IDENTIFICATION OF VEHICLE ROLLOVER CONDITIONS AND

ACTIVE ROLL CONTROL STRATEGIES

AMRIK SINGH A/L PHUMAN SINGH

UNIVERSITI TEKNOLOGI MALAYSIA

IDENTIFICATION OF VEHICLE ROLLOVER CONDITIONS AND ACTIVE

ROLL CONTROL STRATEGIES

AMRIK SINGH A/L PHUMAN SINGH

A project report submitted in partial fulfilment of the

requirements for the award of the degree of

Master of Engineering (Mechanical Engineering)

Faculty of Mechanical Engineering

Universiti Teknologi Malaysia

JANUARY 2012

iii

To my beloved mum and family

Thank you for all kindness and sacrifices you made for me.

iv

ACKNOWLEDGEMENTS

First and foremost, I would like to express my deep gratitude to my project

supervisor Associate Professor Dr. Intan Zaurah Mat Darus for her guidance,

advices, and valuable comments. It has been an honor and a privilege to have the

opportunity carry out research work under her guidance. I also want to thank Dr.

Shirish Padmakar Patil for sharing his knowledge and providing guidance in vehicle

dynamics.

This study was fully supported by Ministry of Higher Education (MoHE)

under Skim Latihan Akademik IPTA (SLAI) and Universiti Teknikal Malaysia

Melaka (UTeM). Indeed, this research project gave me a valuable experience and an

excellent insight into vehicle dynamics and control field.

Special appreciation goes to my mum for her continuous support and

encouragement. Without her I cannot be where I am today. I am also grateful to my

fellow postgraduate friends for their contributing ideas and assistance.

v

ABSTRACT

This research presents the development of active roll control strategies to

prevent vehicle rollover. The dynamic model representing the vehicle behaviour was

first developed and then modelled in Matlab/SIMULINK environment. The tire

model integrated to the vehicle model was represented using look up table method.

The validity of the vehicle model was verified using CarSim software for double lane

change and fishhook manoeuvres. The validation results show strong agreement

between the vehicle model and CarSim software. Parametric study was done to

investigate the effect of the driver inputs and vehicle parameters on the roll behavior

of the vehicle. The effect of the variation of these properties on the vehicle roll angle

and load transfer ratio was discussed. Two fuzzy logic based active roll control

schemes were developed using active suspension and active front steering. For active

roll control using active suspension, the effectiveness of feedforward fuzzy and

combination of feedback and feedforward fuzzy in reducing the rollover propensity

were evaluated. For active front steering, feedback fuzzy control was incorporated

with the vehicle model to assess the performance of the active front steering in

reducing vehicle rollover propensity for fishhook and step steer manoeuvres. Both of

the proposed control strategies had shown significant enhancement in avoiding

vehicle rollover and hence improving the safety of vehicle occupants.

vi

ABSTRAK

Kajian ini membentangkan pembangunan strategi kawalan gulingan aktif untuk

mengelakkan golekan kenderaan. Pada permulaan kajian, model dinamik yang

mewakili kelakuan kenderaan dibangunkan dan kemudian dimodelkan dalam

pperisian Matlab/ SIMULINK. Model tayar digabungkan dengan model kenderaan

diwakili dengan menggunakan kaedah jadual carian. Model kenderaan disahkan

dengan menggunakan perisian CarSim untuk gerakan perubahan lorong dua kali dan

gerakan mata kail. Keputusan pengesahan menunjukkan persetujuan yang kuat antara

model kenderaan dan perisian CarSim. Kajian parametrik dilakukan untuk mengkaji

kesan input pemandu dan parameter kenderaan ke atas kelakuan gulingan kenderaan.

Dua skim kawalan gulingan aktif berasaskan logik kabur telah dibangunkan dengan

menggunakan sistem gantungan aktif dan sistem kemudi depan yang aktif. Untuk

kawalan guling yang aktif menggunakan sistem gantungan aktif, keberkesanan logik

kabur suapan ke hadapan dan gabungan logik kabur maklum balas dan logik kabur

suapan ke hadapan dalam mengurangkan kecenderungan golekan dinilai. Untuk

sistem kemudi depan yang aktif, kawalan logik kabur maklum balas telah

diperbadankan dengan model kenderaan untuk menilai prestasi sistem kemudi depan

yang aktif dalam mencegah golekan kenderaan. Kedua-dua strategi kawalan yang

dicadangkan telah menunjukkan peningkatan yang ketara dalam mengelakkan

golekkan kenderaan dan dengan itu meningkatkan keselamatan pengguna kenderaan.

