Potential Application Of Ferrofluid For Robot Gripping Mechanism.
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
Potential Application of Ferrofluid for
Robot Gripping Mechanism
Thesis submitted in accordance with the requirements of the Universiti Teknikal
Malaysia Melaka for the Bachelor Degree of Manufacturing Engineering
(Robotics and Automation) with Honours
By
Amirul Bin Sait
Faculty of Manufacturing Engineering
May 2008
UTeM Library (Pind.1/2007)
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
BORANG PENGESAHAN STATUS LAPORAN PSM
JUDUL:
POTENTIAL APPLICATION OF FERROFLUID FOR ROBOT GRIPPING MECHANISM
SESI PENGAJIAN: Semester 2 2007/2008
Saya Amirul Bin Sait
mengaku membenarkan laporan PSM / tesis (Sarjana/Doktor Falsafah) ini disimpan
di Perpustakaan Universiti Teknikal Malaysia Melaka (UTeM) dengan syarat-syarat
kegunaan seperti berikut:
1.
2.
3.
4.
Laporan PSM / tesis adalah hak milik Universiti Teknikal Malaysia Melaka dan
penulis.
Perpustakaan Universiti Teknikal Malaysia Melaka dibenarkan membuat salinan
untuk tujuan pengajian sahaja dengan izin penulis.
Perpustakaan dibenarkan membuat salinan laporan PSM / tesis ini sebagai bahan
pertukaran antara institusi pengajian tinggi.
*Sila tandakan (√)
SULIT
(Mengandungi maklumat yang berdarjah keselamatan atau
kepentingan Malaysia yang termaktub di dalam AKTA RAHSIA
RASMI 1972)
TERHAD
(Mengandungi maklumat TERHAD yang telah ditentukan oleh
organisasi/badan di mana penyelidikan dijalankan)
TIDAK TERHAD
(TANDATANGAN PENULIS)
Alamat Tetap:
NO 53 TMN PUTERI, LRG CAHYA
INDAH 1, JLN SULTAN TGH, 93050,
PETRA JAYA, SARAWAK.
(TANDATANGAN PENYELIA)
Cop Rasmi:
Tarikh: _______________________
* Jika
laporan_______________________
PSM ini SULIT atau TERHAD, sila lampirkan surat daripada pihak organisasi berkenaan
Tarikh:
dengan menyatakan sekali sebab dan tempoh tesis ini perlu dikelaskan sebagai SULIT atau TERHAD.
APPROVAL
This report is submitted to the Faculty of Manufacturing Engineering of UTeM as a
partial fulfillment of the requirements for the degree of Bachelor of Manufacturing
Engineering (Robotics and Automation) with Honours. The members of the
supervisory committee are as follow:
Muhamad Arfauz Bin A. Rahman
(PSM Supervisor)
"Insert the date and official stamp here"
DECLARATION
I hereby declare that this report entitled “Potential application of Ferrofluid for
Robot Gripping Mechanism” is the result of my own research except as cited in the
references.
Signature
:
Author’s Name
:
AMIRUL BIN SAIT
Date
:
May 7, 2008
ABSTRACT
Ferrofluids are magnetically controllable fluids where it can be used in positioning
system as an active medium. With an applied external magnetic field, the capability of
the ferrofluid is the main properties for the research. In this study, ferrofluid are used to
develop a potential application in gripping mechanism. The properties and the influences
of the ferrofluid in positioning are gathered and the research start with identify the title
main element which is ferrofluid and the robot gripping mechanism. Through the
literature review, the mechanisms are developed and the development of the robot
gripping mechanism presented in order to come out with a replica. The methodology
consist the method used and explanation related to the robot gripping mechanism
development. Furthermore, the conceptual design presented for design development and
the selection is according to the Pugh screening concept. Then, detail design through the
simulation, replication and analysis process. The simulation output shows how the
mechanism works and gives better understanding about the ferrofluid movement.
Analysis on the force and the moment for the finger and shaft presented according to free
body diagram from the replication. In this case the spring constant or force constant of
the spring determined in order to know the suitable spring force. In addition, the viscosity
of the ferrofluid discussed as it reflect proportionally to the current.
i
ABSTRAK
Ferrofluid adalah cecair magnet yang dapat dimanipulasikan dengan kehadiran suatu
medan magnetik. Dalam kajian ini, cecair magnet digunakan sebagai satu medium
penggerak yang berpotensi dalam mekanisma cengkaman pada robot. Ia dimulakan
dengan menghuraikan isi-isi yang terdapat di dalam tajuk yang melibatkan cecair magnet
dan mekanisma cengkaman robot. Pengumpulan maklumat dilakukan melalui rujukan
jurnal-jurnal, melayari internet serta buku dan setiap maklumat yang berkaitan sahaja
yang diambil. Seterusnya, kaedah-kaedah yang akan digunapakai digariskan dengan
menerangkan proses-proses yang terlibat dalam menghasilkan simulasi dan replika. Oleh
itu, lakaran mekanisma secara dua dimensi dihasilkan untuk setiap idea yang tercetus dan
semua lakaran tersebut akan dipilih menggunakan kaedah matrik Pugh, di mana
rekabentuk yang mendapat markah tertinggi akan dipilih. Berdasarkan rekabentuk
tersebut, lukisan tiga dimensi, simulasi dan replika pula dihasilkan untuk memberi
gambaran yang lebih jelas berkenaan rekabentuk dan mekanisma pergerakan cecair
magnet. Akhir sekali, analisis dibuat ke atas mekanisma tersebut terhadap daya dan
momen yang dihasilkan serta pekali spring dan kelikatan cecair magnet untuk
mendapatkan kesesuaian daya yang diperlukan oleh cecair magnet untuk menggerakkan
aktor.
