2024年4月29日发(作者:)

Apr.2019TransactionsofNanjingUniversityofAeronauticsandAstronauticsVol.36No.2

AGenericPlug‑and‑PlayNavigationFusionStrategyfor

LandVehiclesinGNSS‑DeniedEnvironment

LAIJizhou

*

,BAIShiyu,XUXiaowei,LÜPin

KeyLaboratoryofNavigation,ControlandHealth‑ManagementTechnologiesofAdvancedAerocraft,MinistryofIndustryand

InformationTechnology,CollegeofAutomationEngineering,NanjingUniversityofAeronauticsandAstronautics,Nanjing

211106,

(Received15March2019;revised3April2019;accepted4April2019)

Abstract:Achievingaccuratenavigationinformationbyintegratingmultiplesensorsiskeytothesafeoperationof

landvehiclesinglobalnavigationsatellitesystem(GNSS)‑r,currentmulti‑sensor

fusionmethodsarebasedonstovepipearchitecture,whichisoptimizedwithcustomfusionstrategyforspecific

gtodevelopadaptablenavigationthatallowsrapidintegrationofanycombinationofsensorstoobtain

robustandhigh‑precisionnavigationsolutionsinGNSS‑deniedenvironment,weproposeagenericplug‑and‑play

posedstrategycanhandledifferentsensorsinaplug‑and‑play

mannerassensorsareabstractedandrepresentedbygenericmodels,whichallowsrapidreconfigurationwhenevera

veestimationsarefusedwithabsolutesensorsbasedon

improvedfactorgraph,whichincludessensors’errorparametersinthenon‑linearoptimizationprocesstoconduct

uatetheperformanceofourapproachusingalandvehicleequippedwithaglobal

positioningsystem(GPS)receiveraswellasinertialmeasurementunit(IMU),camera,wirelesssensorand

sarecomparedwiththemost

commonfiltering‑sthatourstrategycanprocesslow‑qualityinputsourcesina

plug‑and‑playandrobustmanneranditsperformanceoutperformsfiltering‑basedmethodinGNSS‑denied

environment.

Keywords:GNSS‑denied;multi‑sensorfusion;plug‑and‑play;factorgraph;landvehicles

CLCnumber:V249.32Documentcode:AArticleID:1005‑1120(2019)02‑0197‑08

0Introduction

Oneoftheessentialtechnologiesthatensurere‑

thefieldoflandvehicles

[2‑4]

.However,thesenaviga‑

tionsystemsarebasedonstovepipearchitecture

[5]

whichiscustomizedforspecificsensorsandmea‑

gsabouthugecostswhen‑

everthenavigationsystemrequireschangesorup‑

geexistingfusionarchitectures,De‑

fenseAdvancedResearchProjectsAgency(DAR‑

PA),USAlaunchedAllSourcePositioningand

Navigation(ASPN)projectin2010

[6]

.ASPNproj‑

ectaimstodevelopadaptablenavigationthatallows

rapidintegrationofanycombinationofsensorstoen‑

ablelowcost,andseamlessnavigationsolutionsfor

militaryusersonanyoperationalplatformandinany

rentlandvehiclesheavilyrelyonglobalnavigation

satellitesystem(GNSS).However,whenlandvehi‑

clesruninthedenseorevenGNSS‑deniedenviron‑

ment,GNSSsignaldegradesorevenfailstolocate

landvehicles.

[1]

WhenGNSSsignalisunavailable,accurate

navigationsolutionscanbeobtainedthroughinte‑

‑sensorfusionmeth‑

odshavebeendeeplystudiedandwidelyappliedin

*Correspondingauthor,E‑mailaddress:laijz@.