vii

TABLE OF CONTENTS

CHAPTER TITLE PAGE

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENTS iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES x

LIST OF FIGURES xi

LIST OF ABBREVIATIONS xvi

LIST OF SYMBOLS xvii

1 INTRODUCTION 1

1.1 Background 1

1.2 Problem Statement 2

1.3 Objectives of the Research 3

1.4 Scope of the Research 3

1.5 Research Methodology 4

1.6 Organization of the Thesis 6

2 LITERATURE REVIEW 8

2.1 Vehicle Rollover 8

2.2 Rollover Resistance Rating 8

2.3 Vehicle Rollover Avoidance System 9

2.3.1 Passive Vehicle Rollover Avoidance System 9

2.3.2 Active Vehicle Rollover Avoidance System 10

viii

2.3.2.1 Active Suspension 10

2.3.2.2 Active Front Steering 11

2.3.2.3 Active Brake 13

2.4 Vehicle Rollover Detection and Performance Criteria 14

2.5 Vehicle Handling and Rollover Test 15

2.6 Control System for Active Roll Control 17

2.7 Fuzzy Logic Control 17

3 METHODOLOGY 20

3.1 Vehicle Modelling 20

3.1.1 Full Vehicle Model 20

3.1.2 Vehicle Modelling Assumptions 21

3.1.3 Development of Mathematical Modelling 22

3.1.4 Tire Model 29

3.1.5 Vehicle Model Subsystem Interactions 29

3.2 Validation of Vehicle Model 30

3.2.1 Validation for Double Lane Change at 80 km/h

and Fishhook at 50 km/h

32

3.3 Test to Evaluate Vehicle Rollover Propensity 33

3.3.1 Fishhook Manoeuvre 33

3.4 Development of Active Roll Control System 35

3.4.1 Basic of Fuzzy Logic Control 35

3.4.2 Active Roll Avoidance System based on Fuzzy

Logic Control via Active Suspension

39

3.4.2.1 Feedforward Fuzzy Control 40

3.4.2.2 Relationship between Roll Motion and

Road Steering Wheel Angle and Vehicle

Longitudinal Velocity

40

3.4.2.3 Active Suspension 41

3.4.2.4 Feedforward Fuzzy Logic Control 42

3.4.2.5 Feedback Fuzzy Logic Control 45

3.5 Active Roll Avoidance System based on Fuzzy Logic

Control via Active Front Steering

48

3.5.1 Load Transfer Ratio 50

3.5.2 Reference Vehicle Model 51

ix

4 RESULTS AND DISCUSSION 52

4.1 Validation for Double Lane Change Test at 80 km/h 51

4.2 Validation for Fishhook Test at 50 km/h 55

4.3 Parametric Studies 58

4.4 Performance Evaluation of Active Roll Control using

Active Suspension

63

4.5 Performance Evaluation of Active Roll Control using

Active Front Steering

71

4.5.1 Active Roll Control Performance for Fishhook

Test at 72.4 km/h

71

4.5.2 Active Roll Control Performance for 140 Deg

Step Steer Test at 60 km/h

77

5 CONCLUSION AND RECOMMENDATIONS 82

5.1 Conclusion 82

5.2 Recommendations 83

REFERENCES 84

x

LIST OF TABLES

TABLE NO. TITLE PAGE

2.1 Vehicle handling test 15

3.1 SUV parameters 31

3.2 Rule table for fuzzy logic control 37

3.3 Rule table for feedforward fuzzy control 44

3.4 Rule table for feedback fuzzy control 47

3.5 Rule table for feedback fuzzy control 50

4.1 Root mean square for fishhook test at 64.4 km/h 66

4.2 Root mean square for 140 deg step steer test at 60 km/h 68

4.3 Root mean square for double lane change manoeuvre at

80 km/h

71

xi

LIST OF FIGURES

FIGURE NO. TITLE PAGE

1.1 Rollover resistance rating 2

1.2 Research procedure flowchart 5

1.3 Project gantt chart 6

2.1 Static stability factor 9

2.2 Active front steering (Klier et al., 2004) 11

2.3 Active differential braking (Chen and Peng, 2001) 13

2.4 NHTSA fishhook test (Weimert) 16

2.5 Modified ISO 3888-2 course layout (Forkenbrock et al.,

2005)

