DESIGN AND DEVELOPMENT OF A NEW

STABILIZATION MECHANISM FOR TWO-WHEELED

WHEELCHAIR

BY

TAREQ M. K. ALTALMAS

A thesis submitted in fulfilment of the requirement for the

degree of Master of Science (Mechatronic Engineering)

Kulliyyah of Engineering

International Islamic University Malaysia

JANUARY 2015

ii

ABSTRACT

This research embarks on designing a new mechanism for transforming a four-

wheeled wheelchair into a two-wheeled wheelchair. It is known that wheelchair

system is a main means of mobility for the disabled and the elderly. A normal four

wheels wheelchair has some limitations where the wheelchair user is too depending on

the helper, which reduces their mobility if the assistance is not available. The standard

wheelchair nowadays only caters for outdoor environment where the space is not a

constraint. Therefore, the two-wheeled wheelchair is proposed to encourage

independence where many common tasks such as pick and place things can be done

independently and is suitable to be used in confined space i.e. home, office or library.

The proposed two-wheeled wheelchair was modeled to mimics a double inverted

pendulum scenario where Link2 was introduced to cater for the human weight. To

increase the confidence level of the modeling stage, a virtual prototype of a two-

wheeled wheelchair was developed with a human model. Analysis of the model was

conducted and simulated to study the actuators requirement and response

performance. The mathematical models were then derived to represent the two-

wheeled wheelchair. It was achieved that the equations derived represents the system

as a highly nonlinear and unstable system. The complexity of the system was reduced

through the linearization of the equations. Both linearized and nonlinear equations of

motions were tested with different control strategies, where the LQR was

implemented on the linearized model and the fuzzy logic controller was designed to

control the nonlinear model of the two-wheeled wheelchair. Upon satisfactory results

of analysis on the virtual prototype and mathematical models with controllers, a full

hardware prototype was developed. The controllers designed were tested

experimentally and it provides promising results where the four-wheeled wheelchair

was able to transform into a two-wheeled wheelchair and stabilized at the upright

position as required.

iii

4

Link1 and Link2

LQRFuzzy logic

controller

.

iv

APPROVAL PAGE

I certify that I have supervised and read this study and that in my opinion it conforms

to acceptable standard of scholarly presentation and is fully adequate, in scope and

quality, as a dissertation for the degree of Master of Science (Mechatronic

Engineering).

……………………………….....

Salmiah Ahmad

Supervisor

………………………………….

Shahrul Na'im Sidek

Co-Supervisor

I certify that I have read this study and that in my opinion it conforms to acceptable

standard of scholarly presentation and is fully adequate, in scope and quality, as a

dissertation for the degree of Master of Science (Mechatronic Engineering).

………………………………….

Md. Raisuddin Khan

Examiner

………………………………….

Amir Akramin Shafie

Examiner

This dissertation was submitted to the Department of Mechatronics Engineering and it

is acceptable as a fulfilment of the requirement for the degree of Master of Science

(Mechatronic Engineering).

……………………………….....

Md. Raisuddin Khan

Head, Department of

Mechatronics Engineering

This dissertation was submitted to the Kulliyyah of Engineering and it is acceptable as

a fulfilment of the requirement for the degree of Master of Science (Mechatronic

Engineering).

………………………………….

Md. Noor Bin Salleh

Dean, Kulliyyah of Engineering

v

DECLARATION

I hereby declare that this dissertation is the result of my own investigation, except

where otherwise stated. I also declare that it has not previously or concurrently

submitted as a whole for any other degree at IIUM or other institutions.

Tareq ALTalmas

Signature……………………………. Date: …………………………

vi

INTERNATIONAL ISLAMIC UNIVERSITY MALAYSIA

COPY RIGHTS PAGE DECLARATION OF COPYRIGHT AND AFFIRMATION OF

FAIR USE OF UNPUBLISHED RESEARCH

Copyright © 2015 by Tareq ALTalmas. All rights reserved.

DESIGN AND DEVELOPMENT OF A NEW STABILIZATION

MECHANISM FOR TWO-WHEELED WHEELCHAIR

No part of this unpublished research may be reproduced, stored in a retrieval

system, or transmitted, in any form or by any means, electronic, mechanical,

photocopying, recording or otherwise without prior written permission of the

copyright holder except as provided below.

i. Any material contained in or derived from this unpublished research

may only be used by others in their writing with due

acknowledgements.

ii. IIUM or its library will have the right to make and transmit copies

(print or electronic) for institutional or academic purposes.

iii. The IIUM will have the right to make, store in a retrieval system and

supply copies of this unpublished research if requested by other

universities and research libraries.

