Design and Simulation of an ABS Control Scheme for a Formula Student Prototype Mechanical ...

107 Pages·2014·2.77 MB·English

Design and Simulation of an ABS Control Scheme
for a Formula Student Prototype
João Pedro Carrapiço Ferro
Thesis to obtain the Master of Science Degree in
Mechanical Engineering
Supervisor: Professor Paulo Jorge Coelho Ramalho
Co-supervisor: Professor João Miguel da Costa Sousa
Examination Committee
Chairperson:
Supervisor:
May 2014
2
Acknowledgments
The work developed in this thesis a continuance of the knowledge and innovative spirit acquired dur-
ing the three years spent in Projecto FST. For their unflagging help, suggestions and encouragement,
I would like to specially thank my team-mates, with whom I’ve designed, spent sleepless nights, dis-
cussed, learned, travelled, cheered, celebrated and shared the same passion for engineering and mo-
torsports.
To my thesis supervisor Professor Paulo Oliveira and co-supervisor Professor Joa˜o Sousa, whose
insight,knowledgeandadvicewereequallyimportantonpursuingthisambitiousbuthighlyenlightening
challenge.
To my friends, for their motivation, everlasting friendship and comprehension when I just could not
bethere.
Tomyfamily,fortheirinestimablesupportandincessantbelief,notonlyduringthiswork,butthrough-
out the entire degree. A special dedication to my grandfather, who provided me the inspiration and
engineeringgenes.
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Abstract
Anti-lock braking system (ABS) has the objective of controlling wheel slip so that maximum friction
force is attained while maintaining adequate steerability and stability during hard braking. Beyond the
inestimable contribution to road safety, ABS may also be used in racecars as a driving-aid system to
enhancebrakingperformance.
ThisthesisaddressesthedesignofanABSseekingtheimplementationonaFormulaStudent racing
prototype. Theproposedschemeutilizesacascadecontrolarchitecture: aPID-typefuzzycontrollerwith
aTakagi-Sugeno-Kangfuzzyinferencesystemisdesignedforwheelslipcontrolontheouterloop,whilst
abrakepressurePDcontrollerisadoptedintheinnerloop. Wheelslipestimationsolution,resortedon
acomplementaryfilter,isalsodeveloped.
The performance of the ABS is assessed with a full vehicle model, sustained by vehicle dynamic
principles. The model is integrated with brakeline dynamics and a tire friction model based on reliable
experimental data. Straight line brake simulations are performed and results are evaluated in terms of
brakingefficiencyandcontrolrobustness,underdifferentandvariableconditions. Acompletelapwithin
atypicalFormulaStudent circuitisalsosimulated,forthecaseswithandwithoutABS.
Keywords:
anti-lock braking system (ABS), Formula Student, fuzzy controller, PID controller,
wheelslipestimation,vehiclemodel,tiremodel
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Resumo
O sistema de travagem ABS (do ingleˆs anti-lock braking system) tem o objetivo de controlar o escor-
regamento da roda de forma a atingir a ma´xima forc¸a de atrito, mantendo dirigibilidade e estabilidade
suficientes durante uma travagem brusca. Para ale´m da inestima´vel contribuic¸a˜o para a seguranc¸a
rodovia´ria, o sistema ABS pode tambe´m ser usado em carros de competic¸a˜o como sistema de as-
sisteˆnciaa` conduc¸a˜oparamelhorarodesempenhoemtravagem.
Esta tese trata do projeto de um sistema ABS para implementac¸a˜o num proto´tipo de competic¸a˜o
do tipo Formula Student. O esquema proposto utiliza uma arquitetura de controlo em cascata: um
controlador fuzzy do tipo PID com um sistema de infereˆncia fuzzy do ge´nero Takagi-Sugeno-Kang e´
projetado para o controlo do escorregamento da roda no anel exterior, enquanto para o anel interior e´
adotadoumcontroladordepressa˜odotipoPD.Umasoluc¸a˜odeestimac¸a˜oparaoescorregamentoda
roda,comrecursoaumasoluc¸a˜odefiltrocomplementar,e´ tambe´mdesenvolvida.
O desempenho do sistema ABS e´ avaliada com um modelo completo do ve´ıculo, sustentado nos
princ´ıpios da dinaˆmica de ve´ıculos. O modelo e´ integrado com a dinaˆmica da linha de travagem e um
modelo de atrito do pneu baseado em dados experimentais fidedignos. Simulac¸o˜es de travagem em
linharetasa˜oexecutadaseosresultadosexaminadosemtermosdeeficieˆnciadetravagemerobustez
decontrolo, sobcondic¸o˜esdiversasevaria´veis. E´ tambe´msimuladaumavoltacompletaaumcircuito
deFormulaStudent t´ıpico,paraoscasoscomesemABS.
Palavras-chave:
sistemadetravagemABS,FormulaStudent,controladorfuzzy,controlador
PID,estimac¸a˜odoescorregamentodaroda,modelodeve´ıculo,modelodepneu
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Contents
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii
Resumo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
ListofTables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
ListofFigures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiv
ListofSymbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvi
1 Introduction 1
1.1 BriefhistoryofABS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Motivation(FormulaStudent) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.4 Workcontributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.5 Outline. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 VehicleDynamics 7
2.1 GlobalOverview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 HorizontalDynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.3 VerticalDynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.3.1 LagrangeMethod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.3.2 VehicleLoads. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.3.3 InverseKinematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.3.4 TireVerticalLoad . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.4 WheelDynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.4.1 Free-bodydiagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.5 BrakelineDynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.5.1 Steady-stateequations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.5.2 Transientbehaviour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.5.3 HydraulicModulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3 TireModel 25
3.1 Typesofmodels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.1.1 PacejkaModel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
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3.1.2 BurkhardtModel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
3.1.3 NeuralNetworkModel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
3.2 ExperimentalData . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.3 DataFitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.3.1 MethodologyforPacejkaandBurckhardtmodels . . . . . . . . . . . . . . . . . . . 31
3.3.2 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
4 ABSOverview 35
4.1 ObjectivesofABS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.2 ABSComponents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4.3 WheelSlipControl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.3.1 LongitudinalSlipRatio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.3.2 ControlProblemDefinition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
4.3.3 Maindifficulties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
4.4 ControlMethods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
4.4.1 ThresholdControl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
4.4.2 PIDControl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
4.4.3 Sliding-modeControl. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
4.4.4 IntelligentControl. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
5 ProposedApproach 45
5.1 Problemdataandrequirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
5.1.1 FSRules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
5.1.2 Competitioncharacteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
5.1.3 FST05e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
5.2 ProposedControlStructure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
5.2.1 InnerLoop-BrakePressureController . . . . . . . . . . . . . . . . . . . . . . . . 48
5.2.2 OutterLoop-WheelSlipController. . . . . . . . . . . . . . . . . . . . . . . . . . . 49
5.3 DesignApproach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
6 ABSDesign 51
6.1 BrakePressureController . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
6.1.1 PIDOverview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
6.1.2 PWMConversion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
6.1.3 Open/closedloopstepresponse . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
6.1.4 PDDesign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
6.2 WheelSlipController. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
6.2.1 FISOverview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
6.2.2 FISDesign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
6.2.3 PIDGainsOptimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
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