muhammad waqas ahmad khan statistical sensor fusion of ultra wide band ranging and real time ...

55 Pages·2014·4.52 MB·English

MUHAMMAD WAQAS AHMAD KHAN
STATISTICAL SENSOR FUSION OF ULTRA WIDE BAND RANGING
AND REAL TIME KINEMATIC SATELLITE NAVIGATION
Master’s Thesis
Examiners: Professor Robert Piche,
Associate Professor Elena-Simona
Lohan
Examiners and topic approved by the
Faculty Council of the Faculty of
Computing and Electrical
Engineering on 4th June, 2014.
II
ABSTRACT
TAMPERE UNIVERSITY OF TECHNOLOGY
Master’s Degree Program in Electrical Engineering
KHAN, MUHAMMAD WAQAS AHMAD: Statistical Sensor Fusion of Ultra Wide
Band Ranging and Real Time Kinematic Satellite Navigation.
Master of Science Thesis, 46 pages, 00 Appendix page
November 2014
Major subject: RF Electronics
Examiners: Professor Robert Piche and Associate Professor Elena-Simona
Lohan.
Keywords:Real Time Kinematic (RTK), Global Positioning System (GPS),
Ultra-Wide Band (UWB), Kalman Filter (KF), Cycle Slip (CS), Integer Ambiguity
(IA), Base Station (BS), Rover, Fusion.
Position,velocityandtime(PVT)canbecalculatedfromGlobalPositioningSystem(GPS).
TwotypesofGPSmeasurementmodelsarepresent,codephasemeasurementmodeland
carrier phase measurement model. Range measurement in GPS is affected by different
typesoferrorsincludingatmospheric,multipath,satelliteandreceiverclockandephemeris
errors. Atmosphericerrorsarethebiggestsourceoferroramongstthese.
Receiverswithincloseproximitytoeachotherfacemostlysameatmosphericerrors
from GPS signal. Several differential techniques have been developed during the last
few years to mitigate these common errors. It means that the accuracy can be improved
byusingmultiplereceiverswhichmitigatethemajorityoferrors. RealTimeKinematic
(RTK) concept uses carrierphase measurements, which havehigh accuracy. RTK concept
was originally developed for application such as surveying. The unknown ambiguity in
the number of cycle between each satellite and receiver node is the main issue in RTK
technique,moreoverthese ambiguitiesareinteger numbers. Oncetheambiguity issolved,
it remains constant as long as the receiver maintains a phase lock on satellites signals.
However,thelossofphaselockresultsincycleslipsandtheambiguityneedstosolveagain.
Inthiswork,RTKLIB,anopensourcesoftware,isusedfortheRTKGPSpositioning.
Ultra-Wide Band (UWB) is known since early 1900s with synonymous terms such
asimpulse,timedomain,nonsinusoidal,baseband,carrierfree,orthogonalfunctionand
largerelativebandwidthradiosignals. ThehugefrequencybandwidthofUWBmakesit
suitableforpositioningandnavigationapplications. Multipathresistance,highaccuracy,
lowcostand lowpowerimplementationare otherfeaturesof UWB.Thehugebandwidth
infrequencydomaincorrespondstoshortpulseintimedomain,usuallyofnanosecond(ns)
order. The Time ofarrival (TOA),the timedifference of arrival(TDOA) andthe received
signalstrength(RSS)areknownmethodstocalculatetherangebetweenthesourceandthe
target through UWB. TOA and TDOA are highly accurate but have clock synchronization
problem. Toovercomethisproblem,amodifiedmethodknownastwo-waytime-of-flight
canbeused. BeSpoonphoneequippedwithUWBisusedhereforUWBranging.
To summarize the previous discussion, RTK GPS positioning has a high accuracy
but has integer ambiguity resolution problemwhich causes cycle slips and requires good
satellitevisibilityaswell. MoreoverRTKGPSpositioningsolutionisforoutdoorapplica-
tionsonlyandhashighdynamicoutdoorrange. UWB,ontheotherhand,cangivehighly
accurate positioning solution but has low dynamic range. UWB can be used for both
indoorandoutdoorapplications. Moreover,highbandwidthofUWBmakesitmultipath
resistant and as result can be used in shadow areas. Thus, the fusion of RTK GPS and
III
UWBpositioningmaycompensatesthelimitationsofbothandresultinbetterperformance
system. InthisthesisaKalmanfilterisusedforfusionofUWBandRTKGPSpositioning
solutions.
