muhammad faizul izreen othman ( cd 5134 )

8/12/2019 Muhammad Faizul Izreen Othman ( CD 5134 )

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UNDERSTEER PERFORMANCE ANALYSIS FOR FRONT WHEEL DRIVE (FF)SEDAN VEHICLE UNDER STEADY AND RIDE ROAD DRIVING CONDITION

MUHAMMAD FAIZUL IZREEN BIN OTHMAN

A report submitted in partial fulfillment of the requirements for the award of the degree

of Bachelor of Mechanical Engineering with Automotive

Faculty of Mechanical Engineering

UNIVERSITI MALAYSIA PAHANG

NOVEMBER 2010


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ii

SUPERVISORS DECLARATION

We hereby declare that we have checked this project and in our opinion this project is

satisfactory in terms of scope and quality for the award of the degree of Bachelor of

Mechanical with Automotive Engineering.

Signature :

Name of Supervisor : PROFESOR DR. HJ. ROSLI BIN ABU BAKAR

Position : Supervisor

Date :

Signature :

Name of Co-supervisor : MR. GAN LEONG MING

Position : Co-supervisor

Date :


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STUDENTS DECLARATION

I hereby declare that the work in this thesis is my own except for quotations and

summaries which have been duly acknowledged. The thesis has not been accepted

for any degree and is not concurrently submitted for award for other degree.

Signature : .

Name of Supervisor : MUHAMMAD FAIZUL IZREEN BIN OTHMAN

ID Number : MH 07038

Date :


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ACKNOWLEDGEMENT

I would like to thank ALLAH S.W.T for bless and guidance for me tocomplete this project. This acknowledgement also dedicated to Prof. Dr. Rosli bin

Abu Bakar, Mr. Gan Leong Ming, Mr. Faizul Syahidan Bin Rajuli, and Mr.

Muhamad Imran Bin Mohmad Sairaji who either directly or indirectly contributed

toward the material contained in this thesis.

Last but not least, I would like to thanks all university staffs, from

Mechanical Engineering Faculty for being so cooperative and not forgetting all my

fellow friends for the support, advice, information sharing and financial support.


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ABSTRACT

Research in the area of vehicle dynamics in the on-road skidding condition is limited.

The used methods generally are using simulation that the environmental elements thatinfluence the vehicle dynamics were ignored. The skidding condition is the influences

factors in handling the vehicle and user safety in order to achieve the safe and

controllable maneuver. The driver input and the responses in the skidding condition

have a limitation and range to have a safe maneuver. The purpose of this research is to

analyze the yaw stability in the understeer condition. To perform an investigation of

understeer performances in the real maneuver, the experiment that considered all the

noise from the surrounding that influence the vehicle has been done. The steady state

cornering, lane change, and straight line braking experiment was used to determine the

relationship between side slip angle and slip angle. Persona 1.6 (MT) equipped with the

RV-4 vector sensor, Gyroscopic sensor with DEWEtron Data acquisition system was

used as the test car and the apparatus for this experiment. Result obtains from theexperiment verified the vehicle stability in the understeer condition being achieve

between the theoretical and experimental data.


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ABSTRAK

Kajian mengenai dinamika kenderaan dalam situasi gelincir dalam keadaan pemanduan yang

sebenar adalah kurang. Kebanyakan dari kajian ini menggunakan simulasi dimana faktorsekeliling yang menpengaruhi dinamika kenderaan telah diabaikan. Keadaan gelincir

merupakan faktor yang mempengaruhi tahap kawalan kenderaan dan keselamatan penguna

untuk mendapatkan pergerakan kenderaan dalam kawalan dengan selamat. Tujuan kajian ini

adalah untuk menganalisis keupayaan kenderaan dalam situasi pergerakan dibawah kawalan

stering. Eksperimen mengenai situasi ini telah dijalankan untuk melihat keupayaan kenderaan di

dalam keadaan pemanduan sebenar dimana faktor persekitaran telah diambil kira. Pergerakan

kenderaan semasa mengambil selekoh yang jitu, penukaran haluan, dan penyahpecutan

kenderaan merupakan situasi yang dianalisis didalam exprimen ini telah digunakan untuk

mengenal pasti hubungan antara sudut gelincir tayar dan sudut gelincir badan kenderaan. Kereta

