DESIGN OF A SIX DEGREE OF FREEDOM MOTION PLATFORM FOR

VEHICLE DRIVING SIMULATOR APPLICATION

CHIEW YEONG SHIONG

A thesis submitted in fulfilment of the

requirements for the award of the degree of

Master of Engineering (Mechanical)

Faculty of Mechanical Engineering

Universiti Teknologi Malaysia

NOVEMBER 2009

iii

To my dearest and loving parents, brother, and all of my friends for their unending

love, sacrifices, and moral support

iv

ACKNOWLEDGEMENT

I wish to express my sincere appreciation to my supervisors, Associate

Professor Dr. Mohamad Kasim Abdul Jalil and Dr. Mohamed Hussein for the

invaluable advice and guidance throughout this research. Their encouragement and

dynamic ideas enabled the research to be carried out successfully.

I also would like to thank Dr. Mohd. Zarhamdy, Mr. Shamsul Bahri, Mr.

Kang, Mr. Hii and a number of faculty members who have unselfishly shared their

time and knowledge with me.

Last but not least, I wish to give thanks to my research colleagues and

seniors, for their caring and support during the many trying moments. Thank you for

being there.

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ABSTRACT

This research presents the design and development of a six degree of freedom

(6-DOF) motion platform for vehicle driving simulator application in Universiti

Teknologi Malaysia. The development processes include reviews of driving

simulator technology and design configurations, development of motion platform

mathematical modeling and simulation, control algorithm development and

validation of simulation results. The motion platform design is based on Stewart

platform design configuration. It was mathematically modeled using inverse

kinematics to control the kinematic behaviours of the motion platform. A

visualisation tool, SimMechanics was used to validate the motion platform motions

cues virtually. A Proportional-Integral-Derivative (PID) control algorithm for

motion platform actuators control was developed and tested. The motion platform

prototype was constructed and interfaced with simulation model through data

acquisition system to perform 6-DOF vehicle motion. The prototype was tested and

the kinematic performance of the prototype is validated. The results show that the

motion platform can be used for driving simulator application.

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ABSTRAK

Penyelidikan ini bertujuan untuk mereka bentuk dan membangunkan satu

pelantar gerakan untuk penyelaku pacuan kenderaan yang dapat bergerak dalam

enam darjah kebebasan (6-DOF) di Universiti Teknologi Malaysia. Proses

pembangunan yang terlibat di dalam penyelidikan ini adalah kajian berkaitan

teknologi simulasi memandu, konfigurasi rekaan, pembangunan model matematik

dan simulasi pelantar gerakan, pembangunan algoritma kawalan dan pengesahan

keputusan simulasi. Rekabentuk pelantar gerakan adalah berdasarkan konfigurasi

pelantar Stewart. Model matematik pelantar gerakan ini telah dibuat dengan

menggunakan kinematik songsang untuk mengawal kelakuan kinematiknya. Alatan

gambaran SimMechanics telah digunakan untuk mengesahkan pergerakan pelantar

gerakan. Pengawal algoritma Terbitan-Kamiran-Berkadaran (PID) untuk pelantar

gerakan telah dibangunkan dan diuji. Prototaip pelantar gerakan telah dibina dan

diperantaramuka dengan aturcara penghubungan model simulasi untuk bergerak

dalam arah 6-DOF. Prototaip telah diuji dan pengesahan prestasi kinematik pelantar

gerakan telah dilakukan. Keputusan telah menunjukkan bahawa pelantar gerakan ini

boleh digunakan untuk penyelaku pacuan kenderaan.

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TABLE OF CONTENTS

CHAPTER SUBJECTS PAGE

TITLE PAGE i

DECLARATION OF ORIGINALITY ii

DEDICATION iii

ACKNOWLEDGEMENTS iv

ABSTRACT v

ABSTRAK vi

CONTENTS vii

LIST OF TABLES xii

LIST OF FIGURES xiii

LIST OF SYMBOLS xvii

LIST OF APPENDICES xix

CHAPTER 1 INTRODUCTION

1.1 Preface 1

1.2 Problem Statement 2

1.3 Objective of Study 4

1.4 Scope of Study 4

1.5 Research Methodology 4

1.5.1 Mechanism Design 5

1.5.2 Control System Design 5

1.5.3 System Integration 7

1.5.4 Summary 7

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1.6 Research Contributions 8