17

2.6 Feedback fuzzy logic control strategy (March and Shim,

2006)

18

2.7 Feedforward fuzzy logic control strategy (Khajavi et al.,

2009)

19

2.8 Fuzzy tune PID control strategy (Xinpeng and

Xiaocheng, 2007)

19

3.1 Full vehicle model 21

3.2 Schematic diagram for quarter car model for front left

side

22

3.3 3 DOF vehicle handling model 24

3.4 Schematic diagram for forces acting on the front left

wheel

27

3.5 Tire lateral force depending on tire normal load and slip

angle

29

xii

3.6 Interaction between vehicle subsystems 30

3.7 CarSim software graphical user interface 31

3.8 Screen shot of the animation for double lane change

manoeuvre

32

3.9 NHTSA fishhook manoeuvre description (Boyd, 2004) 34

3.10 Hand wheel steer angle versus lateral acceleration 34

3.11 NHTSA fishhook hand wheel steering input 35

3.12 Basic control structure of fuzzy logic 35

3.13 Membership functions 37

3.14 Fuzzy control rules using Matlab environment 37

3.15 Fuzzy control design process 39

3.16 Feedforward roll control strategy 40

3.17 Active suspension 42

3.18 Road steering wheel angle membership functions for

feedforward fuzzy control

43

3.19 Vehicle longitudinal velocity membership functions for

feedforward fuzzy control

43

3.20 Normalised counter roll moment membership functions

for feedforward fuzzy control

44

3.21 Combination of feedback and feedforward roll control

strategy

45

3.22 Roll angle error membership functions for feedback

fuzzy control

46

3.23 Roll angle error rate membership functions for feedback

fuzzy control

46

3.24 Normalised counter roll moment membership functions

for feedback fuzzy control

47

3.25 Active front steering roll control strategy 48

3.26 Roll angle error membership functions 49

3.27 Roll angle error rate membership functions 49

3.28 Normalised road wheel steer angle membership

functions

49

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3.29 Vehicle reference model 51