Proton Person 1.6 (MT) yang dilengkapi dengan pengera vektor dan sudut RV-4, pengera gyro

dan sistem pengumpul data DEWEtron telah dijadikan sebagai kereta pandu uji dan alatan

dalam menjalankan eksperimen ini. Keputusan dari hasil eksperiment telah digunakan untukmemastikan keseimbangan kenderaan dalan keadaan dibawah kawalan stering dan dibandingkan

dengan teori dinamika kenderaan.


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TABLE OF CONTENTS

SUPERVISORS DECLARATION ii

STUDENTS DECLARATION iii

DEDICATION iv

ACKNOWLEDGEMENT v

ABSTRACT vi

ABSTRAK vii

TABLE OF CONTENT viii

LIST OF TABLES xi

LIST OF FIGURES xiiLIST OF SYMBOLS xiv

LIST OF ABBREVIATION xv

CHAPTER 1 INTRODUCTION

1.1 Project Backgound 1

1.2 Problem Statement 2

1.3 Objective 3

1.4 Scopes 3

1.5 Hypothesis 3

1.6 Flow Chart 4

CHAPTER 2 LITERATURE REVIEW

2.1 Introduction 52.2 Overview of Skidding Problem 5

2.2.1 Traffic Accident 5

2.2.2 Future Challenge of Road Safety 8

2.3 Skidding Terminology 8

2.3.1 Sprung and Unsprung Mass 8

2.3.2 Vehicle Fix Coordinates 9

2.3.3 Vehicle Dynamics Stability Control 10

2.4 Vehicle Skid 13

2.4.1 Brake Skid 13


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2.4.2 Blow Skid 14

2.4.3 Power Skid 14

2.4.4 Cornering Skid 15

2.5 Understeer 16

2.5.1 Introduction of Understeer and Oversteer 16

2.5.2 Understeer Factor 17

2.6 Steering System 18

2.7 Vehicle Dynamics of Understeer 20

2.7.2 Range of Lateral Acceleration 26

2.8 Overview of Understeer Performance 27

2.8.1 Vehicle Dynamics Stability Control Based on GPS 27

2.8.2 Effect of The Front and Rear Weight Distribution Ratio ofaaaaaa..Formula Car During Maximum Speed Cornering on A Circuit 28

2.8.3 Sensitivity Analysis Of Side Slip Angle For Front Wheel

aaaa..Steering Vehicle For A Front Wheel Steering Vehicle: A

aaaa..Frequency Domain

29

2.8.4 Nonlinear Tire Lateral Force vs Slip Angle Curve Identification 31

2.8.5 Summary 32

CHAPTER 3 METHODOLOGY

3.1 Literature Study 33

3.2 Preparing Test Car With Sensor 33

3.2.1 DEWETRON Measurement 33

3.2.2 RV-4 Vector Sensor 35

3.2.3 Gyroscopic 35

3.3 Develop Procedure for Testing 36

3.3.1 Testing Scope 36

3.3.2 Preliminary Testing 37

3.3.3 Testing Procedure 38

3.4 Experimental Data Collection 44

3.5 Result Analysis on Ride Performance 45

3.5.1 Slip Angle 45

3.5.2 Steady State Cornering Analysis 46

3.5.3 Lane Change Test 48

3.5.4 Deceleration 48

CHAPTER 4 RESULT AND DISCUSSION

4.1 Steady State Cornering 49


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4.1.1 Constant Radius Different Velocity 49