ii
DEDICATION
For My parents.
iii
ACKNOWLEDGEMENTS
First and foremost, i thanks the almighty god for being my side throughout. I wish to
extend my sincere thanks Mr. Muhamad Arfauz b. A Rahman as my supervisor for
helping and always guiding me throughout the development of the research. I would like
to thank to Mr. Lau Kok Tee, Mr. Ubaidillah, Mr Ahmad Yusairi b. Bani Hashim, Mr
Khairol Anuar b. Rakiman, Mr. Shariman b. Abdullah and Mrs. Silah Hayati bt Kamsani
for providing me with outstanding information to conduct my learning process and
research development. I am grateful to thank my colleagues Mr. Mohd. Azwan b
Mohammad and Mr. Zamri b. Ahmad, as many creative thoughts and valuable discussion
about the research have had a significant influence throughout my project development.
Also not to forget the Faculty of Manufacturing Engineering, Universiti Teknikal
Malaysia Melaka management for allowing me to be a part of the network and thus
giving me a chance to gain useful knowledge and experiences. In addition, i am specially
indebted to Miss Maszilzi Hazeelia bt Mutaza and my parents, Mr Sait Rutu and Mrs
Hatabah Alli for their love, encouragement and support me throughout the development
of this research.
iv
LIST OF FIGURES
2.1
Bar magnet showing line of force between the poles (Myke
8
predko, 2003).
2.2
Rolling bearings with integrated magnetic fluid seals (W.
9
Ochonski, 2005).
2.3
Figure 2.3 : Repulsion of like poles ((Richard J. Fowler, 2003).
10
2.4
Magnetic fields generated by a coil carrying a current (Myke
11
Predko, 2003).
2.5
Example diagram of electromagnet cross-section (Myke Predko,
12
2003).
2.6
Simple application of electromagnet in operation (Myke Predko,
12
2003).
2.7
Composition of magnetic fluids (E. Uhlmann , 2006).
13
2.8
Rolling bearings with integrated magnetic fluid seals (W.
15
Ochonski, 2005).
2.9 (a)
Magnetic field vs. the distance to the magnet magnet (R. Pérez-
17
Castillejos et al, 1999).
2.9 (b)
Mechanical pressure vs. the distance to the magnet (R. Pérez-
18
Castillejos et al, 1999).
2.10
Experimental and theoretically obtained output voltage of the
18
pressure sensor
2.11
Vacuum-rotary feedthrough (W.Ochonski, 2005).
20
2.12
D'Adrsonval galvonometer with ferrofluid (K. Raj et al, 1995).
21
2.13
Tilt sensor utilizing ferrofluid as variable induction core (K. Raj
23
et al, 1995).
2.14
An unusual loudspeaker with dual magnetic gaps and a fiat voice
23
coil (K. Raj et al, 1995).
2.15
Construction of a thick film ferrofluid cell (Luis Martinez et al,
ix
24
2005).
2.16
Optical system for estimation of Verdet constant (Luis Martinez
25
et al, 2005).
2.17
Ferrofluid fixed with a permanent magnet.
26
2.18
Principle and experimental set-up of a one-axis system with
27
scattered (I) and optimized magnetic field (II) (E. Uhlmann & N.
Bayat, 2004)
2.19
Load capacity of the one-axis positioning system for different
28
ferrofluids and volume of fluid.
2.20
Principle and prototype of a miniaturized multidimensional one-
28
axis positioning system.
2.21
Actor cases (at the top) and experimental set-up of multi-axis
29
positioning systems (below at the right) (E. Uhlmann & N.
Bayat, 2004).
3.1 (a)
Flow Chart of the robot gripping mechanism process
32
3.1 (b)
Flow Chart of the robot gripping mechanism process
33
3.2
The step of concept generation method.
34
3.3
Overall “black box”.
36
3.4
Refinement showing subfunctions
37
3.5
Flow chart for the replication of the robot gripper
42
3.6
Influences on the load capacity of the magnetofluidic
43
positioning system (E. Uhlmann & N. Bayat, 2003)
3.7
Influences of the coil current to the actor (E. Uhlmann & N.
45
Bayat, 2003).
4.1
Conceptual design 1
47
4.2
Conceptual design 2
48
4.3
Conceptual design 3
49
4.4
Conceptual design 4
50
4.5
3 Dimensional drawing using Solidworks software
52
4.6
Polygon Cube tool
53
4.7
Channels Object
53
x
4.8
Wireframe of the robot gripper
54
4.9
Shaded modeling diagram
54
4.10
Animation keyframe
55
4.11
Initial position of the designed robot gripper
56
4.12
Gripping position of the robot gripper
57
4.13
Final simulation of the robot gripper
57
4.14
The replication of the robot gripper
60
5.1
The replication cross-sectional diagram
61
5.2
The load versus spring displacement graph.
64
5.3
Load characteristic with the Cobalt Based Ferrofluid (E.