1.7 Gantt Chart 8

1.8 Thesis Organization 9

CHAPTER 2 LITERATURE REVIEW

2.1 Introduction 10

2.2 Driving Simulator Classification 10

2.2.1 The Daimler-Benz Driving Simulator 11

2.2.2 National Advanced Driving Simulator 12

2.2.3 Toyota Driving Simulator 13

2.2.4 Mid-Level Driving Simulator 14

2.3 Motion Platform Configuration 16

2.3.1 5-Axis Motion Platform 16

2.3.2 Stewart Platform 17

2.3.3 Parallel Cable Drive 18

2.3.4 Motion Platform for Amusement

Devices 19

2.3.5 Mechanical Actuated Motion Platform 20

2.3.6 Summary: - Selection of Motion

Platform Design Configuration 21

2.4 Motion Platform Control Strategy 21

2.4.1 Motion Platform Kinematics Study: -

Inverse Kinematics 22

2.4.2 Proportional-Integral-Derivative (PID)

Controller 24

2.4.3 PID Tuning: - Ziegler-Nichols Method 25

2.5 MATLAB/ Simulink: - SimMechanics 26

2.6 Summary 28

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CHAPTER 3 MOTION PLATFORM DESIGN AND SYSTEM

CONFIGURATION

3.1 Introduction 29

3.2 Motion Platform Requirement 29

3.3 Product Design Specification and Limitation 30

3.4 Conceptual Design 34

3.4.1 Design Concept 1 34

3.4.2 Design Concept 2 34

3.4.3 Design Concept 3 35

3.4.4 Design Concept 4 36

3.4.5 Design Concept 5 36

3.5 Design Evaluation 37

3.6 Modifications and Detail Design 38

3.7 Motion Platform System Layout 39

3.8 Summary 41

CHAPTER 4 MOTION PLATFORM MODELING AND SIMULATION

4.1 Introduction 42

4.2 Inverse Kinematic Model (IKM) 42

4.3 Independent Vehicle Dynamic Model 44.

4.4 SimMechanics Motion Platform Generation

Process 46

4.5 Interfacing: - Simulation and Data Acquisition

System 49

4.6 Single Motor Control Model (SMCM) 53

4.7 Motion Platform Graphical User Interface

(MPGUI) 54

4.8 Summary 55

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CHAPTER 5 RESULTS AND DISCUSSIONS