4.1.2 Constant Radius Different Weight 54

4.1.3 Constant Velocity Different Radius 58

4.1.4 Relationship Between Body Slip Angle to the Slip Angle 61

4.2 Lane Change 62

4.3 Deceleration Test 66

CHAPTER 5 CONCLUSION AND RECOMMENDATION

5.1 Conclusion 70

5.2 Recommendation 71

REFFERENCES

APPENDICES

A Real Data Experiment 1 76

B Real Data Experiment 2 80

C Real Data Experiment 3 83

D Test Car Specification 86

E Gantt Chart 89


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LIST OF TABLES

Table No. Title Page

2.1 Road Accident Statistic (2009) 6

2.2 Road Accident by Road Type 7

2.3 Vehicle Steer Condition 23

3.1 Maximum Speed for Each Gear 39

3.2 Section Distance for lane Change 42

4.1 GPS Distance and Ackerman Steer Angle 49


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LIST OF FIGURES

Figure No. Title Page

2.1 Unsprung and Unsprung Mass 9

2.2 Car axis 9

2.3 Complete Bicycle Model 11

2.4 EPS Operation 12

2.5 Brake Skid 13

2.6 Blow Skid 14

2.7 Power Skid 14

2.8 Cornering Skid 15

2.9 Understeer and Oversteer Motion 16

2.10 Ackerman Turning Geometry 19

2.11 Slip Angle 20

2.12 Bicycle Model 21

2.13 Angle Diagram of Vehicle Slip 22

2.14 Steer Angle vs Speed 23

2.15 Yaw Rate Transfer Function 24

2.16 Low Speed Slip 25

2.17 High Speed Slip 25

2.18 Cornering Stiffness vs Slip Angle 29

2.19 Yaw rate sensitivity Analysis 30

2.20 Relation Ship Between lateral force to the Slip Angle 31

3.1 DEWETRON measurement 34

3.2 DEWEsoft acquisition software 343.3 RV-4 Vector Sensor 35

3.4 Gyroscopic Sensor 35

3.5 Testing Location 39

3.6 Lane Change road setup 42

3.7 Deceleration Reference Range 43

3.8 COG 45

3.9 Absolute GPS vehicle direction 46

4.1 Steer Angle vs Speed in constant Radius of 51.80m 50


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4.2 Lateral Acceleration vs Speed in Constant Radius of 51.80 51

4.3 Sea Level vs Vehicle Direction in Constant Radius of 51.80 51

4.4 Vehicle Direction vs Time 52

4.5 Vehicle Slip vs Speed in Constant Radius of 51.80m 52

4.6 Slip Angle vs Side Slip Angle in Constant Radius of 51.80m 53

4.7 Steer vs Lateral Acceleration in Constant Radius of 51.80m 54

4.8 Steer Angle vs Vehicle Mass in Constant Speed of 40km/h 55

4.9 Lateral Force vs Vehicle Mass in Constant Speed of 40km/h 56

4.10 Vehicle Slip vs Vehicle Mass in Constant Speed of 40km/h 56

4.11 Lateral Force vs Steer Angle in Constant Radius (51.80m)

and constant speed (40km/h)

57

4.12 Steer Angle vs Cornering Radius at constant speed of

40km/h

58

4.13 Lateral Acceleration vs Cornering Radius on constant speed

(40km/h)

59

4.14 Vehicle Slip vs Cornering Radius at constant speed 40km/h 59

4.15 Steer Angle vs Lateral Acceleration at constant speed

40km/h

60

4.16 Body Slip vs Slip Angle 61

4.17 Lane Change with ConstantSpeed of 30km/h 62

4.18 Lane Change with ConstantSpeed of 40km/h 63

4.19 Lane Change with Constant Speed of 60km/h 64

4.20 Deceleration test 90km/h 66




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LIST OF SYMBOL

ay Lateral Acceleration

b Distance Front Tyre To Center Of Gravity

c Distance Rear Tyre To Center Of Gravity

Fy Lateral Force

Fyf Front Lateral Force

Fyr Rear Lateral Force

g Gravity Acceleration (9.81m/s )

K Understeer Gradient

L Wheel Basem Mass

R Cornering Radius

S Radius Circumference

t Time

T Wheel Track

v Vehicle Speed

Vchar Characteristic Velocity

Wf Weight Front

Wr Weight Total

Wt Weight Rear

Slip Angle

Side Slip

Steer Angle

i Inner Steer Angle

o Outer Steer Angle

absolute vehicle direction angle

Cornering Stiffness


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LIST OF ABBREVIATION

ABS Anti-Lock Braking System

ADT Average Daily Traffic

ASR Anti-Slip Regulation

CG Center Of Gravity

COG Course Over Ground

DSC Vehicle Dynamic Stability Control

EPS Electronic Stability Program

ESC Electronic Stability Control

GPS Global Positioning SystemIIHS Insurance Institute For Highway SafetyNHTSA National Highway Traffic Safety Administration