66
Uhlmann & N. Bayat, 2003)
5.4
Connection of the circuit
67
5.5
Electric circuit diagram for the robot gripper mechanism
67
6.1
Friction produce when the actor moves up and down
70
xi
LIST OF TABLES
2.1
Gripper classification according to their physical principle of
operation (Gareth J. Monkman et al, 2007)
2.2
Gripper classification and suitability of object materials (Gareth J.
Monkman et al, 2007)
2.3
7
7
Carriers in the commercial ferrofluid (K. Raj et al, 1995)
16
2.4
Thermal stabilities of successive generations of ferrofluids. Equal
amounts of ferrofluids are exposed to 175°C in dishes until the
fluids congeal. The number of hours represent the relative thermal
stability (K. Raj et al, 1995)
16
2.5
Properties of a thick film ferrofluid cell (Luis Martinez et al, 2005)
25
4.1
The screening matrix for the conceptual design of the robot gripping
mechanism
51
4.2
The manufacturing process involve
58
5.1
Spring displacement when the load applied
63
xii
LIST OF ABBREVIATIONS, SYMBOLS, SPECIALIZED
NOMENCLATURE
nm
-
nanometer
µm
-
micronmeter
2D
-
Two Dimensional
CAD
-
Computer Aided Manufacturing
3D
-
Three Dimensional
xiii
CHAPTER 1
INTRODUCTION
1.1
INTRODUCTION
Materials that are attracted by magnetic fields are called magnetic materials (Robert J.
Fowler, 2003). The most common magnetic materials are iron, iron compound and alloys
containing iron or steel (Robert J. Fowler, 2003). These magnetic materials are also
called ferro magnetic materials as ferro is a prefix that means iron. In general, ferrofluid
is magnetic iron in liquid form. Electricity and magnetism cannot be separated as
magnetism created by an electric current. It is known that an electric current produces a
magnetic field (Robert J. Fowler, 2003). The main application areas which is sealing,
damping and heat transfer, continue to dominate the commercial activities but in each
category new market opportunities have resulted in the development of mechanical
devices and ferrofluids. There is now an increased use of ferrofluids in stepper motors,
and D'Arsonval meters are at the stage of testing. In both cases one of the objectives is to
damp the system and improve product performance. Transducer have become more
importance of the magnetic fluids and, as a result, new sensor products are now in the
manufacturing field.
There has been development in the synthesis of the magnetism and magnetic materials
due to the potential of various applications. As one of the magnetic material, ferrofluid
has been used for biomedical applications and technical applications. In biomedical
applications, it is because by their low toxicity and high magnetizations value for
diagnostics and treatment of tumor cells such as magnetic resonance tomography (MRT),
1
magnetic drug targeting (MDT), magnetic hyperthermia (MHT) and artificial heart and
muscles (Uhlmann, 2006). Biomedical applications focus on the single colloids’
properties. While in technical applications there are more on product and process
application likes loud speaker, lubricants, and seals in feed-through, cooling, sensors and
damping medium (E. Uhlmann, 2006). Technical applications consider the ferrofluids’
properties as a whole fluid described by its magnetorheological behavior, magnetization
and permeability for magnetic forces. In positioning applications, it still less applies.
Magnetic fluid also called ferrofluid (W. Ochonski, 2005), consist magnetic particles that
able to react with magnetic field. Ferro fluids respond immediately to changes in applied
magnetic field and removing the field quickly randomize the moment (W. Ochonski,
2005). It explains that the ferrofluid is compliance and we can manipulate it according to
the wanted current. The magnetic field can be controlled as known magnetic field move
from north to the south. In order to develop the robot gripper, it requires movement and
force. Here, ferrofluid will be used as an active medium for generating a variable
magnetic force which will acts on actor and enables the movement (E. Uhlmann & N.
Bayat, 2004). The magnetic force will be produced from the movement of the ferrofluid
that can be control by the current through the coil installed. Using a permanent magnet
also can produce a magnetic field, however, coil is better as the concentration of the
magnetic field can be manipulate. As a result, it will transmit the force to the actor of the
robot gripper.
There is high potential of ferrofluid applying the robot gripping mechanism as the
ferrofluid inside can be apply to other application, for example, sensoring mechanism.
Also, precise movement can be adjusted through the current applied to the coil.
Furthermore, it is a new technological application of the positioning system instead of
hydraulic, pneumatic and electrical system.
2
1.2
PROBLEM STATEMENT
Using electrical supply is one of the common for developing a robot gripper. However,
the danger of electrical sparks, non-direct drive motors are geared down and can cause
such problems as backlash, friction, compliance and wear which can affect the accuracy
and repeatability of the robot (James W. Masterson et al, 1996).Hydraulics can supply
large amount of instant power and provide precise motion over a wide range of speeds
but it is expensive to purchase and maintain. It is not energy efficient and noisier than
electrical units and due to fluid leaks, they are not recommended for clean room
environments (James W. Masterson et al, 1996).Pneumatics works at high speeds and is
economical to operate and maintain. The disadvantage is air is compressible, making
precise placement and positioning more difficult to control. It is difficult to keep air used
by pneumatic system clean and dry and noisier than either electrical or hydraulic systems
(James W. Masterson et al, 1996). With the use of the ferrofluid, this new technological
application can reduce the noise, as the ferrofluid is reflect only with generated coil.
