GNSS-aided INS for land vehicle positioning and navigation

136 Pages·2007·3.71 MB·English

ThesisforthedegreeofLicentiateofEngineering
GNSS-aided INS for land vehicle positioning and
navigation
IsaacSkog
SignalProcessing
SchoolofElectricalEngineering
KTH(RoyalInstituteofTechnology)
Stockholm2007
Skog,Isaac
GNSS-aidedINSforlandvehiclepositioningandnavigation
Copyright(cid:13)c2007IsaacSkogexceptwhere
otherwisestated.Allrightsreserved.
TRITA-EE2007:066
ISSN1653-5146
SignalProcessing
SchoolofEletricalEngineering
KTH(RoyalInstituteofTechnology)
SE-10044Stockholm,Sweden
Telephone[phone]
Abstract
This thesis begins with a survey of current state-of-the art in-car navigation sys-
tems. The pros and cons of the four commonly used information sources (cid:150)
GNSS/RF-basedpositioning,vehiclemotionsensors,vehiclemodelsandmapin-
formation (cid:150) are described. Common (cid:2)lters to combine the information from the
varioussourcesarediscussed.
Next,aGNSS-aidedinertialnavigationplatformispresented,intowhichfur-
thersensorssuchasacameraandwheel-speedencodercanbeincorporated. The
constructionofthehardwareplatform,togetherwithanextendedKalman(cid:2)lterfor
a closed-loop integration between the GNSS receiver and the inertial navigation
system(INS),isdescribed. Resultsfroma(cid:2)eldtestarepresented.
Thereafter,anapproachisstudiedforcalibratingalow-costinertialmeasure-
mentunit(IMU),requiringnomechanicalplatformfortheaccelerometercalibra-
tionandonlyasimplerotatingtableforthegyrocalibration. Theperformanceof
thecalibrationalgorithmiscomparedwiththeCramr-Raoboundforcaseswhere
amechanicalplatformisusedtorotatetheIMUintodifferentpreciselycontrolled
orientations.
Finally, the effects of time synchronization errors in a GNSS-aided INS are
studiedintermsoftheincreasederrorcovarianceofthestatevector. Expressions
forevaluatingtheerrorcovarianceofthenavigationstatevectorarederived. Two
differentcasesarestudiedinsomedetail.The(cid:2)rstconsidersanavigationsystemin
whichthetimingerrorisnottakenintoaccountbytheintegration(cid:2)lter. Thisleads
toasystemwithanincreasederrorcovarianceandabiasintheestimatedforward
acceleration. Inthesecondcase,aparameterizationofthetimingerrorisincluded
as part of the estimation problem in the data integration. The estimated timing
errorisfedbacktocontrolanadjustablefractionaldelay(cid:2)lter,synchronizingthe
IMUandGNSS-receiverdata.
i

Acknowledgements
Firstofall,Iwouldliketoexpressmydeepestgratitudetomyadvisor,Professor
Peter Ha¤ndel, for his ideas, inspiration and enormous support. I look forward to
workingwithyouforanothercoupleofyears!
Iwouldliketothankmycolleaguesat(cid:148)plan4(cid:148)formakingworkapleasure.To
myfriends,whohaverepeatedlyaskedmewhataPhDstudentactuallydoesand
whatIamworkingonand,thoughtheymaynothavefullyunderstoodmyanswers,
still support me. Put simple, the work of a PhD student can be summarized as
follows: Choose a topic (in my case land vehicle navigation), read one hundred
papers on it, write a new paper with a couple of amendments so that the next
personinlinewillhavetoreadonehundredandonepapers,presentyourresultsat
aconferenceinacarefullychosenlocationand, lastly, iteratetheprocessseveral
times. Thanksforbringingalotofjoyandfunintomylife.
Finally, and most importantly, I would like to thank my mother, Margareta,
andmyfather,Rolf,forlettingmeasachildbringhomeandtakeapartalltheold
televisionsandstereosIcould(cid:2)nd-that’showitallstarted. Ioweitalltoyou. To
mybrother,Elias,andmyhalf-sister,Julia,Iloveyouthemost!
iii

