A HEXAPOD ROBOTIC PLATFORM FOR MINIATURE

DRILLING OPERATIONS

BY

MURSHIDUZZAMAN

A thesis submitted in fulfilment of the requirement for the

degree of Master of Science (Mechatronics Engineering)

Kulliyyah of Engineering

International Islamic University Malaysia

MAY 2019

ii

ABSTRACT

Product miniaturization is a key aspect of manufacturing nowadays. Computer

numerically controlled (CNC) machine tools are the major tools used in manufacturing

industries for producing miniaturized products. However, CNC machines are still big,

bulky and stationary. This research is an effort to develop a robot which would be able

to carry out machining operation as a mobile plaform. There have been several

researches going on about the development and application of miniature multi legged

robots. Hexapod robots are small and stable mobile robots which are developed having

a lot of variety. But the main focus of researchers till now have been the structure and

motion of hexapod robots. However, not much research has been conducted about the

use of legged robot for machining application. In this project a Hexapod robot was

designed and fabricated for machining operation. The research scope for this project is

limited to 1-D machining i.e. drilling operation. This research demonstrates

methodically for the first time the feasibility of meso-scale machining using linked

mobile robotic platform. A suitable existing robot (hexapod) design was followed in

this project. A drilling spindle was attached with the robot to carry out the machining

operation. The robot was controlled using serial communication. A Graphical User

Interface (GUI) was developed to control the Hexapod which had all the required

algorithm inside. Machining operations were carried out with the prototype robot to

test its performance. A new compensation algorithm has been proposed to improve the

positional accuracy of the robot movement. The proposed algorithm takes into account

spindle speed and linear velocity to compensate the positional error. The positional

accuracy was improved by 85% after implementing the error compensation scheme. It

was seen that for lowest spindle speed which is 2500RPM and point to point velocity

200mm/min the repeatability was the best which was less than 30µm. The positional

accuracy of the robot movement was compared with that of an existing commercial

micromachining system. The performance of the robot was found to be almost similar

to that of the commercial machine. Finally, the machined hole quality was measured in

terms of circularity and taperness. It was observed that at the best machining parameter

setting, circularity deviation was as low as 0.016 mm and taperness was 0.547 degree.

iii

خلاصة البحث

العددي ت التحكم أدواان تصغير المنتج هو أحد الجوانب الرئيسية للتصنيع في الوقت الحاضر. ان .نتاج المنتجات المصغرة( هي الأدوات الرئيسية المستخدمة في الصناعات التحويلية لإCNCبالكمبيوتر )

ثابتة. هذا البحث هو و الحجم ومع ذلك ، لا تزال آلات التصنيع باستخدام الحاسب الآلي كبيرة وكبيرةاث الجارية حول تطوير هناك العديد من الأبح ،اتفالروبوت من تشغيل الآلي إلى منصة اله جهد لتطوير

، متزنصغير و نقال ت. ان الروبوت سداسي الارجل هو روبو وتطبيق الروبوتات الصغيرة متعددة الأرجلروبوتات اللى بنية وحركة عينصب لحد الان التركيز الرئيسي للباحثين ان. ه لانواع عديدةر يتطو تم الذي و

وت ذو ارجل للتشغيل ، لم يتم إجراء الكثير من الأبحاث حول استخدام روبومع ذلك .سداسية الارجلنطاق البحث لهذا انت. لتشغيل الآلا سداسي الارجلروبوت الهذا المشروع تم تصميم وتصنيع في .الآلي

ان المثال عملية الحفر. ، على سبيلD-1 الاحادي الاتجاه التشغيل عالتي تتبعلى الآلات يقتصر المشروع استخدام ب يستعرض بشكل منهجي ولاول مره جدوى التشغيل متوسط النطاق للالاتالبحث هذا

ابود( في هذا مناسب )هيكسسداسي الارجل تم اتباع تصميم روبوت الوسائل بمنصة هاتف الربوت.ستخدام لتحكم في الروبوت باتم ا .المشروع. تم إرفاق مغزل الحفر مع الروبوت لتنفيذ عملية التشغيل الآلي

داسي الأرجل للتحكم في س (GUI)الاتصال التسلسلي.وقد تم تطوير واجهة المستخدم الرسومية مليات التشغيل مع عوأجريت )هيكسابود( التي كانت تحتوي على جميع الخوارزميات المطلوبة داخلها.