Howtocitethisarticle:LAIJizhou,BAIShiyu,XUXiaowei,icPlug‑and‑PlayNavigationFusionStrategy

forLandVehiclesinGNSS‑DeniedEnvironment[J].TransactionsofNanjingUniversityofAeronauticsandAstronautics,

2019,36(2):197‑204.

http:///10.16356/j.1005‑1120.2019.02.002

198

TransactionsofNanjingUniversityofAeronauticsandAstronauticsVol.36

searchershaveperformedre‑

searchonASPN.

Forthesoftwaresystems,ElsnerandJuangde‑

signedtheplug‑and‑playmultisensoryfusion

schemesbasedonrobotoperatingsystem

(ROS)

[7‑8]

.Forthefusionarchitecturesandalgo‑

rithms,filtering‑basedestimationmethodsaremost‑

edreconfigurableinte‑

grationfilteringEngine(RIFE).InRIFE,various

classisdefinedbythetypeofsensormeasurement

andthefiltercanbereconfiguredbyinstantiatinga

sensorobjectwheneveranewsensorisconnectedto

system

[9]

.edmulti‑sensor‑fusion

extendkalmanfilter(MSF‑EKF)toprocess

time‑delayed,relativeandabsolutemeasurements

fromatheoreticallyunlimitednumberofdifferent

ulardesignallowsseamlesshan‑

dlingofadditional/lostsensorsignals

[10]

.Groves

proposedsensorfusionmodularintegratedarchitec‑

ture,wheredifferentsubsystemsareconstructedto

processandintegratedifferentsources

[11]

.Zhuetal.

presentedagoal‑

time,power,andweightarecombinedtoreconfig‑

uresensorsuiteandallchosenmeasurementsarein‑

tegratedusingEKF

[12]

.Althoughaboveresearch

hasachievedsatisfactoryresults,thefiltering‑based

methodshaveincommonthattheyrestrictthestate

vectortothemostrecentstateandmarginalizeout

alloldinformation,whichbringsoutsuboptimalper‑

formance

[13‑14]

.Incontrasttofiltering‑basedmeth‑

ods,agraphicalmodelknownasfactorgraphrepre‑

sentsinformationfusionproblemasagraph‑based

desthe

connectivitybetweentheunknownvariablenodes

ensoryfusion

methodsviafactorgraphcanhandledelayedand

asynchronoussourcesinaflexiblewaybecausepast

statesarekeptduringtheglobaloptimizationpro‑

cess

[15]

.AnditoutperformsEKFbecauseofthe

re‑linearizationprocess

[16]

.eda

constrainedoptimalselectionforsensorsbasedon

factorgraphandtheoptimalsubsetsofsensorsare

selectedwithavailableresources,navigationaccura‑

cyandobservabilityindex

[17]

.Consideringthere‑

al‑timeapplication,edaslid‑

ing‑windowfactorgraphmethodforautonomousve‑

hicles

[18]

.tedtheeffectiveness

ofrobustoptimizationtechniquesusingthefactor

sthatthefactorgraphal‑

gorithminconjunctionwithrobustoptimizationcan

achievereasonableperformanceintheGNSS‑de‑

gradedenvironment

[19]

.However,aboveresearchis

stilloptimizedwithcustomfusionsolutions,which

isinadequatefortheflexibleandextensibleneedsof

landvehiclesnavigationsystem.

Seekingtodevelopadaptablenavigationthatal‑

lowsrapidintegrationofanycombinationofsensors

toenableseamless,robustandaccuratenavigation

solutionsinGNSS‑deniedenvironment,wepro‑

poseagenericplug‑and‑playfusionstrategybased

ategyisde‑

sabstract

sensormodelsaredesignedbythetypeofsensors,

ensoris

connectedintothenavigationsystem,thespecific

sensormodelisbuiltfromtheabstractmodelandits

posed

strategyallowsrapidreconfigurationofanycombina‑

,itsmodularityenablesthefu‑

sionarchitecturetobeflexibleandextensibletonew

tion,time‑de‑

layedsensordata,whichpresentslow‑qualitychar‑

acteristics,canbeprocessedinanaturalwaybased

ontheimprovedfactorgraph,inwhicherrorparam‑

etersofsensorsarealsoaddedintothegraphmodel

uate

performanceoftheproposedstrategyusingaland

showsthatourstrategycanprocesslow‑qualitydata

inaplug‑and‑playandrobustmanneranditsperfor‑

manceoutperformsthemostcommonfilter‑based

method.

