muhammad faizul izreen othman ( cd 5134 )
TRANSCRIPT
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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
4.21 Deceleration test 60km/h 67
4.22 Deceleration test 40km/h 68
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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