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CHAPTER 1

INTRODUCTION

1.1 PROJECT BACKGROUND

The analysis of the vehicle performance in skidding condition is important and

many methods have been introduced in order to avoid the extreme accident that can

cause the serious injuries. Nowadays, systems for active control of vehicle handing are

standard equipment in many vehicles, such as anti-lock brake, traction control and yaw

control that improve active safety by controlling some key vehicle state during running

(Hac,A and Simpson,M.D. 2000). In this research, the relationship between vehicle

body slip and tyre slip angle has been determine by using on road experiment.

In order to maintain safe handling characteristics of vehicles, designers strive to

maintain consistent, predictable vehicle response to driver steering inputs in the entire

range of operation. The purpose of control is to bring the vehicle yaw rate response and

the vehicle slip angle into conformance with the desired yaw rate and slip angle. To

achieve this goal, vehicle actual response must be known (Haiyan,Z. and Cheng,H.

2008). But acquiring information on the vehicle side slip angle is not an easy task, sincethere is no physical effect that allows a determination of vehicle lateral movement using

a force measurement, as is the case for yaw rate. In this research the yaw rate will be

measure by gyroscopic sensor, the steer angle measured by RV-4 vector sensor and the

vehicle direction will be determined by using GPS.

In this research the performance of understeer condition is be analyzed in order

to guide the driver in vehicle maneuver. The stability of the car and the safety of the


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driver also the passenger can be ensure with the analysis of the vehicle performance

during understeer.

1.2 PROBLEM STATEMENT

Dynamics and performance of vehicles are related to the vehicle maneuver

system. The tyre is the only part of contact between the road and the vehicle, they are at

the main of vehicle handling and performance. When the vehicle moving, tyres are

required to produce the lateral forces that necessary for controlling the vehicle in

maintains the traction (T.D. Gillespie 1992). While the tyre maintains the traction, the

vehicle trajectory will be different to the steer angle input because of the slip angle.

When the vehicle in cornering with varies speed or in the acceleration, deceleration and

normal ride mode, there will be a change in the longitudinal axis and the local direction

of travel that also known as sideslip angle.

The driver does not have 100% control to the traction and the vehicle maneuver.

Under emergency conditions, several maneuvers, or extreme road conditions, the

imaginary movement is different to the real movement (Koo,S.L., Tan, H.S., and

Tomizuka,M. 2004). The differential of the tyre and longitudinal axis angle is due to the

car movement that will cause the unstable maneuver of the vehicle. This problem occur

when the traction between the road surface decrease and the moment of vehicle inertia.

The traction losses can cause difficulty to the driver to control the vehicle and increase

the potential of road accident.

Driver faces the problem of the handling and safety when the vehicle loss thetraction between the tyre and the road surface that cause by the existence of the slip

angle. The body slips influence the slip angle and the potential to lose the tyre grip that

contribute to traction loss. The relation of sideslip angle and the tyre slip angle is the

main goal to be determined, in order to achieve the perfect vehicle maneuver and to

maintain the car stability.


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1.3 OBJECTIVE

To analyze the yaw stability with determine the relationship between slip angle

and side slip angle in understeer condition of Front Drive (FF) sedan hatchback vehicle.

1.4 SCOPES

The project has to focus on few scopes in order to achieve the objectives:

i. Literature study on the topics related to the project.

ii. Preparations on the procedures for installation sensor and pre-testing.

iii. Run the experiment based on the procedures.

iv. Analysis the results gained on the steer angle and the body.

v. Final report preparation.

1.5 HYPOTHESIS

The steering angle in the understeer condition is influence by the lateral

force. The increasing of the side slip angle will reduce the percentage of the vehicle to

understeer.