Besides, the large amount of power can be produce and provide precise motion.
1.3
OBJECTIVE
1.4
To analyze and evaluate the potential application of ferrofluid in robot gripping
mechanism.
To design and develop a replication of a suitable robot gripping mechanism.
SCOPE
To collect, analyze and evaluate the relevant information regarding to the
ferrofluid application from previous and current research.
To design, simulate using Autodesk Maya 8.0 and analyze the robot gripper.
To develop a replication of robot gripper.
3
1.5
BENEFIT
The study on the ferrofluid in robot gripping mechanism will be a new application of
robot gripper instead of using motor, pneumatic and hydraulic. The ferrofluid will be an
active medium to replace the conventional mechanism and it can be exploit for another
usage for example, a sensor as ferrofluid is now widely use. Furthermore, it can reduce
noise, as we know present mechanism that using motor, pneumatic and hydraulic produce
noise. The compliance criteria of the ferrofluid can be manipulate and the relative high
range of positioning with an accuracy of only a few micrometer. In addition, it also can
be use for a safeguard against overload.
4
CHAPTER 2
LITERATURE REVIEW
2.1
ROBOT GRIPPER
Gripper is considered as a subsystem of a handling mechanism which provides temporary
contact with the object to be grasped (Gareth J. Monkman et al, 2007). From the
definition, we can understand that operation of the gripper is grasping an object.
However, the term “gripper” is also used in cases where no actual grasping, but rather
holding an object, for example in vacuum suction where the force can act on a material.
There are many gripper can be found in industry and their functions is depend on the
specific application. According to the Gareth J. Monkman et al, their function can be as
following ;
(a)
Temporary maintenance of a definite position and orientation of the workpiece
relative to the gripper and handling equipment.
(b)
Retaining of static (weight), dynamic (motion, acceleration or deceleration) or
process specific force and moments.
(c)
Determination and change of position and orientation of the object relative to the
handling equipment by means of wrist axes.
(d)
Specific technical operations performed with, or in conjunction with the gripper.
In other word, the main function of a gripper is to grasp and to release workpieces during
the material transfer route (Fan Yu. Chen, 1982). In general, the gripper is a specialized
device that can do specific task or job used to handle one or few objects in a repetitive
operation which required calculated force and versatility.
5
2.2
ROBOT GRIPPER CLASSIFICATION
One should differentiate between grasping (prehension) and holding (retention) forces.
This is important as these are the most used type of gripper in industry. The grasping
force is applied at the initial point of prehension (during the grasping process), while the
holding force maintains the grip thereafter (until object release) (Gareth J. Monkman et
al, 2007). In general, the retention force may be weaker than the prehension force. This is
because the grasping force is determined by the energy required from the mechanical
motion. Robot grippers may be categorized in broadest manner. Fan Yu Chen (1982)
classified gripper into three types which is mechanical finger, vacuum and magnetic, and
universal grippers.
The mechanical finger type is widely used in industry where a direct mechanical force
according to the number of fingers in gripper. The majority of grippers are of the 2-finger
type and 3-finger type of grippers. For vacuum and magnetic type, includes those fitted
with suction cups or electromagnets as force-exerting elements. In other hand, universal
gripper consists of inflatable fingers, soft fingers, 3-fingered grippers and grippers that
are made of mouldable materials (Fan Yu Chen, 1982). The classification by Fan Yu
Chen is based on the function years before 1982. As more new type of gripper has been
develop nowadays, Gareth J. Monkman et al (2007) has classified it more specific based
on the functions, physical of operation and suitability. There are four main groups that
been categorized by Gareth J. Monkman et al (2007) which is : Impactive (a direct
mechanical force from two or mode directions is applied to the object), Ingressive (
prehension of the object is achieved through permeation of the object surface), Astritive
(a binding force is applied in a single direction) and Contigutive (non impactive methods
whereby a direct contact is required to provide a prehension force in a single direction).
These four categories are listed in the table 2.1 and 2.2 below.
6
Table 2.1 : Gripper classification according to their physical principle of operation
(Gareth J. Monkman et al, 2007)
Prehension
method
Gripper type
Impactive
Ingresive
Astrictive
Contigutive
Typical object materials
Rigid objects
Intrusive
Flexible Objects : textiles, carbon and glass fibre
Non-intrusive
Flexible Objects : textiles, carbon and glass fibre
Vacuum suction
Non-porous, rigid materials
Magnetoadhesion
Ferrous materials
Electroadhesion
Light sheet materials and microcomponents
Thermal
Flexible Objects : textiles, carbon and glass fibre
Chemical
Carbon fibre with glue impregnation
Fluid
Small, light objects (microcomponents)
Table 2.2 : Gripper classification and suitability of object materials (Gareth J. Monkman
et al, 2007)
Prehension
method
Impactive
Ingresive
Intrusive
Non-intrusive
Vacuum suction
Typical examples
Clamps (external fingers, internal fingers, chucks,
spring clamps), tongs (parallel, shear, angle,
radial)
Pins, needles, hackles
Hook and loop
Vacuum suction cup/ bellows
Astrictive
Magnetoadhesion
Electroadhesion
Thermal
Chemical
Fluid
Permanent magnet, electromagnet
Electrostatic field
Freezing, melting
Permatack adhesives
Capillary action, surface tension
Contigutive
Gripper type
7
Potential Application of Ferrofluid for
Robot Gripping Mechanism
Thesis submitted in accordance with the requirements of the Universiti Teknikal
Malaysia Melaka for the Bachelor Degree of Manufacturing Engineering
(Robotics and Automation) with Honours
By
Amirul Bin Sait
Faculty of Manufacturing Engineering
May 2008
UTeM Library (Pind.1/2007)
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
BORANG PENGESAHAN STATUS LAPORAN PSM
JUDUL:
POTENTIAL APPLICATION OF FERROFLUID FOR ROBOT GRIPPING MECHANISM
SESI PENGAJIAN: Semester 2 2007/2008
Saya Amirul Bin Sait
mengaku membenarkan laporan PSM / tesis (Sarjana/Doktor Falsafah) ini disimpan
di Perpustakaan Universiti Teknikal Malaysia Melaka (UTeM) dengan syarat-syarat
kegunaan seperti berikut:
1.