4.1 Road wheel steering angle for double lane change at 80

km/h

52

4.2 Yaw rate response for double lane change at 80 km/h 53

4.3 Lateral acceleration response for double lane change at

80 km/h

54

4.4 Roll angle response for double lane change at 80 km/h 54

4.5 Roll rate response for double lane change at 80 km/h 54

4.6 Y versus X trajectory for double lane change at 80 km/h 55

4.7 Road wheel steering angle for fishhook test at 50 km/h 56

4.8 Yaw rate response for fishhook test at 50 km/h 56

4.9 Lateral acceleration response for fishhook test at 50

km/h

57

4.10 Roll angle response for fishhook test at 50 km/h 57

4.11 Y versus X trajectory for fishhook test at 50 km/h 58

4.12 Roll angle response for fishhook test at different

longitudinal velocities

59

4.13 Load transfer ratio for fishhook test at different

longitudinal velocities

59

4.14 Roll angle response for fishhook test at different vehicle

center of gravity height

60

4.15 Load transfer ratio for fishhook test at different vehicle

center of gravity height

60

4.16 Roll angle response for fishhook test at different driver

steering input

61

4.17 Load transfer ratio for fishhook test at different driver

steering input

61

4.18 Roll angle response for fishhook test at different track

width

62

4.19 Load transfer ratio for fishhook test at different track

width

62

4.20 Roll angle response for fishhook test at different spring

stiffness

63

4.21 Load transfer ratio for fishhook test at different spring

stiffness

63

xiv

4.22 Roll angle response for fishhook test at 64.4 km/h 64

4.23 Roll rate response for fishhook test at 64.4 km/h 64

4.24 Vehicle body vertical acceleration response for

fishhook test at 64.4 km/h

65

4.25 Vehicle body vertical acceleration response for

fishhook test at 64.4 km/h

65

4.26 Roll angle response for 140 deg step steer test at 60

km/h

66

4.27 Roll rate response for 140 deg step steer test at 60 km/h 67

4.28 Vehicle body vertical acceleration response for 140 deg

step steer test at 60 km/h

67

4.29 Vehicle body vertical displacement response for 140

deg step steer test at 60 km/h

68

4.30 Roll angle response for double lane change manoeuvre

at 80 km/h

69

4.31 Roll rate response for double lane change manoeuvre at

80 km/h

69

4.32 Vehicle body vertical acceleration response for double

lane change manoeuvre at 80 km/h

70

4.33 Vehicle body vertical displacement response for double

lane change manoeuvre at 80 km/h

70

4.34 Road wheel steer angle for fishhook test at 72.4 km/h 72

4.35 Roll angle response for fishhook test at 72.4 km/h 72

4.36 Load transfer ratio for fishhook test at 72.4 km/h 72

4.37 Front left tire normal load for fishhook test 72.4 km/h 73

4.38 Front right tire normal load for fishhook test at 72.4

km/h

73

4.39 Rear left tire normal load for fishhook test at 72.4 km/h 74

4.40 Rear right tire normal load for fishhook test at 72.4

km/h

74

4.41 Lateral velocity response for fishhook test at 72.4 km/h 75

4.42 Yaw rate response for fishhook test at 72.4 km/h 75

4.43 Sideslip angle response for fishhook test at 72.4 km/h 76

4.44 Vehicle trajectory response for fishhook test at 72.4

km/h

76

xv

4.45 Road wheel steer angle for 140 deg step steer test at 60

km/h

77

4.46 Roll angle response for 140 deg step steer test at 60

km/h

77

4.47 Load transfer ratio for 140 deg step steer test at 60 km/h 78

4.48 Front left tire normal load for 140 deg step steer test at

60 km/h

78

4.49 Front right tire normal load for 140 deg step steer test at

60 km/h

79

4.50 Lateral velocity response for 140 deg step steer test at

60 km/h

79

4.51 Yaw rate response for 140 deg step steer test at 60 km/h 80

4.52 Sideslip angle response for 140 deg step steer test at 60

km/h

80

4.53 Vehicle trajectory response for 140 deg step steer test at

60 km/h

81

xvi

LIST OF ABBREVIATIONS

ARC - Active Roll Control

AFS - Active Front Steering

DOF - Degree of Freedom

ISO - International Organization for Standardization

NCAP - New Car Assessment Program

NHTSA - National Highway Traffic Safety Administration

PD - Proportional Derivative

PI - Proportional Integral

PID - Proportional Integral Derivative

SSF - Static Stability Factor

SUV - Sport Utility Vehicle

xvii

LIST OF SYMBOLS

a - Distance of sprung mass C.G. from front axle

ay - Lateral acceleration at C.G

Csfl - Front left suspension damping coefficient

Csfr - Front right suspension damping coefficient

Csrl - Rear left suspension damping coefficient

Csrr - Rear right suspension damping coefficient

Fafl - Front left actuator force

Fafr - Front right actuator force

Farl - Rear left actuator force

Farr - Rear right actuator force

Fsfl - Front left suspension force

Fsfr - Front right suspension force

Fsrl - Rear left suspension force

Fsrr - Rear right suspension force

Ftfl - Front left tire force

Ftfr - Front right tire force

Ftrl - Rear left tire force

Ftrr - Rear right tire force

Fxfl - Front left tire longitudinal force

Fxfr - Front right tire longitudinal force

xviii

Fxrl - Rear left tire longitudinal force

Fxrr - Rear right tire longitudinal force

Fyfl - Front left tire lateral force

Fyfr - Front right tire lateral force

Fyrl - Rear left tire lateral force

Fyrr - Rear right tire lateral force

Fzfl - Front left tire normal force