5.1 Introduction 57

5.2 Inverse Kinematic and SimPlatform Simulation

Results 57

5.2.1 Motion Platform Idle Position 59

5.2.2 Motion Platform Rotational Movement 59

5.2.3 Motion Platform Translational

Movement 61

5.2.4 Motion Platform Combined Motions 63

5.3 Proportional-Integral-Derivative Controller

(PID Controller) Tuning 65

5.3.1 Ziegler-Nichols PID Tuning Results 66

5.3.2 Heuristic Tuning 68

5.4 Actual Motion Platform Simulation 71

5.4.1 Simulink Profiler: - Model

Optimization 71

5.4.2 Motion Platform Hardware and

Simulation Integration 73

5.4.3 Experimental Results on Motion

Cueing 75

5.4.4 Motion Platform Kinematic Calibration

Using Total Station 77

5.4.5 PID Controller for Motion Platform 82

5.4.6 Results of PID Controller for Sinusoidal

Motion Trajectory 84

5.5 Summary 85

CHAPTER 6 CONCLUSION AND RECOMMENDATIONS

6.1 Conclusion 87

6.2 Recommendations 88

REFERENCES 91

xi

APPENDICES A - L 97

LIST OF PUBLICATIONS 221

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LIST OF TABLES

TABLE NO. TITLE PAGE

2.1 Ziegler-Nichols PID tuning parameters 26

3.1 Desirable motion platform motion limits 30

3.2 Actuators location calculation 32

3.3 Evaluation criteria 37

5.1 Simulation input 58

5.2 Proportional, Integral and Derivative value for P, PI

and PID controller

65

5.3 Calibration test results 79

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LIST OF FIGURES

FIGURE NO. TITLE PAGE

1.1 Virtual reality fixed-base driving simulator 3

1.2 Fixed-base driving simulator 4

1.3 Design process 5

1.4 Control system design process 6

1.5 Methodology overview 7

1.6 Gantt chart 8

2.1 Driving simulator classification 11

2.2 Daimler-Benz driving simulator with extended

lateral motion system

12

2.3 The NADS in IOWA University 13

2.4 Toyota driving simulator 14

2.5 One of the configuration of 5DT driving simulator 15

2.6 Honda driving simulator 15

2.7 FTM driving simulator 15

2.8 5-axis motion platform 17

2.9 The first flight simulator that uses Stewart platform

for operation

18

2.10 Stewart platform kinematics structure: SPS (Left)

and UPS (Right)

18

2.11 Parallel cable drive motion base prototype 19

2.12 Arrangement of amusement device 20

2.13 Mechanical actuated motion platform 20

2.14 Vector diagrams for Stewart platform 23

2.15 Stewart platform with slider bar control 27

2.16 SimMechanics Stewart platform model 27

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3.1 Vehicle dynamics (Roll, pitch, yaw, surge, sway and

heave)

30

3.2 Workspace of the upper platform 31

3.3 Motion platform side view with estimated

dimensions

31

3.4 Motion platform actuators position from top view 33

3.5 Design concept 1 34

3.6 Design concept 2 35

3.7 Design concept 3 35

3.8 Design concept 4 36

3.9 Design concept 5 37

3.10 Modification of final concept A to B, B to C 38

3.11 Motion platform system layout 40

4.1 Inverse kinematic model (IKM) 43

4.2 Subsystems in inverse kinematic model 44

4.3 iUTMVDM with IKM 45

4.4 CAD to SimMechanics transformation sequence 46

4.5 SimMechanics block model 47

4.6 Motion platform model in CAD and SimMechanics 47

4.7 Setting up the joint actuator block with cylindrical

block

48

4.8 Sequence of motion platform collapsing (without

joint actuator blocks)

48

4.9 Machine environmental block 48

4.10 Complete SimPlatform with inverse kinematic

model

49

4.11 S-function: - a bridge connecting simulation and

hardware

50

4.12 Advantech PCI 1723 - ODAQ 51

4.13 Motor driver - MD30B 51

4.14 Motor driver input signals - PWM and digital 52

4.15 Output signal from PCI 1723 during forward and

reverse actuations

52

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4.16 Advantech PCI 1712 - IDAQ 53

4.17 Potentiometer and limit switch 53

4.18 Single motor control model (SMCM) 54

4.19 Motion platform graphical user interface (MPGUI) 55

5.1 Motion platform in SimMechanics and actuator’s

location

58

5.2 SimPlatform at idle position 59

5.3 SimPlatform at X angle 20 degree (α = 20°) 60

5.4 SimPlatform at Y angle 20 degree (β = 20°) 60

5.5 SimPlatform at Z angle 10 degree (γ = 10°) 61

5.6 SimPlatform in X-axis 0.2 meter (δx = 0.2m) 62

5.7 SimPlatform in Y-axis 0.2 meter (δy = 0.2m) 62

5.8 SimPlatform in Z-axis 0.2 meter (δz = 0.2m) 63

5.9 SimPlatform in α, β = 20°, δz = 0.2m 63

5.10 SimPlatform in δx, δy = 0.1m, δz = 0.2m 64

5.11 SimPlatform in α, β, γ = 10°, δx, δy, δz = 0.1m 64

5.12 P controller, Kp = 4.8, the system oscillates 66

5.13 P controller, Kp = 2.4 67

5.14 PI controller, Kp = 2.16, Ki = 2.833 67

5.15 PID controller, Kp = 2.88, Ki = 6.295, Kd = 0.3294 68

5.16 PID controller, Kp = 2.88, Ki = 1, Kd = 0.3294 69

5.17 PID controller, Kp = 2.88, Ki = 1, Kd = 0.3294 70

5.18 PID controller, Kp = 2.5, Ki = 0, Kd = 0.3294 70

5.19 PID controller, Kp = 2.5, Ki = 0.02, Kd = 0.3464 71

5.20 Simplified inverse kinematic model 72

5.21 Simulink profile report for original inverse

kinematic model simulation

73

5.22 Simulink profile report for simplified inverse

kinematic model simulation

73

5.23 Motion platform complete setup 74

5.24 Motion platform position according to Table 5.1 75

5.25 Equipment setup for calibration test 78

5.26 Location of targets on the upper platform 78

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5.27 Total station positioning system 79