2.
3.
4.
Laporan PSM / tesis adalah hak milik Universiti Teknikal Malaysia Melaka dan
penulis.
Perpustakaan Universiti Teknikal Malaysia Melaka dibenarkan membuat salinan
untuk tujuan pengajian sahaja dengan izin penulis.
Perpustakaan dibenarkan membuat salinan laporan PSM / tesis ini sebagai bahan
pertukaran antara institusi pengajian tinggi.
*Sila tandakan (√)
SULIT
(Mengandungi maklumat yang berdarjah keselamatan atau
kepentingan Malaysia yang termaktub di dalam AKTA RAHSIA
RASMI 1972)
TERHAD
(Mengandungi maklumat TERHAD yang telah ditentukan oleh
organisasi/badan di mana penyelidikan dijalankan)
TIDAK TERHAD
(TANDATANGAN PENULIS)
Alamat Tetap:
NO 53 TMN PUTERI, LRG CAHYA
INDAH 1, JLN SULTAN TGH, 93050,
PETRA JAYA, SARAWAK.
(TANDATANGAN PENYELIA)
Cop Rasmi:
Tarikh: _______________________
* Jika
laporan_______________________
PSM ini SULIT atau TERHAD, sila lampirkan surat daripada pihak organisasi berkenaan
Tarikh:
dengan menyatakan sekali sebab dan tempoh tesis ini perlu dikelaskan sebagai SULIT atau TERHAD.
APPROVAL
This report is submitted to the Faculty of Manufacturing Engineering of UTeM as a
partial fulfillment of the requirements for the degree of Bachelor of Manufacturing
Engineering (Robotics and Automation) with Honours. The members of the
supervisory committee are as follow:
Muhamad Arfauz Bin A. Rahman
(PSM Supervisor)
"Insert the date and official stamp here"
DECLARATION
I hereby declare that this report entitled “Potential application of Ferrofluid for
Robot Gripping Mechanism” is the result of my own research except as cited in the
references.
Signature
:
Author’s Name
:
AMIRUL BIN SAIT
Date
:
May 7, 2008
ABSTRACT
Ferrofluids are magnetically controllable fluids where it can be used in positioning
system as an active medium. With an applied external magnetic field, the capability of
the ferrofluid is the main properties for the research. In this study, ferrofluid are used to
develop a potential application in gripping mechanism. The properties and the influences
of the ferrofluid in positioning are gathered and the research start with identify the title
main element which is ferrofluid and the robot gripping mechanism. Through the
literature review, the mechanisms are developed and the development of the robot
gripping mechanism presented in order to come out with a replica. The methodology
consist the method used and explanation related to the robot gripping mechanism
development. Furthermore, the conceptual design presented for design development and
the selection is according to the Pugh screening concept. Then, detail design through the
simulation, replication and analysis process. The simulation output shows how the
mechanism works and gives better understanding about the ferrofluid movement.
Analysis on the force and the moment for the finger and shaft presented according to free
body diagram from the replication. In this case the spring constant or force constant of
the spring determined in order to know the suitable spring force. In addition, the viscosity
of the ferrofluid discussed as it reflect proportionally to the current.
i
ABSTRAK
Ferrofluid adalah cecair magnet yang dapat dimanipulasikan dengan kehadiran suatu
medan magnetik. Dalam kajian ini, cecair magnet digunakan sebagai satu medium
penggerak yang berpotensi dalam mekanisma cengkaman pada robot. Ia dimulakan
dengan menghuraikan isi-isi yang terdapat di dalam tajuk yang melibatkan cecair magnet
dan mekanisma cengkaman robot. Pengumpulan maklumat dilakukan melalui rujukan
jurnal-jurnal, melayari internet serta buku dan setiap maklumat yang berkaitan sahaja
yang diambil. Seterusnya, kaedah-kaedah yang akan digunapakai digariskan dengan
menerangkan proses-proses yang terlibat dalam menghasilkan simulasi dan replika. Oleh
itu, lakaran mekanisma secara dua dimensi dihasilkan untuk setiap idea yang tercetus dan
semua lakaran tersebut akan dipilih menggunakan kaedah matrik Pugh, di mana
rekabentuk yang mendapat markah tertinggi akan dipilih. Berdasarkan rekabentuk
tersebut, lukisan tiga dimensi, simulasi dan replika pula dihasilkan untuk memberi
gambaran yang lebih jelas berkenaan rekabentuk dan mekanisma pergerakan cecair
magnet. Akhir sekali, analisis dibuat ke atas mekanisma tersebut terhadap daya dan
momen yang dihasilkan serta pekali spring dan kelikatan cecair magnet untuk
mendapatkan kesesuaian daya yang diperlukan oleh cecair magnet untuk menggerakkan
aktor.