UWBgives range fromtagswhichareinmeter andrelativetoBeSpoonphone while
RTK GPS positioning solution is in geodetic coordinates form (latitude and longitude).
Threestepsareinvolvedinfusion;first,convertUWBrangestopositioninlocalcoordinate
byusing trilateration, second, convert geodeticcoordinatesofRTK GPStolocal coordi-
nates through rotation matrix and third, use Kalman filter for fusion of both positioning
data. The main goal of the thesis is the fusion of both RTK GPS and UWB positioning
solutionswiththehelpofKalmanfilterinordertoobtainbetterperformancecompareto
stand-aloneRTKGPS.
Tampere University of Technology (TUT)parking areais used fortesting. Onecorner
ofTUTparkingareahastheknowncoordinatepointwhichisusedforthebasestationof
RTKGPS.ReferencetrackandtagspositionsaredrawnthroughLaserinstrumentLeica
TPS1200whichhasmillimeterlevelofaccuracy.
MeasurementresultsshowthatthefusionofUWBandRTKGPSpositioningsolutions
havebetter performance compared to stand-aloneRTKGPS solution. Whenever measure-
mentfromRTKGPSgiveserroneous/missingresult,themeasurementfromUWBsensor
correctsitandtheresultingsolutionfromfilterhasbetterperformance.
IV
PREFACE
This Master of Science thesisis writtenin collaborationof Departmentof Electronicsand
CommunicationsEngineeringandDepartmentofAutomationScienceandEngineering.
ThisthesisisfundedbyDepartmentofAutomationScienceandEngineering. TheworkI
havedoneasresearchassistantispresentedinthisthesis.
Ithank my supervisorsProfessorRobertPiche andAssociateProfessorElena-Simona
Lohanfor their continuoussupport,guidance andvaluablefeedback. Ialsothank Hannu
KupilaandJoonas Melinforproviding necessary equipment. Iwould liketomentionmy
research group membersspecially Simo Ali-Löytty, Helena Leppäkoski, Pavel Davidson,
HenriNurminen,DavideLaCroce,JuhaAla-Luhtala,VilleHuttunenandPhilippMuller
fortheirhelp.
I want to thank all my friends specially Shahbaz, Rao Uzair, Safdar, Rizwan and
Hareshfor theirhelpduring mymeasurements. Iwouldlike tothank myfamilyfor their
continuoussupporttomakethisthesispossible.
TampereNovember10,2014
MuhammadWaqasAhmadKhan
Tampere,Finland.
V
TABLE OF CONTENTS
1.Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1. Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2. Thesismotivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3. Researchobjective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.4. Authorcontributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.5. Thesisoutline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.Theoreticalbackground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Ultra-WideBand(UWB) . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1.1. UWBhistory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1.2. UWBsignaldefinition . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1.3. UWBranging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1.4. TestingandresultsofBeSpoonphoneUWB . . . . . . . . . . . . . . 12
2.2. RealTimeKinematic(RTK)GPS . . . . . . . . . . . . . . . . . . . . . . 13
2.2.1. RTKGPSbackground . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.2.2. RTKLIB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.2.3. RTKGPSconfiguration . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.2.4. Testingandresult . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.3. TheKalmanfilterfordatafusion . . . . . . . . . . . . . . . . . . . . . . . 22
2.4. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.UWBandRTKGPSfusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.1. UWBandRTKGPSfusionconfiguration . . . . . . . . . . . . . . . . . . 26
3.2. Kalmanfilterfusionparameters . . . . . . . . . . . . . . . . . . . . . . . 30
3.3. Testingmethod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
3.4. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.Resultsanddiscussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4.1. Resultwith6UWBtags . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4.2. Resultwith4UWBtags . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
