Table Of ContentWissenschaftliche Reihe
Fahrzeugtechnik Universität Stuttgart
Philipp Bergmeir
Enhanced Machine Learning
and Data Mining Methods
for Analysing Large Hybrid
Electric Vehicle Fleets based
on Load Spectrum Data
Wissenschaftliche Reihe
Fahrzeugtechnik Universität Stuttgart
Reihe herausgegeben von
M. Bargende, Stuttgart, Deutschland
H.-C. Reuss, Stuttgart, Deutschland
J. Wiedemann, Stuttgart, Deutschland
Das Institut für Verbrennungsmotoren und Kraftfahrwesen (IVK) an der Universi-
tät Stuttgart erforscht, entwickelt, appliziert und erprobt, in enger Zusammenarbeit
mit der Industrie, Elemente bzw. Technologien aus dem Bereich moderner Fahr-
zeugkonzepte. Das Institut gliedert sich in die drei Bereiche Kraftfahrwesen, Fahr-
zeugantriebe und Kraftfahrzeug-Mechatronik. Aufgabe dieser Bereiche ist die Aus-
arbeitung des Themengebietes im Prüfstandsbetrieb, in Theorie und Simulation.
Schwerpunkte des Kraftfahrwesens sind hierbei die Aerodynamik, Akustik (NVH),
Fahrdynamik und Fahrermodellierung, Leichtbau, Sicherheit, Kraftübertragung
sowie Energie und Thermomanagement – auch in Verbindung mit hybriden und
batterieelektrischen Fahrzeugkonzepten.
Der Bereich Fahrzeugantriebe widmet sich den Themen Brennverfahrensent-
wicklung einschließlich Regelungs- und Steuerungskonzeptionen bei zugleich
minimierten Emissionen, komplexe Abgasnachbehandlung, Aufladesysteme und
-strategien, Hybridsysteme und Betriebsstrategien sowie mechanisch-akustischen
Fragestellungen.
Themen der Kraftfahrzeug-Mechatronik sind die Antriebsstrangregelung/Hybride,
Elektromobilität, Bordnetz und Energiemanagement, Funktions- und Softwareent-
wicklung sowie Test und Diagnose.
Die Erfüllung dieser Aufgaben wird prüfstandsseitig neben vielem anderen unter-
stützt durch 19 Motorenprüfstände, zwei Rollenprüfstände, einen 1:1-Fahrsimulator,
einen Antriebsstrangprüfstand, einen Thermowindkanal sowie einen 1:1-Aero-
akustikwindkanal.
Die wissenschaftliche Reihe „Fahrzeugtechnik Universität Stuttgart“ präsentiert
über die am Institut entstandenen Promotionen die hervorragenden Arbeitsergeb-
nisse der Forschungstätigkeiten am IVK.
Reihe herausgegeben von
Prof. Dr.-Ing. Michael Bargende Prof. Dr.-Ing. Jochen Wiedemann
Lehrstuhl Fahrzeugantriebe, Lehrstuhl Kraftfahrwesen,
Institut für Verbrennungsmotoren und Institut für Verbrennungsmotoren und
Kraftfahrwesen, Universität Stuttgart Kraftfahrwesen, Universität Stuttgart
Stuttgart, Deutschland Stuttgart, Deutschland
Prof. Dr.-Ing. Hans-Christian Reuss
Lehrstuhl Kraftfahrzeugmechatronik,
Institut für Verbrennungsmotoren und
Kraftfahrwesen, Universität Stuttgart
Stuttgart, Deutschland
Weitere Bände in der Reihe http://www.springer.com/series/13535
Philipp Bergmeir
Enhanced Machine
Learning and Data
Mining Methods
for Analysing Large
Hybrid Electric Vehicle
Fleets based on Load
Spectrum Data
Philipp Bergmeir
Stuttgart, Germany
Zugl.: Dissertation Universität Stuttgart, 2017
D93
Wissenschaftliche Reihe Fahrzeugtechnik Universität Stuttgart
ISBN 978-3-658-20366-5 ISBN 978-3-658-20367-2 (eBook)
https://doi.org/10.1007/978-3-658-20367-2
Library of Congress Control Number: 2017961103
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„ForTina.“
Acknowledgements
I would like to thank all those people who made this thesis possible and an
unforgettableexperienceforme.
First,IwouldliketoacknowledgemygratitudetoProf.Dr.-Ing.MichaelBar-
gende,myadvisorattheUniversityofStuttgart,forhisgreatsupportandhis
permanentcommitmentinthedoctoralprogram“PromotionskollegHYBRID”
in which I was participating. Without him, I probably would not have been
given the chance to write this thesis as part of a collaboration between the
UniversityofStuttgart,theEsslingenUniversityofAppliedSciences,andthe
DaimlerAG.
IalsooweProf.Dipl.-Ing.JürgenNonnast,myadvisorattheEsslingenUniver-
sityofAppliedSciences, agreatdebtofgratitude: Hewasalwayswillingto
listentomeandhelpedmewithtechnicalaswellasorganizationalquestions.
Healsogavemetheopportunitytodesignandtogivemyownlecturesabout
DataMiningattheDepartmentofInformationTechnology.
Next, I would like to thank Prof. Dr.-Ing. Oliver Sawodny for his interest in
thisworkandforjoiningthedoctoralcommitee.
IwouldliketoexpressmydeepsenseofgratitudetoDr.ChristofNitsche,my
advisoratDaimlerAG,forhiscontinuousadviceandencouragementhegave
tomethroughoutthefouryearsIspentonthisthesis. Ithankhimforhispa-
tience, motivation, and enthusiasm. His systematic guidance and experience
helpedmeinallthetimeofresearchandwritingofthisthesis.