Affirmed by Tareq ALTalmas

……………………..….. ……………….…..

Signature Date

vii

ACKNOWLEDGEMENTS

In the name of Allah, the most Gracious, the most Merciful. Praise be to the Almighty

Allah s.w.t, the God of the universe, for his mercy and blessings that have been

granted to the author. Peace and blessings be upon His messenger Muhammad s.a.w,

his families and companions.

My greatest appreciation and thanks to my project supervisor, Assoc. Professor

Salmiah Ahmed for her precious supervision, guidance as well as help and support

throughout this research. Her invaluable time and energy, idea and knowledge and

patience in guiding me to complete this research are appreciated. Many fields and

aspects have been explored and learned under her supervision.

I would like to dedicate this work to my family. My special thanks for my

father Maher and my mother Sanaa for their Doaa'. Also for my brothers Hossam,

Khalel, Abdullah and Mohammed. And finally for my sister Areej.

I would like to acknowledge the Ministry of Science, Technology and

Innovation (MOSTI) under the e-science fund for funding this project throughout my

study.

viii

TABLE OF CONTENTS

Abstract .................................................................................................................... ii Abstract in Arabic .................................................................................................... iii Approval Page .......................................................................................................... iv Declaration ............................................................................................................... v Copyright Page ......................................................................................................... vi Acknowledgements .................................................................................................. vii List of Tables ........................................................................................................... x List of Figures .......................................................................................................... xi List of Symbols ........................................................................................................ xv

CHAPTER ONE: INTRODUCTION .................................................................. 1 1.1 Introduction and Motivations ................................................................. 1 1.2 Problem Statement ................................................................................. 2 1.3 Aims and Objectives of the Research .................................................... 3 1.4 Methodology .......................................................................................... 4 1.5 Proposed Two-Wheeled Wheelchair ...................................................... 6 1.6 Thesis Outlines ....................................................................................... 7 1.7 Summary ................................................................................................ 8

CHAPTER TWO: LITERATURE REVIEW ..................................................... 9 2.1 Introduction ............................................................................................ 9 2.2 Inverted Pendulum ................................................................................. 10 2.3 Double Inverted Pendulum .................................................................... 12 2.4 Rotary Inverted Pendulum System ......................................................... 14 2.5 Two-Wheeled Mobile Robots ................................................................ 16 2.6 Wheelchair on Two Wheels ................................................................... 22 2.7 Commercial Two-Wheeled Robots ........................................................ 24

CHAPTER THREE: MODELING OF A TWO-WHEELED

WHEELCHAIR ..................................................................................................... 29 3.1 Introduction ............................................................................................ 29 3.2 Modelling of Two-Wheeled Wheelchair Using Solidworks .................. 30

3.2.1 SolidWorks Software .................................................................... 30 3.2.2 Two-Wheeled Wheelchair Virtual Prototyping ............................ 32 3.2.3 3D Full Assembly and Body Specifications ................................. 34 3.2.4 Mates Specifications ..................................................................... 36 3.2.5 Human Weight Representation ..................................................... 37

3.3 Mathematical Modeling of the Two-Wheeled Wheelchair ................... 38 3.3.1 Energy Derivation ......................................................................... 39 3.3.2 Euler-Lagrange Equation of Motion ............................................. 42 3.3.3 State Space Equations ................................................................... 43

3.4 Summary ................................................................................................ 44

CHAPTER FOUR: SIMULATION-BASED PERFORMANCE TESTING ... 46 4.1 Introduction ............................................................................................ 46

ix

4.2 SolidWorks Motion Simulations ............................................................ 46 4.2.1 Turning Diameter and Working Area ........................................... 47 4.2.2 System Behavior without Forces .................................................. 48 4.2.3 Required Torque analysis for Link2 ............................................. 49 4.2.4 Required Torque analysis of wheels' motors ................................ 52 4.2.5 Required Torque analysis from the Main Motors without

Tilting Mechanism ........................................................................ 54 4.2.6 Required torque analysis from the main motors with tilting

mechanism .................................................................................... 55 4.3 Open Loop Poles and System Response for two-wheeled

wheelchair Linear Model ....................................................................... 56 4.4 Control System Requirements for Balancing the System ..................... 57 4.5 System Controllability ........................................................................... 58 4.6 Pole Placement Design ........................................................................... 59 4.7 Linear Quadratic Regulator .................................................................... 61 4.8 Fuzzy Controller Design and Analysis .................................................. 65 4.9 Summary ................................................................................................ 70