الدقة الموضعية لحركة سين روبوت النموذج الأولي لاختبار أدائها. تم اقتراح خوارزمية تعويض جديدة لتحية لتعويض الخطأ الموضعي. تم تأخذ الخوارزمية المقترحة في الاعتبار سرعة الدوران والسرعة الخط .الروبوت

رعة للمغزل وهي سأدنى لقد وجد بان .٪ بعد تطبيق نظام تعويض الخطأ85تحسين دقة الموضع بنسبة 2500RPM 200و سرعة نقطة إلى نقطةmm / min ل من كرار الأفضل، حيث كان أقكان الت

30µm. يكانيكي التجاري القائم. وتمت مقارنة الدقة الموضعية لحركة الروبوت مع نظام التصنيع الميكرومصنوع قياس جودة الثقب المتمأخيرا اظهرت النتائج ان أداء الروبوت مشابه تقريبا لاداء الجهاز التجاري.و

راف الدئري منخضا كان الانحدوال معالم اعداد أفضل حالة في. لوحظ أنه دائرية والسمك من حيث ال درجة. 0.547 سمك، وكان ال ملم 0.016 الى

iv

APPROVAL PAGE

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

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

quality, as a thesis for the degree of Master of Science (Mechatronics Engineering).

…………………………………..

Tanveer Saleh

Supervisor

…………………………………..

Md. Raisuddin Khan

Co-Supervisor

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

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

for the degree of Master of Science (Mechatronics Engineering).

…………………………………..

Amir Akramin Shafie

Internal Examiner

…………………………………..

Khairul Salleh Mohamed Sahari

External Examiner

This thesis was submitted to the Department of Mechatronics Engineering and is

accepted as a fulfilment of the requirement for the degree of Master of Science

(Mechatronics Engineering).

…………………………………..

Syamsul Bahrin Abdul Hamid

Head, Department of

Mechatronics Engineering

This thesis was submitted to the Kulliyyah of Engineering and is accepted as a

fulfilment of the requirement for the degree of Master of Science (Mechatronics

Engineering).

…………………………………..

Ahmad Faris Ismail

Dean, Kulliyyah of Engineering

v

DECLARATION

I hereby declare that this thesis is the result of my own investigations, except where

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

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

Murshiduzzaman

Signature........................................................... Date.........................................

vi

INTERNATIONAL ISLAMIC UNIVERSITY MALAYSIA

DECLARATION OF COPYRIGHT AND AFFIRMATION OF

FAIR USE OF UNPUBLISHED RESEARCH

A HEXAPOD ROBOT FOR MINIATURE MACHINING

OPERATIONS

I declare that the copyright holders of this thesis are jointly owned by the student

and IIUM.

Copyright © 2019 Murshiduzzaman and International Islamic University Malaysia. All rights

reserved.

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

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

may be used by others in their writing with due acknowledgement.

2. IIUM or its library will have the right to make and transmit copies (print

or electronic) for institutional and academic purposes.

3. The IIUM library will have the right to make, store in a retrieved system

and supply copies of this unpublished research if requested by other

universities and research libraries.

By signing this form, I acknowledged that I have read and understand the IIUM

Intellectual Property Right and Commercialization policy.

Affirmed by Murshiduzzaman

……..…………………….. ………………………..

Signature Date

vii

ACKNOWLEDGEMENTS

Alhumdulillah, all praises to ALLAH (S.W.T), the Most Beneficial and Most Merciful,

to give me the ability and knowledge to accomplish my research work successfully. I

would like to thank my supervisor Dr. Tanveer Saleh for his dedicated guidance,

suggestions, motivation and valuable support which have directed me to develop my

research skills and knowledge. He has not only guided me as a supervisor but also

played the role of a guardian. I would also like to thank my co-supervisor Dr. Md.

Raisuddin Khan for his endless encouragement and support to my research work. I

would like to extend my gratitude to others who also have helped me in using research

instrument for my experiments as the technicians of the Engineering Laboratories in

IIUM.