1GenericSensorFusionStrategy

TheproposedstrategyisshowninFig.1,whi‑

chconsistsofthreeparts,preprocessinglayer,ab‑

stractinglayerandfusinglayer.

No.2LAIJizhou,icPlug‑and‑PlayNavigationFusionStrategyforLandVehicles…

199

Fig.1Genericmulti‑sensorfusionstrategy

1.1Preprocessinglayer

Inthepreprocessinglayer,rawmeasurement

sourcesareprocessedintousablenavigationinfor‑

ensorisconnectedintothesys‑

tem,itisrecognizedandcorrespondingIDisat‑

,dataconversionis

ample,imagesofcameraareconvertedintoposees‑

eringthatsensorsareplacedindif‑

ferentlocationsofavehicle,spatialparameters

amongdifferentsensorsobtainedfromanofflinecal‑

ibrationareoffsetinspace‑,

ve

andabsolutemeasurementsarealsoalignedbytrans‑

formationbetweendifferentframes.

1.2Abstractinglayer

Intheabstractinglayer,variousabstractsensor

modelsaredesignedaccordingtothetypeofsen‑

yerconsistsoffourabstractmodels,

thatis,deadreckoningmodel,positionmodel,ve‑

locitymodel,cificmod‑

elofasensorcanbeinstantiatedusingitstemplates

byidentifyinginformation’,sensorerror

mple,asensor’s

specificnoiseanderrorparametersareaddedinto

thebuiltmodel.

Deadreckoningmodelrepresentsrecursivesen‑

sors,suchasinertialorotherdeadreckoningsen‑

tractmodelcanbeconceptuallyde‑

scribedbyfollowingcontinuousnonlineardifferen‑

tialequation

x=f

DR

(

x,α,Δ

)

(1)

where

x

isthenavigationstate,representingtheve‑

hicle’sposition,attitudeandvelocity;

Δ

theincre‑

mentofthevehiclemeasuredbysensorsand

α

the

odels

representsensorsthatprovidewithothermeasure‑

mentinformation,thatis,position,velocityandat‑

bstractmodelscanbedescribedina

unifiedway

z=h

M

(

x

)

+n

(2)

where

x

isnavigationstate,representingthevehi‑

cle’sposition,attitudeandvelocity;

z

theinforma‑

tionmeasuredbysensorsand

n

ameasurement

noise,whichisassumedtobezeromeanGaussian

noise.

h

M

isthemeasurementfunction,relatingbe‑

tweenthemeasurementandnavigationstate.

1.3Fusinglayer

Inthefusinglayer,non‑linearoptimization

torgraphisabipartitegraph

G=

(

F,X,E

)

with

twotypesofnodes:Factornodes

f

i

∈F

andvari‑

ablenodes

x

i

∈X

.Edges

e

ij

∈E

canexistonlybe‑

tweenfactornodesandvariablenodes,andarepres‑

entifandonlyifthefactor

f

i

involvesavariable

x

i

.

Thefactorgraph

G

definesonefactorizationofthe

function

f

(

X

)

as

f

(

X

)

=f

i

(X

i

)

(3)

where

X

i

isthesetofallvariables

x

i

connectedby

anedgetofactor

f

i

20]

.

Afactordescribesanerrorbetweenthepredict‑

ngaGaussian

noisemodel,ameasurementfactorcanbewrittenas

f

i

(X

i

)=d[h

i

(X

i

)-z

i

]

(4)

where

h

i

(X

i

)

isthemeasurementmodelasafunc‑

tionofthestatevariables

X

i

z

i

theactualmeasure‑

mentand

d(⋅)

acostfunction,whichisthesquared

Mahalanobisdistance,definedas

d

(

e

)

≜e

T

Σ

-1

e

with

Σ

s

modelscanberepresentedusingfactorsinasimilar

manner.