ii
DEDICATION
For My parents.
iii
ACKNOWLEDGEMENTS
First and foremost, i thanks the almighty god for being my side throughout. I wish to
extend my sincere thanks Mr. Muhamad Arfauz b. A Rahman as my supervisor for
helping and always guiding me throughout the development of the research. I would like
to thank to Mr. Lau Kok Tee, Mr. Ubaidillah, Mr Ahmad Yusairi b. Bani Hashim, Mr
Khairol Anuar b. Rakiman, Mr. Shariman b. Abdullah and Mrs. Silah Hayati bt Kamsani
for providing me with outstanding information to conduct my learning process and
research development. I am grateful to thank my colleagues Mr. Mohd. Azwan b
Mohammad and Mr. Zamri b. Ahmad, as many creative thoughts and valuable discussion
about the research have had a significant influence throughout my project development.
Also not to forget the Faculty of Manufacturing Engineering, Universiti Teknikal
Malaysia Melaka management for allowing me to be a part of the network and thus
giving me a chance to gain useful knowledge and experiences. In addition, i am specially
indebted to Miss Maszilzi Hazeelia bt Mutaza and my parents, Mr Sait Rutu and Mrs
Hatabah Alli for their love, encouragement and support me throughout the development
of this research.
iv
LIST OF FIGURES
2.1
Bar magnet showing line of force between the poles (Myke
8
predko, 2003).
2.2
Rolling bearings with integrated magnetic fluid seals (W.
9
Ochonski, 2005).
2.3
Figure 2.3 : Repulsion of like poles ((Richard J. Fowler, 2003).
10
2.4
Magnetic fields generated by a coil carrying a current (Myke
11
Predko, 2003).
2.5
Example diagram of electromagnet cross-section (Myke Predko,
12
2003).
2.6
Simple application of electromagnet in operation (Myke Predko,
12
2003).
2.7
Composition of magnetic fluids (E. Uhlmann , 2006).
13
2.8
Rolling bearings with integrated magnetic fluid seals (W.
15
Ochonski, 2005).
2.9 (a)
Magnetic field vs. the distance to the magnet magnet (R. Pérez-
17
Castillejos et al, 1999).
2.9 (b)
Mechanical pressure vs. the distance to the magnet (R. Pérez-
18
Castillejos et al, 1999).
2.10
Experimental and theoretically obtained output voltage of the
18
pressure sensor
2.11
Vacuum-rotary feedthrough (W.Ochonski, 2005).
20
2.12
D'Adrsonval galvonometer with ferrofluid (K. Raj et al, 1995).
21
2.13
Tilt sensor utilizing ferrofluid as variable induction core (K. Raj
23
et al, 1995).
2.14
An unusual loudspeaker with dual magnetic gaps and a fiat voice
23
coil (K. Raj et al, 1995).
2.15
Construction of a thick film ferrofluid cell (Luis Martinez et al,
ix
24
2005).
2.16
Optical system for estimation of Verdet constant (Luis Martinez
25
et al, 2005).
2.17
Ferrofluid fixed with a permanent magnet.
26
2.18
Principle and experimental set-up of a one-axis system with
27
scattered (I) and optimized magnetic field (II) (E. Uhlmann & N.
Bayat, 2004)
2.19
Load capacity of the one-axis positioning system for different
28
ferrofluids and volume of fluid.
2.20
Principle and prototype of a miniaturized multidimensional one-
28
axis positioning system.
2.21
Actor cases (at the top) and experimental set-up of multi-axis
29
positioning systems (below at the right) (E. Uhlmann & N.
Bayat, 2004).
3.1 (a)
Flow Chart of the robot gripping mechanism process
32
3.1 (b)
Flow Chart of the robot gripping mechanism process
33
3.2
The step of concept generation method.
34
3.3
Overall “black box”.
36
3.4
Refinement showing subfunctions
37
3.5
Flow chart for the replication of the robot gripper
42
3.6
Influences on the load capacity of the magnetofluidic
43
positioning system (E. Uhlmann & N. Bayat, 2003)
3.7
Influences of the coil current to the actor (E. Uhlmann & N.
45
Bayat, 2003).
4.1
Conceptual design 1
47
4.2
Conceptual design 2
48
4.3
Conceptual design 3
49
4.4
Conceptual design 4
50
4.5
3 Dimensional drawing using Solidworks software
52
4.6
Polygon Cube tool
53
4.7
Channels Object
53
x
4.8
Wireframe of the robot gripper
54
4.9
Shaded modeling diagram
54
4.10
Animation keyframe
55
4.11
Initial position of the designed robot gripper
56
4.12
Gripping position of the robot gripper
57
4.13
Final simulation of the robot gripper
57
4.14
The replication of the robot gripper
60
5.1
The replication cross-sectional diagram
61
5.2
The load versus spring displacement graph.
64
5.3
Load characteristic with the Cobalt Based Ferrofluid (E.