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1.5FLOW CHART

Literature Review

Sensor Installation and DAS

Develop test Procedure

System

Operation

Testing

Data collection

Start

End

Performance Anal sis

Report Preparation

Validation data

Project Presentation

no

no

es

yes


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CHAPTER 2

LITERATURE REVIEW

2.1 INTRODUCTION

In this chapter the three main topics will be covered, first is the concept of

vehicle skid and will focus on understeer, second is the effect of the understeer that

influence driving maneuver. The third topics are the factor that leads to the contribution

to the vehicle understeer performance. In this chapter also will discuss about the test car

specification and the previous research about car understeer performance.

2.2 OVERVIEW OF SKIDDING PROBLEM

2.2.1 Traffic accident

Mustafa M.N has stated that the accident cause can be a combination of either

these three basic factors which are road user errors, road environment faults and vehicle

defects. In the engineering point of view, these factors below constitute to road and

roads environment that usually related to an accident:

Combination of traffic composition

The various types of vehicles that are used on the road are the combination of

small, medium and heavy vehicles. Road accident statistic shows that in 2009. Car is the

highest vehicle that contributes to the road accident with 68.16% follow by motorcycle

16.16% (Table 2.1). The cause of the no separation for the type of vehicle leads to the

road accident.


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Table 2.1: Road Accident Statistics (2009)

Type Casualties Percentage (%)

Motorcycle 113 962 16.16

Car 480 976 68.16

Heavy Vehicle/Bus 56 104 7.95

Others 54 581 7.73

Total 705 623 100

Source: Jabatan Keselamatan Jalan Raya Malaysia, (2009)

Improper intersection design

Improper design at intersection can cause significant increase of accident. In

2003, accident occurrence at intersection is the second after straight road which

constitute about 22% (inclusive of cross, T/Y and staggered junction) (Table 2.2). As an

example rear end collision usually cause by improper design of right turn which did not

provide enough storage lane for vehicle while wait to turn right. Other related issue to

improve design in lack of safe sight distance. From table 2.2 the average percentage

road accident that occur at the roundabout are 13.87% the inference that can be made on

this percentage is To maintain equilibrium as vehicle speed increases in a turn the

increased centrifugal force must be balanced by the steer angles and tire slip angles. If

there is greater compliance resulting in higher slip angles--at the front tires than the rear

tires, the vehicle is understeer. If there is greater compliance that resulting in higher slipangle at the rear tires than the front tires, the vehicle is oversteer (Fittanto,D.A., and

Senalik,A. 2004). The driver false response in either condition on handling the vehicle

may lead to the accident.


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Table 2.2:Road Accident by Road Type (2003)

Road Type Fatal Serious Total % ave

Straight 3 690 4 148 7 838 63.10

Roundabout 894 829 1 723 13.87

Bend 23 28 51 0.41

Cross Junction 215 457 672 5.41

T/Y Junction 576 1 424 2 000 16.10

Staggered Junction 36 78 114 0.92

Interchanges 12 11 23 0.19

Total 5 446 6 975 12 421 100

Source: Mustafa,M.N. (2005)

High Traffic Volume

High traffic volume is one of the contributors to traffic accident. It is found that

an increase in traffic volume associated with an increase in traffic accident. A studyconcluded that an accident along sections with the average daily traffic (ADT) of above

30,000 is about 47% higher than ADT less than 30,000. Not enough gaps in between

vehicles at intersection and less chance to overtake other motorist are some of the

concerns affected from high traffic volumes (Mustafa,M.N. 2005). The increasing of the

traffic volume influence the vehicle to decelerates and accelerates base on the traffic

volume intensity.

Vehicle Speed

With increase of road network and vehicles specification, most of new vehicle

will drove exceeding the posted speed limit. This may due to the availability and

visibility of existing road signage (Mustafa,M.N. 2005). Furthermore, none realistic

speed limit may impose to further increase in speeding motorist.


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2.2.2 Future Challenge of Road Safety

Ministry of Work Malaysia, MOWs tried to provide a better safety of road in

Malaysia alongside with the Government efforts to reduce traffic accident and to

achieve its targets. Although studies shown that causes to most of the accident is

because of the drivers themselves, MOWs always make it positive effort in order to

improve traffic accident by giving further stress on engineering aspect with proactive

and reactive action during design, construction and maintenance stage (Mustafa.M.N.