I am also grateful to Mechatronics Engineering Department and Kulliyyah of

engineering for giving me the research facilities.

Finally, I would like to mention my parents who always keep me in their prayers

to almighty “ALLAH” for every single bit of my success.

viii

TABLE OF CONTENTS

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

List of Symbols ............................................................................................................ xv

List of Abbreviations .................................................................................................. xvi

CHAPTER ONE: INTRODUCTION ........................................................................ 1 1.1 Background ................................................................................................... 1 1.2 Problem Statement And Its Significance ...................................................... 2 1.3 Research Objectives ...................................................................................... 2 1.4 Research Methodology ................................................................................. 3

1.4.1 Methodology For Objective 1 ............................................................. 3 1.4.2 Methodology For Objective 2 ............................................................. 3 1.4.3 Methodology For Objective 3 ............................................................. 4 1.4.4 Methodology For Objective 4 ............................................................. 4

1.5 Research Scope ............................................................................................. 6 1.6 Thesis Organization ...................................................................................... 6

CHAPTER TWO: LITERATURE REVIEW ........................................................... 8 2.1 Introduction................................................................................................... 8 2.2 Hexapod Robots............................................................................................ 9

2.2.1 Comparing Locomotion Of Wheeled, Tracked And Legged

Robots ........................................................................................................ 10 2.2.1.1 Locomotion Using Wheel ...................................................... 11 2.2.1.2 Locomotion Using Tracks ..................................................... 11 2.2.1.3 Locomotion Using Legs ........................................................ 12

2.2.2 Configurations Of Legged Robot ...................................................... 13 2.2.2.1 Stability In Static And Dynamic State ................................... 13 2.2.2.2 Legged Robot’s Walking Speed ............................................ 15 2.2.2.3 Gait Diagrams Of Six Legged Robot .................................... 15

2.2.3 Hexapod Robots Existing Models .................................................... 20 2.3 Machining And Mobile Robots .................................................................. 28 2.4 Hexapod Robot Machines........................................................................... 34 2.5 Chapter Summary ....................................................................................... 36

CHAPTER THREE: DEVELOPMENT OF THE HEXAPOD ROBOT ............. 38 3.1 Introduction................................................................................................. 38 3.2 Hardware System Development ................................................................. 38

3.2.1 Mechanical Structure Of The Hexapod Robot System ..................... 38

ix

3.2.1.1 Body Configuration And Body Design ................................. 40 3.2.1.2 Legs Development Of The Hexapod ..................................... 42 3.2.1.3 Critical Load Calculation For Tibia Leg Link ....................... 45 3.2.1.4 Critical Load Calculation For Femur Leg Link ..................... 46 3.2.1.5 Motor Torque ......................................................................... 47 3.2.1.6 Static Stability........................................................................ 48 3.2.1.7 Machining Spindle ................................................................. 60

3.2.2 Control System Of The Hexapod Robot System .............................. 61 3.2.2.1 Electric Components.............................................................. 62 3.2.2.2 Power Supply ......................................................................... 64

3.3 Development Of The Gui Based Control System ....................................... 65 3.3.1 Gui Of The Hexapod ......................................................................... 70

3.3.1.1 Giving Xy Co-Ordinate For Multiple Point .......................... 73 3.3.1.2 Button Press Command For Hexapod Movement ................. 74 3.3.1.3 Sending Manual Command For Servo Position .................... 74

3.4 Chapter Summary ....................................................................................... 76

CHAPTER FOUR: EXPERIMENTAL SETUP, RESULTS AND

DISCUSSION ............................................................................................................. 77 4.1 Introduction................................................................................................. 77

4.1.1 Materials Preparation For The Experimental Setup .......................... 79 4.1.2 Characterization By Dino-Lite .......................................................... 81 4.1.3 Summary Of Characterization .......................................................... 83

4.2 Results And Discussion .............................................................................. 83 4.3 Positional Accuracy .................................................................................... 83

4.3.1 Benchmarking ................................................................................... 92 4.4 Hole Quality................................................................................................ 93