Fzfr - Front right tire normal force

Fzrl - Rear left tire normal force

Fzrr - Rear right tire normal force

g - Acceleration due to gravity

h - Height of vehicle C.G. from ground

Iw - Tire moment of inertia

Ix - Roll moment of inertia

Iy - Pitch moment of inertia

Iz - Yaw moment of inertia

Ksfl - Front left suspension stiffness

Ksfr - Front right suspension stiffness

Ksrl - Rear left suspension stiffness

Ksrr - Rear right suspension stiffness

Ktfl - Front left tire stiffness

Ktfr - Front right tire stiffness

Ktrl - Rear left tire stiffness

Ktrr - Rear right tire stiffness

m - Total mass of vehicle

ms - Sprung mass

xix

mufl - Front left unsprung mass

mufr - Front right unsprung mass

murl - Rear left unsprung mass

murr - Rear right unsprung mass

Mzfl - Front left tire aligning moment

Mzfr - Front right tire aligning moment

Mzrl - Rear left tire aligning moment

Mzrr - Rear right tire aligning moment

R - Tire radius

Sfl - Front left tire longitudinal slip

Sfr - Front right tire longitudinal slip

Srl - Rear left tire longitudinal slip

Srl - Rear right tire longitudinal slip

Tbfl - Front left wheel brake torque

Tbfr - Front right wheel brake torque

Tbrl - Rear left wheel brake torque

Tbrr - Rear right wheel brake torque

Tdfl - Front left wheel drive torque

Tdfr - Front right wheel drive torque

Tdrl - Rear left wheel drive torque

Tdrr - Rear right wheel drive torque

Vx - Vehicle longitudinal velocity at C.G

Vy - Vehicle lateral velocity at C.G

w - Track width

Zrfl - Front left road profile

Zrfr - Front right road profile

xx

Zrrl - Rear left road profile

Zrrr - Rear right road profile

Zs - Sprung mass vertical displacement at body C.G.

Zsfl - Front left sprung mass displacement

Zsfr - Front right sprung mass displacement

Zsrl - Rear left sprung mass displacement

Zsrr - Rear right sprung mass displacement

Zufl - Front left unsprung mass vertical displacement

Zufr - Front right unsprung mass vertical displacement

Zurl - Rear left unsprung mass vertical displacement

Zurr - Rear right unsprung mass vertical displacement

- Front left tire sideslip angle

- Front right tire sideslip angle

- Rear left tire sideslip angle

- Rear right tire sideslip angle

δ - Steering angle at road wheel

ωfl - Front left wheel angular velocity

ωfr - Front right wheel angular velocity

ωrl - Rear left wheel angular velocity

ωrr - Rear right wheel angular velocity

- Pitch angle at the body C.G.

- Roll angle at the body C.G.

- Yaw angle at body C.G.

CHAPTER 1

INTRODUCTION

1.1 Background

Rollover is one of most life threatening crash incident compared to other type

of vehicle crashes. Vehicle roll motion occurs when there is normal load transfer

from the inner wheel to the outer wheel. The wheel normal load transfer is due to the

lateral force that comes from severe driving inputs especially in cornering with high

speed, from impact with other road vehicle, curbs, and from lamp post or sign

boards. Generally, vehicle rollover may be divided to two types, namely untripped

and tripped rollover. Tripped rollover takes place when the vehicle skid of the road

and make a contact with obstacles such as curb and guardrail or the wheel hitting a

port hole which yields a roll moment that may cause the vehicle to rollover. In

contrast, untripped rollover occurs on the road under severe driving condition such as

high speed obstacle avoidance test manoeuvre.

In the assessment of vehicle safety in terms of rollover resistance, the vehicle

type is the plays important role. In Figure 1.1, the rollover resistance rating for

different types of vehicles given that the vehicle is involved in single vehicle crash

by the NCAP are presented. It can be seen that vehicles with higher center of gravity

such as sport utility vehicles have lower rollover resistance rating and hence this type

of vehicles are more prone to rollover. Although, the vehicle type plays main

contribution in rollover, other factors such as the driver behaviour, road condition,

and environment should not be neglected.

2

Figure 1.1 Rollover resistance rating

In an effort to avoid vehicle rollover, passive rollover avoidance system was

introduced at first. Passive rollover avoidance system is the when the vehicle detects

the possibility of vehicle rollover and gives warning to the driver so that the driver

could take corrective action to prevent vehicle rollover. Some of the passive rollover

avoidance systems are early warning safety device (Rakheja and Piche, 1990),

dynamic rollover threshold (Dahlberg, 2000), and time to rollover metric (Chen and

Peng, 1999). The passive rollover avoidance system was still driver dependent. As an

improvement to this, active roll control system was introduced. Active roll control

system is where the vehicle detects the possibility to vehicle rollover and the vehicle

itself takes the corrective to avoid the impending vehicle rollover. Various types of

control system have been developed to enhance vehicle roll dynamics and prevent

rollover. Active suspension (Hudha et al., 2008; Sorniotti and D’Alfio, 2007), active

steering (Shim, T. et al., 2008; Ackerman et al., 1999), and active braking

(Wielenga, 1999; Solmaz et al., 2006) are among the control strategies that have

been investigated by the researchers to enhance the vehicle rollover resistance.