66
Uhlmann & N. Bayat, 2003)
5.4
Connection of the circuit
67
5.5
Electric circuit diagram for the robot gripper mechanism
67
6.1
Friction produce when the actor moves up and down
70
xi
LIST OF TABLES
2.1
Gripper classification according to their physical principle of
operation (Gareth J. Monkman et al, 2007)
2.2
Gripper classification and suitability of object materials (Gareth J.
Monkman et al, 2007)
2.3
7
7
Carriers in the commercial ferrofluid (K. Raj et al, 1995)
16
2.4
Thermal stabilities of successive generations of ferrofluids. Equal
amounts of ferrofluids are exposed to 175°C in dishes until the
fluids congeal. The number of hours represent the relative thermal
stability (K. Raj et al, 1995)
16
2.5
Properties of a thick film ferrofluid cell (Luis Martinez et al, 2005)
25
4.1
The screening matrix for the conceptual design of the robot gripping
mechanism
51
4.2
The manufacturing process involve
58
5.1
Spring displacement when the load applied
63
xii
LIST OF ABBREVIATIONS, SYMBOLS, SPECIALIZED
NOMENCLATURE
nm
-
nanometer
µm
-
micronmeter
2D
-
Two Dimensional
CAD
-
Computer Aided Manufacturing
3D
-
Three Dimensional
xiii
CHAPTER 1
INTRODUCTION
1.1
INTRODUCTION
Materials that are attracted by magnetic fields are called magnetic materials (Robert J.
Fowler, 2003). The most common magnetic materials are iron, iron compound and alloys
containing iron or steel (Robert J. Fowler, 2003). These magnetic materials are also
called ferro magnetic materials as ferro is a prefix that means iron. In general, ferrofluid
is magnetic iron in liquid form. Electricity and magnetism cannot be separated as
magnetism created by an electric current. It is known that an electric current produces a
magnetic field (Robert J. Fowler, 2003). The main application areas which is sealing,
damping and heat transfer, continue to dominate the commercial activities but in each
category new market opportunities have resulted in the development of mechanical
devices and ferrofluids. There is now an increased use of ferrofluids in stepper motors,
and D'Arsonval meters are at the stage of testing. In both cases one of the objectives is to
damp the system and improve product performance. Transducer have become more
importance of the magnetic fluids and, as a result, new sensor products are now in the
manufacturing field.
There has been development in the synthesis of the magnetism and magnetic materials
due to the potential of various applications. As one of the magnetic material, ferrofluid
has been used for biomedical applications and technical applications. In biomedical
applications, it is because by their low toxicity and high magnetizations value for
diagnostics and treatment of tumor cells such as magnetic resonance tomography (MRT),
1
magnetic drug targeting (MDT), magnetic hyperthermia (MHT) and artificial heart and
muscles (Uhlmann, 2006). Biomedical applications focus on the single colloids’
properties. While in technical applications there are more on product and process
application likes loud speaker, lubricants, and seals in feed-through, cooling, sensors and
damping medium (E. Uhlmann, 2006). Technical applications consider the ferrofluids’
properties as a whole fluid described by its magnetorheological behavior, magnetization
and permeability for magnetic forces. In positioning applications, it still less applies.
Magnetic fluid also called ferrofluid (W. Ochonski, 2005), consist magnetic particles that
able to react with magnetic field. Ferro fluids respond immediately to changes in applied
magnetic field and removing the field quickly randomize the moment (W. Ochonski,
2005). It explains that the ferrofluid is compliance and we can manipulate it according to
the wanted current. The magnetic field can be controlled as known magnetic field move
from north to the south. In order to develop the robot gripper, it requires movement and
force. Here, ferrofluid will be used as an active medium for generating a variable
magnetic force which will acts on actor and enables the movement (E. Uhlmann & N.
Bayat, 2004). The magnetic force will be produced from the movement of the ferrofluid
that can be control by the current through the coil installed. Using a permanent magnet
also can produce a magnetic field, however, coil is better as the concentration of the
magnetic field can be manipulate. As a result, it will transmit the force to the actor of the
robot gripper.
There is high potential of ferrofluid applying the robot gripping mechanism as the
ferrofluid inside can be apply to other application, for example, sensoring mechanism.
Also, precise movement can be adjusted through the current applied to the coil.
Furthermore, it is a new technological application of the positioning system instead of
hydraulic, pneumatic and electrical system.
2
1.2
PROBLEM STATEMENT
Using electrical supply is one of the common for developing a robot gripper. However,
the danger of electrical sparks, non-direct drive motors are geared down and can cause
such problems as backlash, friction, compliance and wear which can affect the accuracy
and repeatability of the robot (James W. Masterson et al, 1996).Hydraulics can supply
large amount of instant power and provide precise motion over a wide range of speeds
but it is expensive to purchase and maintain. It is not energy efficient and noisier than
electrical units and due to fluid leaks, they are not recommended for clean room
environments (James W. Masterson et al, 1996).Pneumatics works at high speeds and is
economical to operate and maintain. The disadvantage is air is compressible, making
precise placement and positioning more difficult to control. It is difficult to keep air used
by pneumatic system clean and dry and noisier than either electrical or hydraulic systems
(James W. Masterson et al, 1996). With the use of the ferrofluid, this new technological
application can reduce the noise, as the ferrofluid is reflect only with generated coil.