CHAPTER FIVE: CONCLUSIONS AND RECOMMENDATION .................... 95 5.1 Conclusions................................................................................................. 95 5.2 Recommendations....................................................................................... 96

REFERENCES ........................................................................................................... 97

PUBLICATIONS .................................................................................................... 109

APPENDIX .............................................................................................................. 109

108

x

LIST OF TABLES

Table 4.1 Variable parameters 82

Table 4.2 Average error found by using different parameters along x and y axis

(mm) 84

Table 4.3 Repeatability found by using different parameters (mm) 86

Table 4.4 Error in mm found after moving whole body 91

xi

LIST OF FIGURES

Figure 1.1 Complete Research Flow Chart 5

Figure 2.1 Support pattern used by a multi-legged robot , and the Center of

Mass (CoM) stays inside the support polygon created by the

supporting legs. If the CoM of the Robot stays inside the support

pattern then it is said that Static balancing is occurring. (Siciliano

& Khatib, 2008) 14

Figure 2.2 Two types of configurations which are popular in hexapod robots

16

Figure 2.3 Leg structure of an insect (Shahriari, 2013) 17

Figure 2.4 Leg movement of insects inspired these 4 gaits. Black bars mean

swing phase. Empty area between black bars denote the support

phase. Tripod gait is shown as number 1, Other dynamic gaits

which are seen naturally in the movement of insects like

cockroach (Beer, Quinn, Chiel, & Ritzmann, 1997). 18

Figure 2.5 A faster form of wave gait. Here 4 legs stay is support phase and

2 legs swing to make new footholds (Siciliano & Khatib, 2008).

19

Figure 2.6 Tripod gait. Because of three legs moving at the same time, the

static stability is good (Siciliano & Khatib, 2008). 19

Figure 2.7 Solid model of Robot III (Nelson et al., 1997). 20

Figure 2.8 RHex (Koditschek, Daniel ESaranli & Buehler, 2000) 21

Figure 2.9 Structural design of HITCR-II (Zhang et al., 2014) 22

Figure 2.10 Configuration of HITCR II’s leg (on left) and joint(on right)

(Zhang et al., 2014) 22

Figure 2.11 Wall climbing hexapod robot(on left) and concrete wall surface

& claw(on right) (Funatsu et al., 2014) 23

Figure 2.12 Thrust Mechanism (Funatsu et al., 2014) 23

Figure 2.13 Physical Tigerbug(Left) and Tigerbug in simulation

software(Right) (Sahin & Stevenson, 2015) 24

Figure 2.14 WEBX hexapod design (Webx Hexapod Project, n.d.) 25

xii

Figure 2.15 Round Hexapod(Left) and Rectangular Hexapod(Right) 26

Figure 2.16 Jumping Hexapod (Younse et al., n.d.) 27

Figure 2.17 Pulstech Hexapod (Pulstech, 2009) 28

Figure 2.18 Kiva (D’Andrea, Robot, & 2008, n.d.) 30

Figure 2.19 Timeline from Bogh, et al (Bøgh et al., n.d.) 31

Figure 2.20 Snapshot of simulation video showing drones being used for

palletizing (Amazon.com, 2014) 32

Figure 2.21 Hexapod robotic machining unit, (a) Hexapod platform (b)

Milling spindle attached (Tunc & Shaw, 2016) 34

Figure 2.22 SHeRo hexapod retracted (Left) and expanded (Right) (Agheli

et al., 2014) 345

Figure 2.23 Mobile robotic system for machining (Mobile CNC Base) 346

Figure 3.1 Complete Hexapod 3D design (Left) and Actual (Right)

