Indoor Localization using Accidental Infrastructure

83 Pages·2013·6.66 MB·English

Delft University of Technology
Master’s Thesis in Embedded Systems
Indoor Localization
using Accidental Infrastructure
Zsolt Kocsi-Horva´th

Indoor Localization
using Accidental Infrastructure
Master’s Thesis in Embedded Systems
EmbeddedSoftwareSection
FacultyofElectricalEngineering,MathematicsandComputerScience
DelftUniversityofTechnology
Mekelweg4,2628CDDelft,TheNetherlands
ZsoltKocsi-Horva´th
[email protected]
4thJanuary2013
Author
ZsoltKocsi-Horva´th([email protected])
Title
IndoorLocalizationusingAccidentalInfrastructure
MScpresentation
15. January2013
GraduationCommittee
prof. dr. K.G.Langendoen(chair) DelftUniversityofTechnology
dr. ir. A.Phillips ARMR&D,Cambridge
ir. H.Vincent ARMR&D,Cambridge
dr. S.O.Dulman DelftUniversityofTechnology
dr. A.Iosup DelftUniversityofTechnology
Abstract
The level of the technological development of embedded devices is at a constant
rise. Wecanforeseeanear-futurescenariowhereahugenumberofsemi-intelligent
devicesarepartofoureverydayenvironment,ourhomes,thepublicplacesandthe
officeaswell. Theintelligentthermostatuploadsthetemperaturereadingstoanon-
linedatabase;thefridgesendsatweetwhenweareoutofmilk;thecoffeemachine
textsuswhenthecoffeeisready. Eachdevicehasauniqueandindividualpurpose.
Butwhatiftheycouldbegroupedtogetherasaso-calledaccidentalinfrastructure
toserveamoreadvancedcause?
Wehavesetouttodemonstratethepossibilitiesofsuchanaccidentalinfrastructure
in the field of indoor localization. An ambient device in itself is not intentionally
preparedforlocalizationpurposes,butusingmanyofthemtogetherandcombining
thecollecteddatacansurpassthedevices’limitedindividualcapabilities.
Our approach was to build a prototype system based on a homogeneous array of
radio-connected nodes and an additional entity with a higher magnitude of com-
puting power. This central entity then controls the data collection from the nodes
and executes a custom localization algorithm, based on probabilistic methods and
aKalmanfilter. Wehaveevaluatedoursystembothbysimulationswithidealinput
data and by real-world measurements. The results show that the system is able to
track and update the location estimates, but due to the heavy multipath effect it is
onlycapableofverymoderateimprovements.
iv
Preface
I would like to express my deepest gratitude to everyone who helped me during
thesepastmonths. First,tomysupervisorsatARM,AmyasPhillipsandHugoVin-
cent; and to my professor, Koen Langendoen. Thank you for all your help, insight,
but most importantly, for your infinite patience. I would like to thank my family
andmyfriendsinBudapest,inCambridge,andinDelftfortheirgreatsupport. Es-
peciallyBeus, Re´ka, Shanti, Sza´dda´m, Ba´lint, KriszandTomi–thepeopleofdorm
roomsSCH1514andSCH408,whereIspentmostofmydaysandnightstypingout
the words of my thesis, until the Sun came up. I would also like to thank Paul´ına,
Andrea,Ade´landGabiforpolishingmywritingsonaregularbasis. Finally,aword
ofthankstoallthegreatwritersandmusiciansthatprovidedsomesortofinspira-
tionorapeaceofmindduringthelonghoursofwriting.
ZsoltKocsi-Horva´th
Delft,TheNetherlands
4thJanuary2013
v
vi
Contents
Contents
1 Introduction 1
1.1 Projectdescription. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2 ProblemStatement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3 Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.4 Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 Background 5
2.1 Wirelessnetworks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 RadioProtocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 Localizationmethods . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.4 Locationandprobability . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.5 BrieflyontheKalmanfilter . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.6 Examplesystemsandapplications . . . . . . . . . . . . . . . . . . . . 15
3 Design 17
3.1 Mainthesisscenario . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Introducingthecentralentity . . . . . . . . . . . . . . . . . . . . . . . 18
Radiotransmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Initialcoordinatesandreliabilityvalues . . . . . . . . . . . . . . . . . 20
3.2 Localizationprocess . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Representationofthecurrentsystemstate . . . . . . . . . . . . . . . . 21
Convertingsignalinformationtodistance . . . . . . . . . . . . . . . . 22
CustomlocalizationalgorithmwithKalmanfilter . . . . . . . . . . . . 24
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Contents
4 Implementation 29
4.1 Nodeshardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
mbedLPC1768 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Radiomodule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
4.2 Nodesoftware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
SignalsurveyusingtheChibistack . . . . . . . . . . . . . . . . . . . . 32
Modularsoftwaredevelopment . . . . . . . . . . . . . . . . . . . . . . 33
Commandsandactions . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
RealTimeOSandthreads . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.3 Centralentitysoftware . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Generatinganalternatedatabase . . . . . . . . . . . . . . . . . . . . . 37
Kalmansubsystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
5 Evaluation 41
5.1 Configurationandmethodology . . . . . . . . . . . . . . . . . . . . . . 41
Nodearrangement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Systemparameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Selectedscenarios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
5.2 Analysingresults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Locationupdates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
ConfiguringtheKalmanfilter . . . . . . . . . . . . . . . . . . . . . . . 48
Sequences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Convergence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Theadvantageofdiverseinput . . . . . . . . . . . . . . . . . . . . . . 51
Comparingmeasuredandtheoreticalcases . . . . . . . . . . . . . . . 52
Anoteonerrors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
6 Conclusion 55
FutureWork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Appendix 58
A.1 Localizationsystemoutputfigures,fullsize . . . . . . . . . . . . . . . 60
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