CHAPTER FIVE: HARDWARE IMPLEMENTATION AND TEST ............. 71 5.1 Introduction ............................................................................................ 71 5.2 Physical Prototype Description .............................................................. 71 5.3 Drive system ........................................................................................... 73

5.3.1 Motor selection ............................................................................. 74 5.3.2 Brushless DC Motor: .................................................................... 76 5.3.3 Brushed DC Motor (BDC) ............................................................ 77 5.3.4 Motors in the system ..................................................................... 78

5.4 Sensors ................................................................................................... 83 5.4.1 Inertial measurement unit (IMUs) ................................................. 84

5.5 Power system ......................................................................................... 88 5.6 Data Acquisition System (DAQ) ........................................................... 88 5.7 Main motors Analysis ............................................................................ 90 5.8 Experimental analysis of Fuzzy controller ............................................. 91 5.9 Summary ................................................................................................ 94

CHAPTER SIX: CONCLUSION AND RECOMMENDED WORK ............... 96 6.1 Conclusion .............................................................................................. 96 6.2 Contributions .......................................................................................... 97 6.3 Recommendation for further work ......................................................... 98

REFERENCES ....................................................................................................... 99

APPENDIX A PUBLICATIONS ........................................................................ 103 APPENDIX B INPUT AND OUTPUT USER INTERFACE OF SBDM-25A .. 104 APPENDIX C SPECIFICTIONS LIST OF THE BDC MOTOR DRIVER ....... 105 APPENDIX D PINS FUNCTIONS OF FD04A DC MOTOR DRIVER ............ 106 APPENDIX E TRUTH TABLE TO CONTROL THE DIRECTIONS OF

THE MOTORS ............................................................................ 107 APPENDIX F SENSOR SPECIFICATIONS ..................................................... 108 APPENDIX G MODULES THAT ARE USED AND ITS FUNCTIONS .......... 109

x

LIST OF TABLES

Table No. Page No.

4.1 If – then rules for the fuzzy controller (𝑒1, ∆𝑒1, 𝑒2, ∆𝑒2,) 68

5.1 Gains for the Input and output of the Fuzzy logic controller 92

xi

LIST OF FIGURES

Figure No. Page No.