Contents
Abstract i
Acknowledgements iii
Contents v
I Introduction 1
Introduction 1
1 ContributionsoftheThesis . . . . . . . . . . . . . . . . . . . . . 1
2 Relatedpapersnotincludedinthethesis . . . . . . . . . . . . . . 4
II Includedpapers 5
A State-of-theartandfuturein-carnavigationsystems(cid:150)asurvey A1
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A1
2 State-of-theartsystems . . . . . . . . . . . . . . . . . . . . . . . A3
3 GlobalNavigationSatelliteSystemsandAugmentSystems . . . . A5
4 VehicleMotionSensors . . . . . . . . . . . . . . . . . . . . . . . A8
4.1 Deadreckoningandinertialnavigation . . . . . . . . . . A13
5 Vehiclemodelsandmotions . . . . . . . . . . . . . . . . . . . . A16
6 Mapinformation . . . . . . . . . . . . . . . . . . . . . . . . . . A18
7 InformationFusion . . . . . . . . . . . . . . . . . . . . . . . . . A20
7.1 Non-linear(cid:2)ltering . . . . . . . . . . . . . . . . . . . . . A21
8 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A22
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A23
B A low-cost GPS aided inertial navigation system for vehicle applica-
tions B1
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B1
2 NavigationDynamics . . . . . . . . . . . . . . . . . . . . . . . . B2
v
2.1 Navigationequations . . . . . . . . . . . . . . . . . . . . B2
2.2 Errorequations . . . . . . . . . . . . . . . . . . . . . . . B3
3 Discretization . . . . . . . . . . . . . . . . . . . . . . . . . . . . B5
3.1 Discretetimenavigationequations . . . . . . . . . . . . . B5
3.2 Discretetimeerrorequations . . . . . . . . . . . . . . . . B5
4 ExtendedKalmanFiltering . . . . . . . . . . . . . . . . . . . . . B6
5 DesignandConclusions . . . . . . . . . . . . . . . . . . . . . . B8
5.1 HardwareDesign . . . . . . . . . . . . . . . . . . . . . . B9
5.2 Simulationresults . . . . . . . . . . . . . . . . . . . . . B9
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B11
C AVersatilePC-BasedPlatformForInertialNavigation C1
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C1
2 SystemOverview . . . . . . . . . . . . . . . . . . . . . . . . . . C2
3 Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C2
4 SoftwareAlgorithm . . . . . . . . . . . . . . . . . . . . . . . . . C4
5 Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C8
6 ConclusionsanFurtherWork . . . . . . . . . . . . . . . . . . . . C9
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C11
D CalibrationofaMEMSinertialmeasurementunit D1
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D1
2 SensorErrorModel . . . . . . . . . . . . . . . . . . . . . . . . . D2
3 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D6
4 Crame·rRaoLowerBound . . . . . . . . . . . . . . . . . . . . . D8
5 Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D9
5.1 PerformanceEvaluation . . . . . . . . . . . . . . . . . . D9
5.2 CalibrationofIMU . . . . . . . . . . . . . . . . . . . . . D10
6 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D11
AppendixA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D15
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D15
E TimesynchronizationerrorsinGPS-aidedinertialnavigationsystems E1
1 Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . E1
2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E3
3 Covarianceoftheestimationerror . . . . . . . . . . . . . . . . . E4
3.1 Closed-LoopError . . . . . . . . . . . . . . . . . . . . . E6
3.2 TimingErrorsinClosed-Loop . . . . . . . . . . . . . . . E7
3.3 Example: Single-axisGPS-aidedINS . . . . . . . . . . . E9
4 Modellingthetimingerrorintheintegration(cid:2)lter . . . . . . . . . E13
4.1 Example: Single-axisGPS-aidedINS,revisited . . . . . . E17
5 Implementingavariabledelayinthenavigation(cid:2)lter . . . . . . . E17
6 Timesynchronizationappliedtoalow-costGPS-aidedINS . . . . E20
6.1 Simulateddata . . . . . . . . . . . . . . . . . . . . . . . E21
vi
6.2 Real-worlddata . . . . . . . . . . . . . . . . . . . . . . . E23
7 Observabilityoftimedelayerror . . . . . . . . . . . . . . . . . . E34
8 ResultsandConclusions . . . . . . . . . . . . . . . . . . . . . . E35
AppendixA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E36
AppendixB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E38
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E39
vii