Hexapod 39

Figure 3.2 Top (Right) and Bottom (Left) body plate [3D Design] 40

Figure 3.3 Top (Left) body plate and flipped view (Right) [Actual] 42

Figure 3.4 3D design of one leg with 3 servo and leg links 43

Figure 3.5 Leg and body links with attached servo horn 44

Figure 3.6 Simplified Structure of the Hexapod 45

Figure 3.7 Simplified Structure of the Hexapod 46

Figure 3.8 Support by 3 legs (robotshop, n.d.) 48

Figure 3.9 Non-perpendicular leg placement (robotshop, n.d.) 48

Figure 3.10 Free body diagram (robotshop, n.d.) 49

Figure 3.11 Stance 1 54

Figure 3.12 Stance 2 55

Figure 3.13 Stance 3 56

Figure 3.14 Stance 4 58

Figure 3.15 Spindle design with scotch yoke mechanism 61

36

35

xiii

Figure 3.16 Lynxmotion SSC-32u servo driver 62

Figure 3.17 12 Ampere Voltage Regulator 63

Figure 3.18 MD10C DC motor driver 63

Figure 3.19 Circuit diagram of the Hexapod robot 64

Figure 3.20 Excel file to calculate required motor rotation using Inverse

Kinematics (Oscarliang.com, n.d.) 66

Figure 3.21 Motor angular movement vs movement of hexapod 67

Figure 3.22 Compensation algorithm 69

Figure 3.23 Graphical User Interface (GUI) of the Hexapod Robot 70

Figure 3.24 Work flow of the GUI 71

Figure 3.25 GUI of the Hexapod robot 72

Figure 3.26 XY co-ordinate for Multiple points 73

Figure 3.27 GUI for CNC machining operation 74

Figure 3.28 Manual Command for Servo Position 75

Figure 3.29 String writing and Sending 75

Figure 4.1 Total experimental procedure 78

Figure 4.2 Levelling of the wooden block using leveler 79

Figure 4.3 Material Placement 80

Figure 4.4 Experimental Setup 81

Figure 4.5 View from Dino-lite 82

Figure 4.6 Graphical representation of average error found by using

different parameters 85

Figure 4.7 Repeatability found by using different parameters in mm 87

Figure 4.8 Graphical representation of repeatability found by using

different parameters 89

Figure 4.9 Graphical representation of average error after using

compensation 90

Figure 4.10 Graphical representation of error between the Hexapod robot

and a CNC machine 91

xiv

Figure 4.11 Error in mm found after moving whole body 92

Figure 4.12 Graphical representation of hole taperness found by using

different parameters 93

Figure 4.13 Graphical representation of standard deviation using different

parameters. 94

xv

LIST OF SYMBOLS

C# C Sharp

E Modulus of Elasticity

I Moment of Inertia

kg Kilo-gram

Kpa Kilo pascal

L1,2,3 Length of link

mm Millimeter

n Number of leg

N1,2 Normal (reaction) force

Pcr Critical Load

T1,2,3,4 Torque acting on joint

V Voltage

W4 Weight of link

3-D Three dimensional

β Duty Factor

σ Bending Stress

µm Micro-meter

ϴ1,2

Angle between leg links

xvi

LIST OF ABBREVIATIONS

CNC Computer Numerically Controlled

CoM Centre of Mass

Coxa Co-Axial

DC Direct Current

DOF Degree Of Freedom

EKF Extended-Kalman-Filter

GUI Graphical User Interface

IC Integrated Circuit

IK Inverse Kinematics

Li-Po Lithium Polymer

MDI Manual Data Input

PCB Printed Circuit Board

R/C Radio Control

RFID Radio Frequency Identification

USB Universal Serial Bus

3D Three Dimensional

1

CHAPTER ONE

INTRODUCTION

1.1 BACKGROUND

A research in 2007 states that ,CNC machine tools have been in use in the manufacturing

sectors for more than 50 years (Thomas, 2007). It is one of the key processes used for

micro fabrication. Recently, demand of micro-fabrication has increased tremendously

due to product miniaturization. CNC machines play a vital role to fabricate mini/micro

parts. CNC machines can work very fast and effectively while the command is given

by some G codes using a computer interface. The computer command controls all the

features of the machining operation like machining speed, feedrate, velocity and so on.

The modern researches about CNC machines usually focus on enhancing the

performance of the CNC machining system. Some researches focus on the delivery of

coolant at the place of machining (Robert Yellin, 2017). There are also a lot of

researches which focus on making the CNC platform capable of doing multiple

operation in the same platform. Some focus on using multiple axis (Gosselin, 2018)

while some other researches focus on incorporating and improving different types of

operations with CNC machining (Tomal et al., 2017).

