrangeoftheRFIDtagsandreadersatMissoula,MT,on5–6November2013.On5NovemberinaconferenceroomattheMissoulaCenterwetestedallRFIDtagsfortheirmaximumreadrange.Sinceweconsideredareadrangeof15feettobeatthelowerendoftheFIAsneed,wefeltthatanytagsthatconsistentlyhad,atleast,thatreadrangewouldbetestedoutdoorstoo. A. Indoor TestWetestedthetagsbyattachingtheRFIDtags(ofagivenmanufacturer)totheconferenceroomwall(usingmaskingtape)andusedtheThinkifyanduGROKitRFIDreaderstodeterminethemaximumreadrange(figure8).Westartedthetestbyreadingthetagswithonereaderatadistanceof2feet.(Note:Thereaderwasrotatedinalldirectionstoobtainatagreading.)From2feetwebackedawayfromthewall(tag)at3-footincrementsuntilwewereattheotherendoftheroom(27feet).ThenwetestedthesametagswiththeotherRFIDreader.Wethenrepeatedtheprocesswithanothermanufacturer’stags.
Figure 8—Indoor testing of maximum read range of uGROKit tags.
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Theresultsofthemaximumreadrangetestareshownintable3.
Table 3—Indoor read ranges of 35 passive RFID tags tested in the study
Thereadrangeofthetagswas2feetto27feet(i.e.,thelengthoftheroom).TheGrokker(i.e.,theuGROKitreader)consistentlyreadfurtherthantheThinkifyreader.
Fromthisindoortest,weselected12tags(shadedingreenintable3)foroutdoortesting.Ingeneral,these12tagsconsistentlyhadareadrangeof15feet(ormore)frombothreaders. B. Outdoor Test Weconductedtheoutdoortestofthe12selectedtagsindividuallyinthefrontparkingareaoftheMissoulaCenter.Weattachedeachtagtoacottonwoodtree(11inchesindiameter).Aswiththeindoortest,westartedthetestbyreadingthetagwithonereaderatadistanceof2feet,facingthedirection
14
ofthetag(figure9).(Note:Asintheindoortest,thereaderwasrotatedinalldirectionstoobtainatagreading.)From2feetwebackedawayfromthetree(tag)at3-footincrements(butalwaysdirectlyfacingthetag)untilwecouldnolongerreadthetag.ThesametagwastestedwiththeotherRFIDreader.
Figure 9—Testing read range of RFID tags outdoors. Top - RFID tag taped to cottonwood tree. Bottom - Reading a RFID tag several feet from tree.
Theresultsofthemaximumreadrangetestareshowninfigure10.Noneofthetagsreadfartherthan15feet.Fourofthe12tagshadreadrangesof12to15feet.Themanufacturersofthefourtagswere:Vizinex(#90E785);Zebra(#221605);andThinkify(#204B61and#10E1FC).
Wealsotestedreadingthetagsat45degreesand90degreeswithin6feetofthetree,butreceivedinconsistentreadings.Assuch,wedecidednottosystematicallytestreadingtagsinthismanner.
15
Figure 10—Outdoor read ranges of the 12 passive RFID tags tested in the study – using the uGROKit and Thinkify RFID Readers. The four tags above the red line had maximum read ranges of 12 to 15 feet.
V. CONCLUSIONS AND RECOMMENDATIONS AsstatedinsectionI.B,theobjectiveofthisstudywastoinvestigatethecurrentstateofRFIDTechnology–especiallyasitrelatestopractical,cost-effectiveusewithintheforestenvironment. WedeterminedthatthecurrentstateofRFIDtechnologydoesnotmeetthemostcrucialneeds(i.e.,lowcostandlongreadrange)identifiedbytheproposer.NoneoftheRFIDtagsthatwetestedoutdoorshadamaximumreadrangeofmorethan15feet.Also,manufacturersindicatethatthelikelycost/tagwouldbe$0.45/tag(orgreater)for100,000+tags.
IfthecostofpassiveUHFRFIDtagscontinuestodeclineandthereadrangeimproves,thistechnologymaybecomeanincreasinglyattractiveoptionforinventoryingandmonitoringassetsoutdoors.
WediddeterminethatsomemanufacturershaveRFIDtagsthatprovidefairlylongoutdoorreadranges(15feet).Somemanufacturers(Vizinexinparticular)toldusthattheywereworkingactivelyonimprovingthereadrangeoftheirpassiveUHFtags.Also,moreexpensiveRFIDreaders(withmoreoutputpower)mightincreaseoutdoorreadranges.Assuch,amorefocusedcollaborationwithaForestServicesponsor(e.g.,FIA)andaspecificmanufacturer(orafewmanufacturers)mightleadtothedevelopmentofaninexpensivetagwithalongerreadrangeandasuitableformfactor.
17
VI. LITERATURE CITEDBjork,A.;Erlandsson,M.;Hakli,J.;Jaakkola,K.;Nilsson,A.;Nummila,K.;Puntanen,V,;Sirkka,A.2010.MonitoringenvironmentalperformanceoftheforestrysupplychainusingRFID.CommutersinIndustry. 62: 830-841.
Ferrer,G.;Dew,N.;Apte,U.2010.WhenisRFIDrightforyourservice.Int.Jour.Prod.Economics.124:414-425.
Ha¨kli,J.;Jaakkola,K.;Pursula,P.;Huusko,M.;Nummila,K.2010.UHFRFIDbasedtrackingoflogsintheforestindustry.In:ProceedingsoftheIEEEconferenceonRFID(IEEERFID2010),April(2010).245–251.
Jung,T.-W.;Koo,J-H.;Kim,K-M,;Pyeon,M-W.2009.ResearchonRFIDsystemrecognitiontestundertheforestryenvironmentfortreemanagement.In:FifthInternationalJointConferenceonINC,IMS,andIDC, Seoul, (2009). 1180–1184.
IntermecTechnologiesCorporation.2007.UHFvs.HFRFID:newinsightsontheolddebate.WhitePaper.Downloadedon8/26/2013at http://www.intermec.com/public-files/white-papers/en/UHFvs.HF_RFID_wp.pdf.
Karygiannis,T.;Eydt,B.;Barber,G.;Bunn,L.;Phillips,T.2007.Guidelinesforsecuringradiofrequencyidentification(RFID)systems.RecommendationsoftheNationalInstituteofStandardsandTechnology.NISTSpecialPublication800-98.
Korten,S.;Kaul,C.2008.ApplicationofRFID(RadioFrequencyIdentification)intheTimberSupplyChain.CroatianJ.ForestEngineering.29:85-94.
Mohamed,N.;Garoot,A.H.;Hazza,Z.M.2009.AcasestudyonimpactofRFIDadoptionintreeinventorymanagement.In:2ndIEEEInternationalConferenceonComputerScienceandInformationTechnology(ICCSIT),Beijing,(2009).624–628.
Roberts,C.M.2006.Radiofrequencyidentification(RFID).Computers&Security.25:18-26.
Ruiz-Garcia,L.;Lunadei,L.2011.TheroleofRFIDinagriculture:applications,limitationsandchallenges.ComputersandElectronicsinAgriculture.79:42-50.
Zhu,X.;Mukhopadhyay,S.K.;Kurata,H.2012.AreviewofRFIDanditsmanagerialapplicationsindifferentindustries.Jour.Eng.&Technol.Manage.29:152-167.
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APPENDIX A. PHOTOS OF RFID TAGS TESTED
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FRICK Tags SAG Tags
THINKIFYTags VIZINEXTags
uGROKit Tags HIDTags