5.28 Motion platform in idle position 80

5.29 Motion platform position when δx = 0.2m 81

5.30 Motion platform position when β = 20° 81

5.31 Motion platform position when γ = 20° 81

5.32 Actuator 1 with PID controller, Kp = 2.5, Ki = 0.02,

Kd = 0.3464

82

5.33 Actuator 1 with P controller, Kp = 1 and ±0.5mm

error band

84

5.34 Actuator 1 motion tracking 85

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LIST OF SYMBOLS/ ABBREVIATION

Pθ - Angles between and (°) 1P 2P

Bθ - Angles between and (°) 1B 2B

Pr - Upper platform radius (m)

Br - Lower platform radius (m)

iP - Location of actuators connections to upper platform

iB - Location of actuators connections to lower platform

α - Roll/ Rotation in X-axis (°)

β - Pitch/ Rotation in Y-axis (°)

γ - Yaw/ Rotation in Z-axis (°)

x - Upper platform position in X-axis (m)

y - Upper platform position in Y-axis (m)

z - Upper platform position in Z-axis (m)

il - Leg/ actuator length (m)

dB - Position of frame {P}

iP p - Vector describing position with respect to frame {P} iP

iBb - Vector describing position with respect to frame {B} iB

iB q - Leg vector with respect to frame {B}

RRP - Orientation matrix with respect to frame {B}

pX - Axis perpendicular to line connecting and 1P 6P

BX - Axis perpendicular to line connecting and 1B 6B

iλ - Angles between and (°) 1PP pX

iΛ - Angles between and (°) 1BB BX

xviii

YR - Rotation matrix (Z-axis)

PR - Rotation matrix (Y-axis)

RR - Rotation matrix (X-axis)

{B} - Frame {B}/ Lower Platform

{P} - Frame {P}/ Upper Platform

CAD - Computer-Aided Design

DAQ - Data Acquisition System

DOF - Degree of Freedom

HYSIM - Highway Driving Simulator

IDAQ - Input Data Acquisition

IKM - Inverse Kinematic Model

iUTMVDM - Independent Universiti Teknologi Malaysia Vehicle

Dynamic Model

LVDT - Linear Variable Differential Transformer

MPGUI - Motion Platform Graphic User Interface

NADS - National Advanced Driving Simulator

ODAQ - Output Data Acquisition

PID - Proportional-Integral-Derivative (Kp, Ki, Kd)

POT - Potentiometer

PWM - Pulse Width Modulation

SimPlatform - SimMechanics Motion Platform

SMCM - Single Motor Control Model

SPS - Spherical-Prismatic-Spherical

TCP/IP - Transmission Control Protocol/ Internet Protocol

TMC - Toyota Motor Corporation

UPS - Universal Joint-Prismatic-Spherical

UTMVDM - Universiti Teknologi Malaysia Vehicle Dynamic Model

VTI - Swedish National Road and Transport Research Institute

xix

LIST OF APPENDICES

APPENDIX TITLE PAGE

A Existing Driving Simulators 97

B Evaluation Chart 100

C Engineering Drawing 103

D Advantech PCI 1723 135

E Electronic Circuit 137

F Motor Driver - MD30B 149

G Advantech PCI 1712 148

H SMCM - S-function 151

I MPGUI - S-function 161

J Kinematic Calibration Test 1, 2, 3 183

K Calibration Results Calculation 202

L Error Band - S-function 208

CHAPTER 1

INTRODUCTION

1.1 Preface

Driving simulator has a history of several decades and has been used widely

throughout the world. One of the earliest driving simulators dated back in 1970s,

when General Motors, Virginia Polytechnic Institute and State University did the

pioneering work on human-in-loop driving simulations [1]. The Federal Highway

Administration driving simulator (HYSIM) begun operation for human factors work

later in 1983 [2]. This is then followed by the development of the VTI driving

simulator with extensive motion system by Swedish National Road and Transport

Institute in Linkoping on 1984 [3]. Other automobile manufacturers and research

institute such as the Daimler-Benz, DRI, Ford Research laboratory and IOWA

University also begun their own driving simulator development since the mid of

1980s.