1.1 Research methodology flowchart 5

2.1 Schematic diagram of inverted pendulum system on cart 10

2.2 Inverted pendulum systems on rail. 11

2.3 Schematic diagram of double inverted pendulum system with joint 13

2.4 Rotary inverted pendulums 15

2.5 Two-wheeled mobile robot 16

2.6 New configuration of two-wheeled vehicle with extendable link 19

2.7 Two-wheeled mobile robot for transporting human and good 20

2.8 Two-wheeled inverted pendulum robot 21

2.9 Visual nastran model of the wheelchair with human model 23

2.10 iBOT two-wheeled wheelchair 25

2.11 Segway® personal transporters 26

2.12 Personal urban mobility and accessibility (puma) 27

2.13 Genny two-wheeled wheelchair 27

3.1 Bottom-up assembly design approach flowcharts 31

3.2 The frame of the wheelchair (link1) 32

3.3 Scissor sub assembly (link2) 33

3.4 Caster subassembly 33

3.5 Driving wheel of the wheelchair 34

3.6 Full 3d model of the two-wheeled wheelchair 34

3.7 Occupied length by the wheelchair 35

3.8 Occupied width by the wheelchair 35

3.9 The highest level after raising the scissor lift 36

xii

3.10 The lowest level before raising the scissor lift 36

3.11 The two-wheeled wheelchair with approximated human weight. 38

3.12 Schematic diagram of two-wheeled wheelchair 39

4.1 Turning diameter of two-wheeled wheelchair 47

4.2 Initial situation of the free forces test 48

4.3 Angular displacement of the two-wheeled wheelchair virsus time 48

4.4 Schematic diagram of the link2 49

4.5 Applied motion profile on the motor of the link2 50

4.6 Change of center of mass position of the Link2 51

4.7 Calculated torque based on the Eq. 4.5 51

4.8 Required torque for tilting Link2 from SolidWorks motion

simulation 52

4.9 (a) Wheelchair on four wheels (b) Wheelchair on two wheels 52

4.10 Required torques from the main motors when casters on the ground 53

4.11 Required torques from the main motors when casters is not on the

ground 53

4.12 The initial situation of the wheelchair to calculate the required

torques 54

4.13 Applied profile motion on the motors 54

4.14 Required torques from the motors without using tilting mechanism 55

4.15 Initial condition of the wheelchair with tilting mechanism 56

4.16 Required torques from the main motors after introducing tilting

mechanism 56

4.17 Open loop response for the two-wheeled wheelchair system 57

4.18 Block diagram of pole placement control design 59

4.19 Step response of the two-wheeled system with pole placement 61

4.20 Schematic diagram of the system with lqr 62

4.21 Step response of the two-wheeled system with (LQR) 63

xiii

4.22 Step response of the two-wheeled system after applying lqr with

tuned Q 64

4.23 Block diagram of a PD-like fuzzy control system for link1 and link2 66

4.24 Multi-input single-output balancing of FLC1 66

4.25 Multi-input single-output balancing of FLC2 66

4.26 Membership functions for the inputs error1(𝑒1) and error2 (𝑒2) and

change of error1(∆𝑒1) and change of error2 (∆𝑒2) 67

4.27 Membership functions for the outputs 67

4.28 Control scheme for simulating the nonlinear mathematical model 68

4.29 Angular position of Link1 𝜃1 versus time 69

4.30 Angular position of Link1 𝜃2 versus time 69

5.1 The two-wheeled wheelchair hardware design 72

5.2 Eye- to eye conversation outcome 72

5.3 Brushless dc motor diagram 77

5.4 Two basics design of brushless dc motor 77

5.5 Brushed dc motor diagram 78

5.6 Main motor of the system 79

5.7 Motor for tilting Link2 80

5.8 Warm gear reducer that is attached to the tilting motor 80

5.9 Sbdm-25a brushless dc motor driver 81

5.10 Input and output pins of the driver sbdm-25a 81

5.11 Connection diagrams of the pins 6, 7 and 8 81

5.12 Connection diagram of the speed control 82

5.13 FD04A dc motor driver 82

5.14 Pins orientation of FD04A dc motor driver 83

5.15 SV-IMU5D-LC IMU unit 85

5.16 The measured angle from the gyroscope under static situation 86

xiv

5.17 The measured angle from the gyroscope under rotating situation 86

5.18 The measured angle from accelerometer under static situation 87

5.19 The measured angle from accelerometer under rotating situation 87

5.20 Golden motor battery 88

5.21 The typical pc-based DAQ system 89

5.22 cDAQ-9188 chassis 89

5.23 C-modules that is used as input/output for the controller 90

5.24 Applied voltage on the main motor driver 91

5.25 Feedback from the motor driver in Hz 91

5.26 Block diagram of a pd-like fuzzy control system for link1 and link2 92

5.27 Angular position of Link1, and the angular position error, versus

time 93

5.28 Angular position of link2, and the angular position error, versus time

94

xv

LIST OF SYMBOLS

𝐽𝑅 Moment of Inertia of the Right Wheel

𝐽𝐿 Moment of Inertia of the Left Wheel

𝐾𝑅 Kinetic Energy of the Right Wheel

𝐾𝐿 Kinetic Energy of the Left Wheel

𝐾1 Kinetic Energy of Link1

𝐾2 Kinetic Energy of Link2

𝐾𝑡 Total Kinetic Energy of the System

𝐿1 Length of Link1

𝐿2 Length of Link2

𝑀𝑅 Mass of the Right Wheel

𝑀𝐿 Mass of the Left Wheel

𝑀1 Mass of Link1

𝑀2 Mass of Link2

r Radius of the Wheels

R Angular Displacement of the Right Wheel

𝜃�̇� Angular Velocity of the Right Wheel

R Angular Acceleration of the Right Wheel

L Angular Displacement of the Left Wheel

𝜃�̇� Angular Velocity of the Left Wheel

L Angular Acceleration of the Right Wheel

1 Rotation Angle of Link1

𝜃1̇ Angular Velocity of Link1

xvi

1 Angular Acceleration of Link1

2 Rotation Angle of Link2

𝜃2̇ Angular Velocity of Link2

2 Angular Acceleration of Link2

𝑈𝑅 Potential Energy of the Right Wheel

𝑈𝐿 Potential Energy of the Left Wheel

𝑈1 Potential Energy of Link1

𝑈2 Potential Energy of Link2

𝑈𝑡 Total Potential Energy of the System

x Linear Position of the Wheelchair

𝑋𝑅 , 𝑌𝑅 The Position of the Right Wheel in the x-y Plane

�̇�𝑅 , �̇�𝑅 The Velocity of the Right Wheel in Regard to the x-y Plane

𝑋1, 𝑌1 The Position of the Link1 in the x-y Plane

�̇�1, �̇�1 The Velocity of the Link1 in Regard to the x-y Plane

𝑋2, 𝑌2 The Position of the Link2 in the x-y Plane

�̇�2, �̇�2 The Velocity of the Link2 in Regard to the x-y Plane

1

CHAPTER ONE

INTRODUCTION

1.1 INTRODUCTION AND MOTIVATIONS

Wheelchair is a device used for mobility of the people for whom walking is difficult