4.3. Comparisonofresults . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
4.4. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
5.Conclusionsandfuturework . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
5.1. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
5.2. Futurework . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
VI
LIST OF FIGURES
2.1 UWBsignaldefinition. . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 UWBexamplepulseshape. . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.3 4bits1010transmissionthroughUWBsignal. . . . . . . . . . . . . . . . 7
2.4 ECCEIRPemissionlimitsforUWBsystemwithoutappropriatemitigation
techniques[1]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.5 ECCEIRP emissionlimitsfor UWBsystemwith appropriatemitigation
techniques[1]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.6 Rangingthroughtwo-waytime-of-flightmethod. . . . . . . . . . . . . . 10
2.7 BeSpoonphoneandsixtagsequippedwithUWB. . . . . . . . . . . . . . 12
2.8 Static line-of-sight error measurement (red *), linear regression line (con-
tinuousblueline)and95%credibilityintervallimits(greendashedline). . 13
2.9 Dynamic line-of-sight error measurement (red *), linear regression line
(continuousblueline)and95%credibilityintervallimits(greendashedline). 14
2.10 (a)Yuan10USBreceiver(b)ANN-MSu-bloxactiveGPSantenna . . . . 17
2.11 RTKLIBGUIAPsonwindows7OS. . . . . . . . . . . . . . . . . . . . 17
2.12 RTKNAVImainwindow. . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.13 RTKNAVIdataflow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.14 RTKGPSconfigurationthroughserialconnection. . . . . . . . . . . . . 20
2.15 RTKGPSconfigurationthroughWiFi. . . . . . . . . . . . . . . . . . . . 21
2.16 RTKGPSconfigurationthroughinternet. . . . . . . . . . . . . . . . . . 21
2.17 RTKGPSconfigurationthroughNTRIPCaster. . . . . . . . . . . . . . . 21
2.18 RTKGPSconfigurationusedinthesis. . . . . . . . . . . . . . . . . . . . 22
2.19 SampletestingresultofRTKGPSpositioning. . . . . . . . . . . . . . . 23
2.20 Kalmanfilterrecursivesteps. . . . . . . . . . . . . . . . . . . . . . . . . 23
3.1 UWBandRTKGPSfusionproperties. . . . . . . . . . . . . . . . . . . . 27
3.2 UWBandRTKGPSfusionconfigurationinourmeasurements. . . . . . 28
3.3 SampleUWBdataofapproximately1secfromBeSpoonphone. . . . . . 28
3.4 RTKGPS+UWBfusionprocessflow. . . . . . . . . . . . . . . . . . . . 29
3.5 Fusionfilteralgorithm. . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.6 Photoofaknowncoordinatepoint. . . . . . . . . . . . . . . . . . . . . . 32
3.7 GoogleEarth viewof testingsetup. Parkingis approximately100m long
and30mwide. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3.8 Frontviewoftestingsetup. . . . . . . . . . . . . . . . . . . . . . . . . . 34
3.9 Cart. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
3.10 Basestation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.1 ResultwithsixUWBtags. . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.2 Trackisdividedintothreesubtracks. . . . . . . . . . . . . . . . . . . . 37
VII
4.3 Resultwithcycleslip(simulated). . . . . . . . . . . . . . . . . . . . . . 39
4.4 ResultwithfourUWBtagssecondscenario. . . . . . . . . . . . . . . . . 39
4.5 ResultwithfourUWBtagsthirdscenario. . . . . . . . . . . . . . . . . . 40
5.1 Proposedhexacopternavigationsystemconfigurationforfuturestudies. . 43
VIII
LIST OF TABLES
2.1 Rangingerrorcalculationwithdifferentoscillatorerrors. . . . . . . . . . 10
2.2 ComparisonbetweenBeSpoonPhoneandZebraTechnologiesDartRTLS
UWB. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.3 Measurementerrorsforsinglefrequency(L1)receiver[2]. . . . . . . . . 15
2.4 RTKLIBfunctionsandGUIAPs[3]. . . . . . . . . . . . . . . . . . . . . 18
2.5 DiscreteKalmanfilterequationssummary. . . . . . . . . . . . . . . . . . 25
3.1 Coordinatedetailofsurveyedpoint. . . . . . . . . . . . . . . . . . . . . 32