Driving simulators are often used for educational and research purposes.

Driving simulators’ capability in producing a virtual driving environment resembling

real driving condition can be used to train novice drivers before they are exposed to

the real world [4]. Aside from that, driving simulators are important in data

collection for road safety research, human factor study, vehicle system development

and also traffic control device development [5]. These allow designers, engineers as

well as ergonomists, to bypass the design and development process of detailed

2

mockups of the automobile interiors for human factor and vehicle performance

studies.

1.2 Problem Statement

Road safety has always been a major concern for the Malaysian Government.

The rapid increase in motor vehicle ownership in combination with the relatively

young age of the populations and wide mix of vehicle types in the recent years have

resulted in a significant increase of road safety problems. Various engineering

approaches have been taken by the Government to overcome the problem, including

proactive actions, reactive actions, road maintenance and building new roads [6]. In

conjunction with the effort in the proactive actions, a research in developing a

driving simulator was started in 2002, in Universiti Teknologi Malaysia by the

Engineering Visualisation Research Group (EngViz). The driving simulator will

provide the platform for future research related to road safety and transport. At the

end of the first stage research work, a fixed-base driving simulator with visual

database and a generic vehicle dynamic model [7]. Figure 1.1 shows the result of the

first stage research work. This research work is the second stage and was aimed to

design and integrate a motion platform to the existing fixed-base driving simulator.

While driving a vehicle, a driver experiences the ride and handling characteristics of

the vehicle through motion cues due to angular and linear accelerations of the vehicle

chassis. The motion platform for driving simulator is a mechatronic equipment that

is capable of giving the realistic feeling of an actual vehicle to the drivers [8].

Motion platform varies in design depending on the design configurations, mechanism

used, motion properties and number of degrees of freedom (DOF). To integrate a

motion platform to the fixed-base driving simulator, a suitable motion platform must

be design and construct. This design process involves motion platform mechanism

design and construction, control system design and integration of the motion

platform with the existing driving simulator system. The mechanism design and

construction is aimed to design and construct the actual motion platform which is

suitable for the purposes. Control system design involves the mathematical modeling

and control algorithm development which describes the designed motion platform

3

mathematically and to control it. Finally, the integration work is to combine the

actual motion platform and its mathematical model with the previous fixed-base

driving simulator.

Figure 1.1: Virtual reality fixed-base driving simulator.

1.3 Objective of Study

The objectives of the research are to design and construct a motion platform

and to develop an algorithm of controlling a six degrees of freedom motion platform

for vehicle driving simulator application. The research also verifies and validates the

results based on published journals and simulation package. The motion platform is

aimed to integrate with the fixed-base driving simulator [7] shown in Figure 1.2.

a. Virtual Database

b. Driving Cabin c. Vehicle Dynamic Model

4

Figure 1.2: Fixed-base driving cabin.

1.4 Scope of Study

1. To develop the motion platform mathematical model and system control

using MATLAB/ Simulink.

2. To design and construct motion platform based on 6-DOF.

3. To develop a digital PID algorithm for controlling a 6-DOF motion platform.

4. To verify and validate the motion platform’s motion cues using graphical

display of the motion platform and comparing with actual model.

1.5 Research Methodology

The motion platform development process is divided into three major

components; mechanism design, control system development and system integration.

1.5.1 Mechanism Design

The specification and system requirements of the motion platform design

were first critically reviewed. This is followed by review of various existing motion

platform design configurations. Different motion platform configurations were

studied and analyzed. The most suitable configuration was chosen based on the

5

system requirements developed for this research [9]. Figure 1.3 shows the general

mechanism design process.

Figure 1.3: Design process.