Besides, the large amount of power can be produce and provide precise motion.
1.3
OBJECTIVE
1.4
To analyze and evaluate the potential application of ferrofluid in robot gripping
mechanism.
To design and develop a replication of a suitable robot gripping mechanism.
SCOPE
To collect, analyze and evaluate the relevant information regarding to the
ferrofluid application from previous and current research.
To design, simulate using Autodesk Maya 8.0 and analyze the robot gripper.
To develop a replication of robot gripper.
3
1.5
BENEFIT
The study on the ferrofluid in robot gripping mechanism will be a new application of
robot gripper instead of using motor, pneumatic and hydraulic. The ferrofluid will be an
active medium to replace the conventional mechanism and it can be exploit for another
usage for example, a sensor as ferrofluid is now widely use. Furthermore, it can reduce
noise, as we know present mechanism that using motor, pneumatic and hydraulic produce
noise. The compliance criteria of the ferrofluid can be manipulate and the relative high
range of positioning with an accuracy of only a few micrometer. In addition, it also can
be use for a safeguard against overload.
4
CHAPTER 2
LITERATURE REVIEW
2.1
ROBOT GRIPPER
Gripper is considered as a subsystem of a handling mechanism which provides temporary
contact with the object to be grasped (Gareth J. Monkman et al, 2007). From the
definition, we can understand that operation of the gripper is grasping an object.
However, the term “gripper” is also used in cases where no actual grasping, but rather
holding an object, for example in vacuum suction where the force can act on a material.
There are many gripper can be found in industry and their functions is depend on the
specific application. According to the Gareth J. Monkman et al, their function can be as
following ;
(a)
Temporary maintenance of a definite position and orientation of the workpiece
relative to the gripper and handling equipment.
(b)
Retaining of static (weight), dynamic (motion, acceleration or deceleration) or
process specific force and moments.
(c)
Determination and change of position and orientation of the object relative to the
handling equipment by means of wrist axes.
(d)
Specific technical operations performed with, or in conjunction with the gripper.
In other word, the main function of a gripper is to grasp and to release workpieces during
the material transfer route (Fan Yu. Chen, 1982). In general, the gripper is a specialized
device that can do specific task or job used to handle one or few objects in a repetitive
operation which required calculated force and versatility.
5
2.2
ROBOT GRIPPER CLASSIFICATION
One should differentiate between grasping (prehension) and holding (retention) forces.
This is important as these are the most used type of gripper in industry. The grasping
force is applied at the initial point of prehension (during the grasping process), while the
holding force maintains the grip thereafter (until object release) (Gareth J. Monkman et
al, 2007). In general, the retention force may be weaker than the prehension force. This is
because the grasping force is determined by the energy required from the mechanical
motion. Robot grippers may be categorized in broadest manner. Fan Yu Chen (1982)
classified gripper into three types which is mechanical finger, vacuum and magnetic, and
universal grippers.
The mechanical finger type is widely used in industry where a direct mechanical force
according to the number of fingers in gripper. The majority of grippers are of the 2-finger
type and 3-finger type of grippers. For vacuum and magnetic type, includes those fitted
with suction cups or electromagnets as force-exerting elements. In other hand, universal
gripper consists of inflatable fingers, soft fingers, 3-fingered grippers and grippers that
are made of mouldable materials (Fan Yu Chen, 1982). The classification by Fan Yu
Chen is based on the function years before 1982. As more new type of gripper has been
develop nowadays, Gareth J. Monkman et al (2007) has classified it more specific based
on the functions, physical of operation and suitability. There are four main groups that
been categorized by Gareth J. Monkman et al (2007) which is : Impactive (a direct
mechanical force from two or mode directions is applied to the object), Ingressive (
prehension of the object is achieved through permeation of the object surface), Astritive
(a binding force is applied in a single direction) and Contigutive (non impactive methods
whereby a direct contact is required to provide a prehension force in a single direction).
These four categories are listed in the table 2.1 and 2.2 below.
6
Table 2.1 : Gripper classification according to their physical principle of operation
(Gareth J. Monkman et al, 2007)
Prehension
method
Gripper type
Impactive
Ingresive
Astrictive
Contigutive
Typical object materials
Rigid objects
Intrusive
Flexible Objects : textiles, carbon and glass fibre
Non-intrusive
Flexible Objects : textiles, carbon and glass fibre
Vacuum suction
Non-porous, rigid materials
Magnetoadhesion
Ferrous materials
Electroadhesion
Light sheet materials and microcomponents
Thermal
Flexible Objects : textiles, carbon and glass fibre
Chemical
Carbon fibre with glue impregnation
Fluid
Small, light objects (microcomponents)
Table 2.2 : Gripper classification and suitability of object materials (Gareth J. Monkman
et al, 2007)
Prehension
method
Impactive
Ingresive
Intrusive
Non-intrusive
Vacuum suction
Typical examples
Clamps (external fingers, internal fingers, chucks,
spring clamps), tongs (parallel, shear, angle,
radial)
Pins, needles, hackles
Hook and loop
Vacuum suction cup/ bellows
Astrictive
Magnetoadhesion
Electroadhesion
Thermal
Chemical
Fluid
Permanent magnet, electromagnet
Electrostatic field
Freezing, melting
Permatack adhesives
Capillary action, surface tension
Contigutive
Gripper type
7