Eq.(3)shouldbeminimizedbyadjustingthe

estimatesofthevariables

X

.Theoptimalestimateis

200

TransactionsofNanjingUniversityofAeronauticsandAstronauticsVol.36

theonethatminimizestheerroroftheentire

graph

[21]

X

=argmin

X

(

f

i

(X

i

i

))

(5)

Differentsensorinformationisaddedintothe

time‑delayedandasynchronousmeasurementscan

beincorporatedintothefactorgraphinanatural

way,leadingtobetterestimatesforcurrentstates.

2AnImprovedSensorFusion

MethodforLandVehiclesBased

onFactorGraph

Thestructureoftheimprovedmultisensoryfu‑

nfactorgra‑

phframework,sensorerrorsareaddedintothe

optimizederrorparametersareutilizedtocalibrate

osensorerroronline

calibration,betterestimatesforthewholetrajectory

canbeobtained.

Fig.2Structureoftheimprovedfusionmethod

Consideringthatthemostcommonsensorsin

typicalnavigationapplicationsoflandvehicles,im‑

provedfactorgraphforlandvehiclesisbuiltin

sideredsensorsareIMU,GPS,od‑

ometer,visualsensors,

thispaper,GPSfactorisbuiltinthegraphmodelto

r,GPS

signalisnotfusedwithothersensorsbutusedas

groundtruthinthefieldteststoprovetheperfor‑

manceoftheproposedalgorithminGNSS‑denied

environment.

Sensors’errorparametersareaddedintograph

Fig.3Improvedfactorgraphforlandvehicles

ollowcir‑

clesmeannavigationstatesand

f

IMU

meansIMU

hollowcirclesmeanIMUbias,which

isintroducedatalowerfrequencythannavigation

solidcirclesmeanodometerfactorwhilegreyhol‑

lowcirclesrepresentscalefactorerrorofodometer.

Red,yellowandpurplesolidcirclesmeanvisual

odometry,wirelesssensor,andGPSfactor,respec‑

ollowcirclesrepresentscaleerrorof

tionstatesoflandvehiclesanderror

parametersofsensorsareoptimizedtogethertoim‑

arametersare

sorfactorsarebuiltasfollows

2.1IMUfactor

IMUfactorisbuilttoconnectnavigationstates

eringtime

k

andtime

k+1

,IMUfactorisderivedas

f

IMU

(x

k+1

,x

k

k

)≜d(x

k+1

-h(x

k

k

,z

k

))

(6)

where

x

k+1

and

x

k

arenavigationstatesattime

k+1

and

k

,respectively;

z

k

=

[

α

k

ω

k

]

isthegiv‑

enIMUmeasurements,thatis,accelerationandan‑

gularrate;

α

k

thebiasofinertialsensor,whichises‑

er

integrationpredictionfunctionwithanoiseisadopt‑

edtorepresent

h(⋅)

.Inthesameway,biasfactor

canbedescribedas

f

bias

k+1

k

)≜d(α

k+1

-g(α

k

))

(7)

where

α

k+1

and

α

k

arethebiasesattime

k+1

and

k

,modelledasconstanterror.

2.2Odometerfactor

Odometerprovideswithvelocityinformation

anditsfactorcanberepresentedas

f

ODO

(x

k

k

)≜d(z

ODO

k

-h

ODO

(x

k

k

))

(8)

No.2LAIJizhou,icPlug‑and‑PlayNavigationFusionStrategyforLandVehicles…

201

where

z

ODO

k

and

x

k

arethevelocitiesofodometerand

navigationstateattime

k

β

k

isthescalefactorer‑

ror,

thesameway,scalefactorerrorcanbederivedas

f

scale

k+1

k

)≜d(β

k+1

-g(β

k

))

(9)

where

β

k+1

and

β

k

arethescalefactorerrorsattime

k+1

and

k

,actorerrorismod‑

elledasconstanterror.