1.5.2 Control System Design

The control system design is aimed to accurately control the 6-DOF motion

platform using Proportional-Integral-Derivative (PID) controller. The motion

platform was first mathematically modeled. From the mathematical model of the

motion platform, the control variable was identified. In this research, the control

variable is the linear motion of the actuation unit for the motion platform. Validation

and verification of the mathematical model was carried out to determine the accuracy

of the mathematical model representing the motion platform. Next is to determine

the control strategy and develop a digital PID algorithm for motion platform.

Simulation was carried out through the assistance of MATLAB/ Simulink. The

performance of the PID controller in the motion platform was then evaluated and

improved. The process of control system design is shown in the Figure 1.4 [10].

Establishing Scopes and Objective

Literature Review

Conceptual Design

Initial Analysis

Final Conceptual Design

Evaluation

6

Figure 1.4: Control system design process.

In addition to the modeling and controller design, the research work also

involves the development of a data acquisition system (DAQ). Generally, data

acquisition is the sampling of the real world to generate data that can be manipulated

by a computer. The data acquisition system is designed to measure and log

parameters. A data acquisition system consists of hardware and software. The

hardware includes sensors, cables and other electronics component. As for the

software components, it consists of the data acquisition logic and the analysis

software. This software can be developed using various programming languages

such as BASIC, C, Fortran, Java or Pascal. Data logging carried out by a data

acquisition system, can be used to measure parameters such as sensor’s voltage

which is the information for motor position. These data are then stored for analysis

to improve the quality of the system [11].

1.5.3 System Integration

The system integration stage is very much dependent on the work done in the

previous two. This stage can only begin when both mechanism design and control

Establishing Goals

Derivation of Mathematical Model

Development of Control Algorithm

Simulation

Evaluation

Validation or Verification

7

system design are done. The developed control system needs to be integrated with

the designed mechanism in order to obtain the desired output of the system.

1.5.4 Summary

The Figure 1.5 shows the summary of the research methodology.

Figure 1.5: Methodology overview.

1.6 Research Contribution

The contributions of this research are:

1. This research is the initial attempt to control the motion platform in real time.

In this research, Proportional-Integral-Derivative control algorithm (PID) is

used and the details will be explained in Chapter 2.

Validation or Verification

Control System Design and Simulation

Integration

Mechanism Design

Design and Development of a 6 DOF Motion Base

8

2. To develop the frame of integrating motion platform with other driving

simulator subsystem such as the visual database and vehicle dynamic model.

3. Acquiring the technology behind the motion platform control and design.

This motion platform was developed from scratch and the use of computer

application software was minimal to avoid ‘black-box’ in the development

process.

1.7 Gantt Chart

This research was scheduled for 18 months duration. Thus careful planning

is required for the research to proceed and to be completed. Figure 1.6 shows the

Gantt chart of the research.

Figure 1.6: Gantt chart.

1.8 Thesis Organization

This thesis is divided into six chapters. The first Chapter gives an overall

introduction of the research project. It consists of preface, problem statement,

objective of study, scope of study and research methodology. The Chapter ends with

Month

Work 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Obtain Title & Discuss

Objectives

Literature Studies

Log & Progress Writing

Math Formulation

Modeling

Design Selection & Purchasing

Programming

Control and Construction

Validation and Implementation

Report Writing

9

the research contribution and a Gantt chart showing the planning for the research.

Chapter 2 presents the fundamental concepts and literature review pertaining to the

focus of study. This includes the classification of driving simulators, different

motion platform configurations, and mathematics (kinematics) involved in motion

platform design. A brief review on the simulation software and the control strategy

used is also presented. Chapter 3 focuses on the motion platform mechanism design.

It clarifies the design requirements and design specifications. The conceptual

designs and design evaluation are shown. At the end of Chapter 3, the final design

concept and the motion platform system layout is shown. Chapter 4 discusses

simulation and system integration development process of the inverse kinematic

model, independent vehicle dynamic model, S-function, SimMechanics model,

single motor control model and motion platform Graphical User Interface (MPGUI).

The integration of the control system with the motion platform is also briefly

discussed. Chapter 5 discusses the simulation results together with validations with

real time test results. The PID tuning test results are also shown in Chapter 5. The

complete motion platform system with calibration of the motion cues are presented

in the end of Chapter 5. Finally, Chapter 6 concludes the research and several

recommendations on further research works are given.