MyverysincerethanksalsogoestothewholedepartmentRD/PGHatDaimler
AG for offering me the opportunity to work on a thrilling industrial research
projectregardinghybridelectricvehicles. Namely,IwanttothankPeterAnt-
ony,myteamleaderatDaimlerAG,andtheheadsofthedepartmentRD/PGH
duringmyresearchtime, Dr.UweKellerandJochenStrenkert, fortheirsup-
port,especiallyinorganizationalmatters.
For many fruitful discussions and for supporting me in programming tasks,
myspecialthanksgoestomycolleaguesGauthamRaju,VishalRatra,andKir-
ankumarReddyfromMercedes-BenzResearchandDevelopmentIndia.
VIII Acknowledgements
Furthermore, IalsowanttoexpressmygratitudetotheMinistryforScience,
ResearchandArtsBaden-Württembergforfundingthedoctoralprogram“Pro-
motionskollegHYBRID”.
I am thankful to Dr. Andreas Theissler for being my co-lecturer in the two
courses “Introduction to Data Mining” and “Intelligent Data Analytics”. For
sure,Iamgoingtomissourexcellentcollaboration.
For their great technical support regarding the usage of the computer cluster
of the Esslingen University of Applied Sciences, I want to thank Dr. Adrian
ReberandAlexandruSaramet.
Moreover, I thank my friends and former, fellow Ph.D. students Dr. Daniel
GörkeandDr.AndreasHaagforallthestimulatingtechnicalandnon-technical
discussionswehadaswellasfortheathleticismweperformedinourleisure
times.
I am indebted to my cousin, Dr. Christoph Bergmeir, for his helpful advices,
inparticularregardingtheprocessofpublishingscientificpapers.
None of this would have been possible without the love and patience of my
family. That is why I take this opportunity to express the profound gratitude
from my deep heart to my parents, my grandparents, my sister, my brother-
in-law, mynieceLuisa, mynephewLukas, mysister-in-law, andmyparents-
in-law for their unconditional support throughout my whole life. They never
doubted any of my decisions, they helped me to clear my mind in stressful
times,andIamverygladtoknowthattheywillalwaysstandbyme,ingood
aswellasinbadtimes.
Finally, but most importantly, I would like to thank my beloved wife Tina.
Withoutherendlesssupport, itwouldhavebeenimpossibleformetomaster
thechallengeofwritingthisthesis. DearTina,thankyouforunderstandingall
ofmy decisionsandfor sticking byme, inspite ofthegeographical distance
betweenusduringthelastfewyears. ThankyouforlovingmejustthewayI
am.
Augsburg PhilippBergmeir
Contents
Acknowledgement.......................................... VII
ListofFigures .............................................. XIII
ListofTables ............................................... XVII
Acronyms................................................... XXI
Symbols..................................................... XXIII
Abstract ..................................................... XXIX
Kurzfassung................................................. XXXI
1 Introduction............................................. 1
1.1 Aims .............................................................. 2
1.2 Relatedwork...................................................... 2
1.3 Ownpublications................................................. 4
1.4 Outline............................................................ 5
2 Datafoundation ........................................ 7
2.1 Datasources...................................................... 7
2.1.1 On-boarddata: loadspectrumdata....................... 8
2.1.2 Off-boarddata: workshopdata ........................... 13
2.2 Preprocessingofdata ............................................ 15
2.3 Real-worlddatasets .............................................. 16
2.4 Conclusion........................................................ 17
3 Classifyingcomponentfailuresofavehiclefleet.... 19
3.1 Fundamentalsofclassification................................... 19
3.1.1 PerformanceMeasures.................................... 22
X Contents
3.1.2 The“classimbalanceproblem”........................... 23
3.2 Classificationmethods........................................... 25
3.2.1 Supportvectormachine(SVM) .......................... 25
3.2.2 Classificationtree ......................................... 33
3.2.3 Randomforest(RF)....................................... 38
3.2.4 Obliquerandomforest(ORF) ............................ 41
3.3 Fundamentalsoffeatureselection............................... 47
3.3.1 Variableimportanceintree-basedclassifiers ............ 50
3.3.2 Recursivefeatureelimination(RFE)..................... 53
3.4 AnewRFbasedclassificationandfeatureselectionframework 55
3.5 Casestudy: Classifyingcomponentfailuresofahybridcar
battery............................................................. 57
3.5.1 Parameteroptimization.................................... 58
3.5.2 Results ..................................................... 65
3.6 Conclusion........................................................ 81
4 Visualizingdifferentkindsofvehiclestressand
usage ..................................................... 83
4.1 Distanceanddissimilaritymeasures ............................ 84
4.1.1 Euclideandistance......................................... 84
4.1.2 Randomforestdissimilarity .............................. 85
4.2 Dimensionalityreductionmethods.............................. 87
4.2.1 PrincipalComponentsAnalysis .......................... 89
4.2.2 SammonMapping......................................... 90
4.2.3 LocallyLinearEmbedding................................ 91
4.2.4 Isomap ..................................................... 93
4.2.5 t-DistributedStochasticNeighbourEmbedding ......... 93
4.3 Casestudy: Dependenceofvehicleusageonoperatingcountry 97
4.3.1 Preprocessingandparametrization....................... 98
4.3.2 Results ..................................................... 99
Description:Philipp Bergmeir works on the development and enhancement of data mining and machine learning methods with the aim of analysing automatically huge amounts of load spectrum data that are recorded for large hybrid electric vehicle fleets. In particular, he presents new approaches for uncovering and de