2005).

The major of vehicle that involve in an accident is car and in various type of

road. The human factor that leads to an accident is too subjective to be analyzed and the

ergonomic factor should be considered if the cases are involving humans.

The vehicle in ride condition will influence the focus of the driver, the ability of

controlling the vehicle during skidding condition, and this will influence the percentage

of the accident. In this paper the skidding condition properties will be determine the

dynamic factor that lead to the road accident.

2.3 SKIDDING TERMINOLOGY

2.3.1 Sprung And Unsprung Mass

The car is a type of vehicle and the vehicle dynamics is part of it. The vehicle

will move on a road surface and the dynamics encompasses the interaction of driver,vehicle, load, and the environment. The car is the lumped mass, and under the low

velocity the car can be represent as one lumped mass located at its center of gravity

(CG) with appropriate mass and inertia properties. For the ride condition the car will be

two lumped mass which the body is the sprung mass and the wheel are denoted as

unsprung mass (Figure 2.1) (Rill,G. 2009). The inertia of the sprung mass influence the

magnitude of the body slip (Bevly, D. M., Gerdes, J. C., Wilson, C. 2002)


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Figure 2.1:Unsprung and Sprung Mass

Source: Rill,G. (2009)

2.3.2 Vehicle Fix Coordinate

The car motions are define with reference to a right-hand orthogonal coordinate

system which is the fixed coordinate system (Gillespie,T.D. 1992). The origin of these

coordinate is at the CG and travel with the vehicle (Figure 2.2). The car motion are

describes by the velocity of forward, lateral, vertical, roll, pitch and yaw with respect to

the vehicle fixed coordinate system where the velocities are referred to the earth fixed

coordinate.

Figure 2.2:Car axis

Source: Gillespie,T.D. (1992)

S run mass

Uns run wei htSus ension

T re com ression

Wheel

bounce

Velocit


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2.3.3 Vehicle Dynamics Stability Control

Vehicle Dynamic Stability Control (DSC) system can stabilize the vehicle

behavior in emergency situations such as spinning, drift out and roll over (Tseng,H.E.

1999). It improves vehicle active safety and comfort greatly. DSC requires

measurements of yaw rate and vehicle sideslip angle. The yaw rate can easily be

measured by a gyro. Typically, the vehicle sideslip angle is either estimated with an

observer integrating the gyro and knowing the vehicle model, by using accelerometers

and integrating the lateral and longitudinal acceleration to determine the velocity or

some combination of the two (Hahn,J. 2002). These methods have drawbacks due to

errors arising from model and sensor uncertainties.

Global Positioning System

The global positioning system (GPS) allows the vehicle sideslip angle to be

determined without requiring a model of the system. GPS does have several drawbacks

(Ray,L 1995). The sample rate of most GPS receivers is 10 Hz, which is much lower

than the typical sample rates of accelerometers and gyros

(Bevly,D.M.,Gerdes,J.C.,Wilson,C. 2002). Additionally the GPS measurement contains

higher noise than traditional inertial sensors. This paper will show it is possible to

utilize the advantages of GPS while working within its limitations to accurately control

a vehicle. GPS has already proved effective when used for vehicle navigation and lane

keeping as well as estimating cornering stiffness and wheel slip. GPS has also been used

to measure yaw rate.

There are two main ways to control the lateral motion of a vehicle. The first is to

directly control the steer angle (steer-by-wire); the second is to control the longitudinal

force generated at each wheel by differential braking (Zhang,J.Z. and Tian,Z.H. 2009).

Steer-by-wire is more widely used for autonomous control of a vehicle because most

drivers would feel uncomfortable without a direct mechanical link between the steering

wheel and the tires. Differential braking is the method usually employed in vehicle

stability control systems. A problem arises, however, when choosing how to split the

braking force among the four tires. With GPS it is possible to determine the slip angle

muhammad faizul izreen othman ( cd 5134 )

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