2.3GPSfactor

GPSfactorisbuilttoprovidewithabsolutepo‑

sitionanditsfactorcanbemodelledas

f

GPS

(x

k

)≜d(z

GPS

k

-h

GPS

(x

k

))

(10)

where

z

GPS

k

and

x

k

arethepositionsofGPSandnavi‑

gationstateattime

k

.

2.4Wirelesssensorfactor

Wirelesssensorprovidesranginginformation

relesssensorcanreceive

atleastthreeranginginformationtobasestations

whosepositionsareobtainedinadvance,itcanpro‑

videwithpositioninthegivenframesanditsfactor

canbemodelledas

f

WS

(x

k

)≜d(z

WS

k

-h

WS

(x

k

))

(11)

where

z

WS

k

and

x

k

arethepositionsofwirelesssensor

andnavigationstateattime

k

.

2.5Visualsensorfactor

Visualsensorprovideswithrelativeposition

he

relativeandabsolutemeasurementsarealigned,it

provideswithposeinformationintheglobalframe.

Itsfactorcanberepresentedas

f

VOP

(x

k

)≜d(z

VOP

k

-h

VOP

(x

k

k

))

(12)

f

VOH

(x

k

)≜d(z

VOH

k

-h

VOH

(x

k

))

(13)

where

z

VOP

k

and

x

k

arethepositionofvisualsensor

andnavigationstateattime

k

z

VOH

k

istheyawofvi‑

sualsensorattime

k

λ

k

thescaleerroranditismod‑

torcanberepresented

as

f

scale

k+1

k

)≜d(λ

k+1

-g(λ

k

))

(14)

where

λ

k+1

and

λ

k

arethescaleerrorsattime

k+1

and

k

,respectively.

3Experiment

Inthefieldtests,weusealandvehicle

equippedwithaGPSreceiveraswellasIMU,ste‑

reocamera,UWB(akindofwirelesssensor)and

receiverprovideswithprecisepositioningofcenti‑

meter‑levelsolutionswhenitoperatesinreal‑time

kinematic(RTK)mode,whichistreatedasground

otintegratedintothenavigationsys‑

tem,whichonlytoevaluatetheperformanceofthe

proposedstrategyinGNSS‑deniedenvironment.

DataacquisitionmoduleisdesignedbasedonROS.

Fig.4Landvehicleusedinthefieldtest

Thetrajectoryofthefieldtestisshownin

rtingpointismar‑

kedwithastarandarrowsshowthedrivingdirec‑

incolorofthetrajectorymeansthecor‑

respondingsectionwhereacertaincombinationof

sensorsisintegratedintothenavigationsystem,be‑

causesomesensorsareavailableinspecificcircum‑

mple,redlineissurroundedby

basestations,andtheUWBisavailableonlyinthis

,theroadwayinbluepartisthearea

wherefeatureissparse,whichleavesthecamerain

anunusablestateandnotbeintegratedintothenavi‑

est,differentinformation

sourcesareintegratedtothesystemwheneverthey

areavailable.

Whenasensorisconnectedintosystem,spe‑

cificmodelsareconstructedandcorrespondingfac‑

e‑de‑

layedandasynchronousmeasurementscanbefused

inthefactorgraphinatrulyplug‑and‑playmanner

sincepaststatesarekepttoperformglobaloptimiza‑

tion.