In this research, a modular hexapod robot was used to carry out machining

operation. Hexapod robots are used in different engineering applications. Many

researchers have investigated kinematic and dynamic behaviour of the hexapods

(Woering, 2011). There are various ways to design the motion patterns of the links of

the hexapod (P. de Santos et al., 2007). Most literatures give wave gait examples of a

2

rectangle shaped robots(Kimura et al., 2006). In the current research, a suitable method

for the walking mechanism of the hexapod was considered based on the literature

review and more focus was given on the development of hexapod assisted micro/mini

machining technology.

1.2 PROBLEM STATEMENT AND ITS SIGNIFICANCE

In different manufacturing processes CNC machining plays an important role. It

provides a very useful way of automatically controlling different machining operations.

However, for miniature product machining (feature size in mm range) conventional

CNC machines are still used with significantly large work envelope. This is inefficient

in terms of space utilization. Generally, CNC machines are bulky and very difficult to

move from one place to another as they are not modular. As such, on site machining is

not possible with current CNC machines.

1.3 RESEARCH OBJECTIVES

This project represents in detail about design and development of a Hexapod machine

capable of machining for new engineering applications. The objectives of the project

are presented below:

1. To develop a Hexapod robot based machining platform for micromachining

operation on large work-piece.

2. To develop a control system for the Hexapod robot for precise machining

operation

3. To design and develop a Graphical User Interface (GUI) for controlling the

motion and machining parameters of the robotic machining platform

4. To evaluate the performance of the robot in terms of machining accuracy

3

1.4 RESEARCH METHODOLOGY

This research was carried out based on experimental design, development and control

implementation of the developed system. The following section describes methodology

for each objective of this proposed project.

1.4.1 Methodology for Objective 1

The mechanical design of the Hexapod was inspired from a previous design which

consists of 6 legs with three degree of freedom in each leg. So, the total degree of

freedom was 3(motor) X 6(legs) =18 DOF (Degrees of Freedom). The design of this

hexapod was inspired from “Phoenix” hexapod of Lynxmotion.com(“Lynxmotion").

This type of structure provided the platform ability to move over the work piece and do

machining operation. There was another servo attached in the front middle area of the

Hexapod which enabled, engage and disengage of the spindle motor. Skotch yoke

mechanism was used to transform the rotary motion of the servo into z axis motion. The

skotch yoke mechanism idea was followed from a CNC hexapod router. But detail

research data were not found (Denton Matt).

1.4.2 Methodology for Objective 2

The whole control system for the Hexapod was developed through using a controller,

circuitry and algorithm. SSC32u servo controller was used to control the position of

servos. To communicate with the servo driver a GUI was developed. Point to point

motion command could be given using the GUI within the workspace of 20mm x 20mm.

The hexapod could do machining while standing at one place locally and also while it

moves with moving its whole body and thus changing its global position.

4

1.4.3 Methodology for Objective 3

For controlling the Hexapod a GUI was developed using C# language. The Hexapod

robot’s various motions was given using the developed GUI. The GUI program helped

to find out the required amount of rotation of each motor to move the Hexapod to an

exact point where the machining is required. The GUI was capable of taking the input

in three ways. Manual data input, button controlled movement and multiple data input

by using text file. A compensation algorithm was adapted to reduce the positional error

of the robotic platform. More about this controlling is discussed in chapter 3.

1.4.4 Methodology for Objective 4

The working ability of the Hexapod was studied. The machining that the Hexapod could

do was checked by standard processes. Different operations was performed with the

Hexapod by varying different parameters of the operation. Its movements was also

checked to ensure that they are good enough and can correctly follow the given

commands. The positional accuracy was measured in terms of distance in mm. The

circularity and taperness was also measured. To find out the taperness, the following

formula was used, 𝜃 = 𝑡𝑎𝑛−1(𝐸𝑛𝑡𝑟𝑦 ℎ𝑜𝑙𝑒 − 𝐸𝑥𝑖𝑡 ℎ𝑜𝑙𝑒 𝑇ℎ𝑖𝑐𝑘𝑛𝑒𝑠𝑠⁄ ). And the hole

circularity is measured by taking diameter from three places of the same hole and then

calculating their standard deviation. If the standard deviation is high, then it means the

hole circularity is less.