1.2 Problem Statement

It is important that the vehicle roll motion is reduced to avoid rollover risk

and hence increase the safety of the vehicle occupant. There is possibility that the

vehicle rollover can be recovered if the driver is skilful enough but it is more than

3

impossible for a normal driver to avoid rollover when the vehicle is driven at its

handling limits. For example, stunt drivers are enable to maintain the vehicle on two

wheels without allowing the vehicle to rollover but this is not possible for a normal

driver. For this reason, the active roll control system should be incorporated during

the development phase in automotive industry. In this thesis, two types of active roll

control system, namely active suspension control and active front wheel steering will

be implemented on a vehicle dynamics model to evaluate their capabilities to prevent

vehicle rollover.

1.3 Objectives of the Research

This research focuses on the development of the vehicle roll control

strategies. The two objectives of this thesis are as follows:

To develop vehicle model and identify the conditions that cause the vehicle

to rollover.

To develop active roll control strategies based on active suspension and

active front steering using fuzzy control scheme.

1.4 Scope of the Research

The scope of this thesis is as follow:

Development of the vehicle model in Matlab/SIMULINK to represent the

rollover behavior of the vehicle.

4

Validation of vehicle model with CarSim software for double lane change

and fishhook maneuvers.

Identify the causes that lead to vehicle rollover, e.g., the driver steering wheel

angle, vehicle speed, vehicle and suspension properties.

Development of active roll control strategies:

o Active roll control system based on active suspension using

feedforward fuzzy control, and combination of feedback and

feedforward fuzzy control schemes.

o Active roll control system based on active front steering using

feedback fuzzy control scheme.

1.5 Research Methodology

The research methodology considered in this thesis is described in Figure 1.2.

First, the literature study of previous works is done on vehicle rollover, vehicle

modeling, active roll control strategies and fuzzy logic control schemes. A vehicle

model that is capable in accurately predicting the vehicle roll behavior is developed

in Matlab/SIMULINK. The vehicle model is then validated CarSim software for

double lane change and fishhook maneuvers. The vehicle responses in terms of the

vehicle roll angle, roll rate, lateral acceleration, yaw rate and vehicle trajectory for

both simulation of the vehicle model and CarSim software were compared to present

the validity of the vehicle model used in this thesis. Parametric studies are done using

the validated vehicle model to indentify the conditions that may lead to vehicle

rollover. The parameters that investigated are stiffness of the suspension spring,

height of vehicle center of gravity, track width, vehicle longitudinal speed, and driver

steering wheel angle input. Two active roll control strategies were developed based

on active suspension system and active front wheel steering using fuzzy logic control

scheme. The proposed control strategies are implemented on the vehicle model and

5

simulation test were done. The performance evaluation was carried out for both

proposed control strategies.

Figure 1.2 Research procedure flowchart

The Gantt chart for Master Project 1 and Master Project 2 are presented in

Figure 1.3.

Yes

Start

Development of Vehicle Handling Model

Vehicle Model Verification with CarSim

Verified?

Parametric Study for Vehicle Rollover Condition Identification

Development of Active Roll Control System

Active Roll Control System Performance Evaluation

End

Literature Review

No

6

Figure 1.3 Project gantt chart

1.6 Organization of the Thesis

This thesis consists of five chapters. A brief outline of contents of the thesis is

as follows:

Chapter 1 presents the introduction to research which includes the background,

problem statement, objectives, scope, and brief research methodology. The research

procedure flowchart and gantt chart are also included in this chapter.

Chapter 2 focuses on literature study on vehicle rollover. Firstly, previous work and

passive and active rollover avoidance systems were discussed. This was followed by

the discussion on the vehicle rollover detection methods and performance criteria.

7

The vehicle handling tests were also addressed in this chapter. Literature study on the

type of control scheme implemented in active roll control strategies was included.

Chapter 3 is devoted to comprehensive vehicle modelling and proposed control

strategy description. Firstly, the assumptions made in developing the vehicle model

are stated. This is followed by mathematical modelling of the full vehicle including

non linear tire models. The vehicle dynamics tests used to evaluate vehicle rollover

propensity are described in this chapter. Last but not least, the proposed rollover

control strategies using active suspension and active front steering were described.

Chapter 4 focuses on the evaluation of the active roll control strategies using active

suspension and active front steering. Firstly, the validation of the vehicle model with

CarSim software for double lane change and fishhook tests. Then, the performance

evaluation was done on the for active roll control using active suspension and active

steering.

Chapter 5 provides summary of the research works which includes conclusion and

suggestions for future research works.

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