Wecompareourresultswiththemostcommon

filtering‑basedmethod,wbackofa

202

TransactionsofNanjingUniversityofAeronauticsandAstronauticsVol.36

Fig.5FieldtestingeneralroadcampusofNUAA

basicEKFisthatlinearizationhappensonlyonce,

,EKF

issensitivetotime‑delayedmeasurementswhich

presentslow‑qualitycharacteristics,asstatescannot

uateimpacts

oflow‑qualityinformationonEKF,weaddtimede‑

laysandnoiseintosensordataatdifferenttimes,

delayissettobe1s,whichislargeenoughtoim‑

plementerrorexcitation.

ThetrajectorycomparisonisshowninFig.6.

Theeastandthenorthpositionerrorcomparisons

areplottedinFigs.7,8,inwhichthetimeperiods

withfaultedVOmeasurementsaremarkedwith

eethatbothfusionmethods

presentslowdriftasthereisnoabsoluteposition

,positionerrorsof

EKFarehighlyincreasedduringperiodswhenfault‑

ontrary,sincepaststates

arekeptinglobaloptimizationprocess,delayedin‑

formationcanbeaddedtographmodelbasedon

theirtimestampinaplug‑and‑playway,leadingto

‑mean‑square

Fig.6Trajectorycomparison

Fig.7Eastpositionerrorcomparison

Fig.8Northpositionerrorcomparison

(RMS)errorsofthepositionerrorisillustratedin

Table1.

Table1RMScomparisonm

RMSEastNorth

EKF10.7813.80

Proposedmethod5.999.44

4Conclusions

Weproposeagenericplug‑and‑playmulti‑sen‑

sorsfusionstrategyforlandvehiclesinGNSS‑de‑

ategyhandlesdifferent

sensorsinaflexiblewayassensorsarerepresented

veestimationsare

fusedwithabsolutesensorsbasedonimprovedfac‑

torgraph,inwhichsensors’errorparametercanbe

addedintographoptimizationtoperformsensoron‑

nstratetheperformanceof

sthattradi‑

tionalfilteringmethodisheavilyinfluencedby

low‑ategycanprocess

time‑delayedinputsourcesinaplug‑and‑playandro‑

bustmanneranditsperformanceoutperformsEKF

inGNSS‑deniedenvironment.

Inourfuturework,theintegratedqualityof

themeasurements,notjustrestrictedtosensoraccu‑

No.2LAIJizhou,icPlug‑and‑PlayNavigationFusionStrategyforLandVehicles…

203

racy,willbeconsideredtomeasuresensor’sconfi‑

dencelevelinthefusionprocess,thusfurtherim‑

provingrobustnessandaccuracyofthesystem.

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Acknowledgements

Thisworkwaspartiallysupported

bytheNationalNaturalScienceFoundationofChina(No.

61703207),theJiangsuProvincialNaturalScienceFounda‑

tionofChina(20170801),theAeronauticalScience

FoundationofChina(No.2017ZC52017),andtheJiangsu

ProvincialSixTalentPeaks(No.2015‑XXRJ‑005),andthe

JiangsuProvinceQingLanProject.

innavi‑

gation,guidanceandcontrolfromNanjingUniversityof

AeronauticsandAstronautics,Nanjing,China,

iscurrentlyafullprofessoratAutomationEngineeringCol‑

lege,earchhasfocusedoninertialand

GNSSnavigation,multi‑sensorfusionandfault‑tolerantnav‑

igation,autonomousnavigationinGNSS‑deniedenviron‑

ment,visualnavigation,deeplearningandsensing,andcol‑

laborativenavigation.

ateatNanjing

earchis

focusedonmulti‑sensorfusion.

ateinNanjing

earchis

focusedondownholeautonomousnavigation.

Dr.LÜinnavigation,guid‑

anceandcontrolfromNanjingUniversityofAeronauticsand

Astronautics,Nanjing,China,rrentlyalec‑

turerinNanjingUniversityofAeronauticsandAstronautics.

Hisresearchisfocusedonrotationalinertialnavigationand

dynamicmodelassistednavigation.

houdesignedthestudy

yuconductedthe

weipartici‑

.LÜPincontributedtothedis‑

horscommented

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