5

Figure 1.1 Complete Research Flow Chart

The complete research flow chart is shown in the Fig 1.1 above. From this flow chart,

the steps followed to do this research can be understood.

Development of the mechanical

structure

Development of hardware control

system

Design and development of the

Control System using GUI

Evaluation of the performance of

the system

Does performance

meet the

requirements?

No

Yes

Finish

Start

Use compensation algorithm

Literature review

Benchmarking with standard CNC

machine

Writing Thesis

6

1.5 RESEARCH SCOPE

In most researches, CNC machining and Hexapod robot had been usually two separate

themes. In the research of hexapod robots, machining operations like CNC machining

has not been thought of. Mostly the Hexapod robot research work focus on different

designs, models and movements. In some recent researches, CNC machining is done by

big size Hexapods (Tunc & Shaw, 2016). This mobile hexapod gives certain mobility

and ease of movement of the CNC machining tool. Still the machine is somewhat heavy

and bulky. This research can be thought of as the fusion of mini hexapod robots and

CNC machining. The size of the machine tool was small because of using mini size

Hexapods. Adjusting movement of the robot for rough terrain or obstacle was not

covered in this research.

1.6 THESIS ORGANIZATION

The thesis has been organized in 6 chapters which have highlighted the total research

work in details. The 6 chapters are described briefly as below.

Chapter 1: As described in the previous sections, this chapter provides a brief

product. The last section highlights the research scope of this study technology.

Chapter 2: The literature review starts with introducing different types of

Hexapods and different method of locomotion. Then, different configurations and

walking styles of hexapod robots are discussed. Existing mobile machines and existing

hexapod models are discussed as well.

Chapter 3: The design and development of the whole Hexapod based

machining system is discussed in this chapter. The mechanical development, required

7

stress and torque analysis, electrical components and their application, control

algorithm, GUI instruction all these topics are discussed in this chapter.

Chapter 4: The arrangements required for the experimental procedures are

discussed in this chapter. A wooden block was used as sacrificial material which gave

support and elevated the workpiece. And 3mm Perspex was used to test drilling. Dino-

lite was used for measuring accuracy.

Chapter 5: The data collected from the experiments were shown in this chapter.

Comparison were also shown among use of various parameters.

Chapter 6: The whole work discussed in this thesis is summarized in this

chapter. The shortcomings of this research work is highlighted and recommendations

are also included to give proper direction for future works that will further improve this

hybrid manufacturing system.

8

CHAPTER TWO

LITERATURE REVIEW

2.1 INTRODUCTION

Research about hexapod robots started approximately around late 80’s. Since it is not a

very old research topic, researchers started to create some movement sequences and

structure which can be used effectively as per requirement. Still, there are many research

work going on to optimize the functionality of hexapod robots. At the university of

Duisberg, the department of Mechanics started to develop a hexapod named Tarry I in

1992, which followed the structure of stick insect (Carausius morosus) (Buschmann.,

2000). Later on there were some research work which considered different movement

and structure of hexapod robots. Cockroach like structure was followed in a research in

1997 (Nelson et al., 1997). In the year 2000 some research works were done on a robot

called RHex by Uluq Saranli’, Martin Buehler and Daniel E. Koditschek’ (Koditschek

et al., 2000). In 2012 some work on a hexapod robot called “HITCR II” by Jie Zhao,

He Zhang, Yubin Liu, Jihong Yan, Xizhe Zang and Ziwei Zhou(Zhang et al., 2014) .

This robot was designed in a way so that it was capable of walking on an unstructured

surface. A hexapod robot which was smaller than 9 cm in terms of length, width and

height, was developed by Mayo Funatsu, Yushi Kawasaki, Soichiro Kawasaki and Koki

Kikuchi in 2014. This robot had claws which assisted it to climb concrete wall

(Funatsuat et al, 2014).

The first industrial robot which was commercially available, was made by the

father of industrial grade robotic arm, Joseph Engelberger. He along with his colleagues

designed the first autonomous mobile robots to be used in hospital. Later on there had