or impossible, due to illness or disability. Wheelchairs have many types and versions,

emese rehe wheelchairs are propelled manually (manual wheelchair), while others

move by actuating motors (electric wheelchair).

The population of wheeled mobility device users has increased by 4.3% per

year, and there are about 3.3 million adults using these devices (LaPlante and Kaye,

2010). The use of wheelchair has helped disabled people to be more independent in

their life, which increases the vocational and educational opportunities, reduces

dependence on caregivers and family members, and promotes feelings of self-reliance

(Simpson, 2005). On the other hand, it is very obvious that the user of a normal

wheelchair needs an assistant for their mobility, thus the contributions of those normal

people in the society are affected (Simpson, 2005). There are many types of

wheelchairs that have been designed with special functions. Some of the designs give

the ability to climb over step and curbs (Cooper, et al., 2012), while, others are

derigned te melp ures’r hebility in tme reciety. In pasticular, there was a wheelchair

designed to help user to have face to face conversation with people by lifting the seat

(INDEPENDENCE® iBOT® 4000 Mobility System, 2013). This two-wheeled

wheelchair was invented to give the user the ability to maneuver in confined space.

The lifting mechanism that was designed has the ability of increasing the seat level

2

help the user to act independently, for instance to pick and put things on the shelves in

the library and home.

Disabled and aged people have been using wheelchairs widely for the sake of

mobility since the wheelchairs have become an important assistive tool for them. The

works on invention wheelchairs with extra features have grown rapidly as the industry

of wheelchairs evolve. The field of improving the wheelchair’s features focuses

particularly on tme emeelcmais’r featuser rucm ar derign, tsaveling sange, rtyle, control,

maneuverability, seating, suspension system, and other functions. In fact the

increasing number of wheelchair users with different needs has been motivating the

researches and industry to produce more new designs with extra features.

Two-wheeled wheelchair system is proposed in this research having a unique

function to fulfill the needs among the wheelchair users. The system is designed such

that it has the mechanism of converting its original four-wheeled wheelchair to the

two-wheeled wheelchair with the ability of lifting the seat to give the wheelchair users

more independence during their daily activities and the user may have face-to-face

conversation with other normal people, which indirectly has significant effect on their

emotional and psychology.

1.2 PROBLEM STATEMENT

As mentioned that the number of wheelchair users increases day by day. Therefore,

the need of producing improved products that offer a greater independence and greater

participation in the family and community is also increased. The proposed design will

give the disabled people the desired independence in their daily life.

Nakamura & Murakami, (2009) listed three problems in the structure of the

available four-wheeled wheelchairs. Firstly, the requirement space to turn and move

3

the manual wheelchair needs more space and to make 360 degree turn it need go

forward and backward. Second problem is the resistance of the front wheels. Thirdly,

the seat level which it is not provided face to face conversation with normal people.

(Why Choose Genny, 2012) listed some difficulties for traditional wheelchair users.

Firstly, the casters problem which the users have to take care constantly to prevent it

stuck into little holes or cracks in the pavement. Moreover, the normal wheelchair

users have to keep holding the wheels. The iBOT design has some limitations. It has

the ability to work and balance on two wheels, reach face to face conversation level

and climb stair. But unfortunately, this product is not available currently on the

markets. Genny mobility is another tee emeeled vemicle but it deern’t mave tme ability

to maintain the seat level.

Consequently, the need for two-wheeled mobile vehicle has grown and

attracted many researchers to conduct their researches in this field to come out with

new products that help wheelchair users to be independent as much as possible. These

products have the ability to move and balance on two wheels and maintain the height

of the seat which gives wheelchair users much independence in their daily life.

Therefore, this research on the design and development of a new mechanism of two-

wheeled wheelchair for disabled.