4.1 RMSerror(m)comparisonofRTKGPS,UWBandfusionofUWBand
RTKGPSresults. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
4.2 RMSerror(m)comparisonoffusionresultswithandwithoutcycleslipof
subtrack2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
4.3 RMSerror(m)comparisonofRTKGPS,UWBandfusionofUWBand
RTKGPSresultswith4tags . . . . . . . . . . . . . . . . . . . . . . . . 38
4.4 RMSerror(m)comparisonofRTKGPS,UWBandfusionofUWBand
RTKGPSresultswith4and6tags . . . . . . . . . . . . . . . . . . . . . 41
IX
LIST OF SYMBOLS AND ABBREVIATIONS
GPS GlobalPositioningSystem
PRN Pseudo-RandomNoise
RTK RealTimeKinematic
UWB Ultra-WideBand
TOA TimeOfArrival
TDOA TimeDifferenceOfArrival
RSS ReceivedSignalStrength
KF KalmanFilter
BS BaseStation
WAAS WideAreaAugmentationSystem
INS InertialNavigationSystem
CS CycleSlip
FCC FederalCommunicationsCommission
SNR Signal-to-NoiseRatio
TH TimeHopping
IF IntermediateFrequency
EIRP EffectiveIsotropicRadiatedPower
ppm Parts-Per-Million
RHCP RightHandCircularPolarization
GUI GraphicalUserInterface
AP ApplicationProgram
PC PersonnalComputer
APK AndroidApplicationPackage
x StateVector
x EstimatedStateVector
(cid:98)
x (−) PriorivalueofStateVectoratepochk
k
x (+) PosteriorivalueofStateVectoratepochk
k
F DynamicMatrix
Q NoiseCovarianceMatrixorSystemNoiseMatrix
w DynamicNoiseMatrix
H ObservationMatrix
v MeasurementNoiseMatrix
R NoiseCovarianceMatrixorMeasurementNoiseMatrix
P (−) ErrorCovarianceMatrixatepochk
k
K KalmanGainMatrix
P (+) UpdatedErrorCovarianceMatrixatepochk
k
z InputMeasurementMatrix
σ StandardDeviation
1
1. INTRODUCTION
1.1. Background
In1960sGlobalPositioningSystem(GPS)wasestablishedandpresentlyitisfullyfunc-
tionaltocalculateposition,velocityandtime. Thesatelliteconstellationnormallyconsists
ofenoughNAVSTARsatellitesorbitinginsixdifferentorbitalplanessuchthatatleast4
satellitesare visible fromanywhereonthe Earth. Eachsatellite transmitssignalon several
L band frequencies. Two of them are L1 and L2 signals. L1 signal center frequency is
1575.42 MHz, while L2 signal center frequency is 1227.60 MHz. Moreover, in March
2009,anL5signalwasincludedwiththecenterfrequency1176.45MHz. GPScanserve
unlimited number of users because the receivers act as passive element. Moreover GPS
usesone-waytime-of-arrival(TOA)methodforranging. [2],[4]
GPSisaffectedbydifferenttypesoferrorsincludingatmospheric,satelliteandreceiver
clocks,multipathandephemeriserrors. Sincelastfewyears,severaldifferentialtechniques
havebeendevelopedtomitigatethecommonerrorsbetweentwoGPSreceiverscloseto
eachother. TherearethreebasictypesofaugmentationstoGPS.Thefirsttyperequiresthat
aninformationrelatedtotheadditionalerroristransmitted. TheSecondtypeisbasedon
thetransmissionofrawinformation. Thethirdtyperequirestheadditionaltransmissionof
othernavigationalinformationfromothersystems/sensors,suchasvelocity,acceleration,
etc.
The Wide Area Augmentation System (WAAS) developed by Federal Aviation Ad-
ministration (FAA), the European Geostationary Navigation Overlay System (EGNOS)
developedbyEuropeanSpaceAgency,the EuropeanCommissionandEUROCONTROL,
the Multifunction Satellite Augmentation System (MSAS) developed by Japanese and
theGPSAidedGEOAugmentedNavigation(GAGAN)developedbyIndiangovernment
are few systems that transmit correction to users for removing errors. Real Time Kine-
matic(RTK)techniquetransmitsrawdatafrombasestationtotheuser(rover)toremove
errors. SystemsincludingCompass(headingaiding),InertialNavigationSystem(INS),
high-stabilityclocks,terrainmapping/corrections,startrackingandVHFOmni-directional
Ranging(VOR)transmitdifferenttypesofinformationusedtoremoveerrors. [5]
GPS uses two types of measurement models: the code phase measurements and the
carrierphasemeasurements. Thecarrierphasemeasurementsgivegoodaccuracycompared
to code phase measurements but suffer from the cycle slips (CS) problem, because of
multipathandsatellitevisibilityissues. TheRealTimeKinematic(RTK)GPSusescarrier
phasemeasurementsandgivescentimeterlevelofaccuracy. Inordertomaintaincentimeter