1.3 AIMS AND OBJECTIVES OF THE RESEARCH

The objectives of this research are as follows:

1. To model and develop prototype of a wheelchair system that mimics a

double inverted pendulum scenario.

2. To design a new mechanism for transforming a normal four-wheeled

wheelchair into a two-wheeled wheelchair.

4

3. To design suitable lifting mechanism to increase the height of the seat.

4. To confirm stability of the wheelchair during its motion.

5. To perform hardware implementation of the wheelchair system and

evaluate the performance experimentally.

1.4 METHODOLOGY

To achieve the goal, this research started with conducting reviews and surveys on the

previous designs and works that have been done on the similar issue. Then, different

modeling techniques were used to model the new mechanism for converting a normal

wheelchair on four wheels onto a two-wheeled wheelchair. Then the analyzing stage

taker place emese tme ryrteh’r hecmanirh derigned in tme vistual 3D envisenhent ir

tested. The wheelchair hardware is then realized based on the designed parameters of

the model. Then, the hardware design tested with fuzzy logic controller. This research

intends to help wheelchair users to act independently in their life. Figure 1.1 shows the

research methodology flowchart.

5

Figure 1.1 Research methodology flowchart

6

1.5 PROPOSED TWO-WHEELED WHEELCHAIR

Two-wheeled wheelchair is a complex, highly nonlinear but yet is an interesting and

challenging system to be designed and controlled. It is important to build a proper

design and control strategy to keep this complex system balanced, stable and perform

as similar as normal wheelchair does. Two-wheeled wheelchair is aimed to be suitable

for domestic areas and confined spaces that it will take less space comparing to the

normal four-wheeled wheelchair, particularly during steering process. This is due to

its ability to turn into spot, similar to any mobile robot on two wheels.

This research focuses on developing a new design and mechanism for

transforming normal four-wheeled wheelchair onto a two-wheeled wheelchair by

rising up the front wheels (casters) of the wheelchair. Furthermore, a scissor

mechanism is introduced to change the seat’r height to reach higher level of heights.

This research is aimed to assist the wheelchair users to have independent life. The

encouragements on the proposed wheelchair on two wheels, which mimics a double

inverted pendulum scenario, are:

1. To provide the wheelchair users the ability to maneuverable in confined

spaces such as house, library or offices particularly during the sharp

cornering.

2. To equip the user with the ability to reach higher level of height that will

help them in picking and placing things on shelves and allowing them to

have an eye-to-eye level during conversation with a standing normal

people.

7

1.6 THESIS OUTLINES

The outlines of the thesis are explained as follows;

Chapter One: This chapter introduces and explains the importance of the

wheelchair for disabled and elderly people as a tool for mobility. Then it covers the

problem statement, aims and objectives, methodology, and the proposed design.

Chapter Two: This chapter summarizes a list of previous works that is related

to this research. Inverted pendulum, double inverted pendulum, rotary inverted

pendulum, and then previous researches, and designs have been discussed in this

chapter.

Chapter Three: This chapter discusses a wheelchair 3D model. The process of

3D modelling from part building until full assembly has also been described. This

chapter further presents the mathematical modelling of the proposed two-wheeled

wheelchair system based on Lagrangian approach. Non-linear equations of motion

have been derived then they have been linearized to get the linear state space model.

Chapter Four: This chapter presents the SolidWorks motion simulation, that

simulation has been used to show the turning diameter of the design and system

behavior when raising the casters. It is used also to calculate the required torques from

the Link2 and the effect of using the Link2 in the system. The effects of removing the

casters have also been explained. The open loop step responses of the linear state

space model. Control system requirements have been explained. Moreover, system

controllability has also been tested. The system has been tested with pole placement

approach and linear quadratic regulator (LQR). Further, it is discusses the

implementation of fuzzy logic control on the nonlinear model.

8

Chapter Five: This chapter describes the physical prototype of the two-

wheeled wheelchair system. Then the actuator, power sources and the sensor system

have been discussed as well. In addition, the used data acquisition system and

interfacing has been presented. It is also shows the system behavior after

implementing two independent fuzzy logic controller for each link.

Chapter Six: The conclusions of this work, contribution of research and the

recommendations for further work and improvement have been explained in this

chapter.

1.7 SUMMARY

This chapter has briefly described the introduction and the motivations of the research

of the two-wheeled wheelchair. Then a brief explanation about the proposed design

has been written with the benefits of using two-wheeled wheelchairs system with the

ability ef cmanging tme reat’r meigmt. The aims, objectives, problem statement and

research methodology of the research have been described.