UNIVERSITI TEKNIKAL MALAYSIA MELAKA

MECHANISM DEVELPOMENT OF GRIPPER FOR 5KG

PAYLOAD

This report submitted in accordance with requirement of the Universiti Teknikal

Malaysia Melaka (UTeM) for the Bachelor Degree of Manufacturing Engineering

(Robotic and Automation) with Honours.

by

MOHD JUZAILI @ AHMAD SYAIHAN BIN LOKMAN

FACULTY OF MANUFACTURING ENGINEERING

2010

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

BORANG PENGESAHAN STATUS LAPORAN PSM

JUDUL: MECHANISM DEVELOPMENT OF GRIPPER FOR 5 KG PAYLOAD

SESI PENGAJIAN: 2009-2010

Saya MOHD JUZAILI @ AHMAD SYAIHAN BIN LOKMAN mengaku membenarkan tesis (PSM/Sarjana/Doktor Falsafah) ini disimpan di Perpustakaan Universiti Teknikal Malaysia Melaka (UTeM) dengan syarat-syarat kegunaan seperti berikut:

1. Tesis adalah hak milik Universiti Teknikal Malaysia Melaka . 2. Perpustakaan Universiti Teknikal Malaysia Melaka dibenarkan membuat salinan

untuk tujuan pengajian sahaja. 3. Perpustakaan dibenarkan membuat salinan tesis ini sebagai bahan pertukaran

antara institusi pengajian tinggi.

4. **Sila tandakan (√)

SULIT

TERHAD

TIDAK TERHAD

(Mengandungi maklumat yang berdarjah keselamatan atau kepentingan Malaysia yang termaktub di dalam

AKTA RAHSIA RASMI 1972)

(Mengandungi maklumat TERHAD yang telah ditentukan

oleh organisasi/badan di mana penyelidikan dijalankan)

(MOHD JUZAILI @ AHMAD SYAIHAN

BIN LOKMAN) Alamat Tetap: NO 11, KG SIMPANG 4

35900, TG MALIM

PERAK

Tarikh: _______________________

Disahkan oleh:

(EN KHAIROL ANUAR BIN RAKIMAN)

Cop Rasmi:

Tarikh: _______________________

* Jika laporan PSM ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi berkenaan dengan menyatakan sekali sebab dan tempoh tesis ini perlu dikelaskan sebagai SULIT atau TERHAD.

DECLARATION

I hereby declare that this report entitled “Mechanism Development of Gripper for 5Kg

payload” is the result of my own research except as cited in the references.

Signature :

Author’s Name : Mohd Juzaili @ Ahmad Syaihan Bin Lokman

Date :

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 (Robotic and Automation). The members of the supervisory committee are

as follow:

Supervisor

En Khairol Anuar Bin Rakiman

Faculty of Manufacturing Engineering

i

ABSTRAK

Projek ini adalah berkaitan mekanisma dan pembangunan pencengkam dengan

muatan 5kg. Penghasilan pencengkam memerlukan beberapa kajian dan analisis

rekaan-rekaan yang telah wujud seperti penggunaan bahan, proses pembuatan dan

sebagainya. Projek terdahulu telah dibuat dari segi reka bentuk dan analisa berkenaan

pencengkam. Dalam projek ini, ia lebi fokus kepada proses yang terlibat di dalam

pembangunan pencengkam proses seperti memilih proses bahan, proses yang terlibat

dan proses pemasangan yang digunakan dalam penghasilan pencengkam. Komponen

pencengkam yang dihasilkan digabungkan sehingga sebuah pencengkam yang

lengkap dihasilkan. Kemudian ujian terhadap fungsi dan keupayaan pencengkam

telah dibuat untuk memastikan pencengkam dapat bertahan dan berfungsi

sepenuhnya.

ii

ABSTRACT

This project is about on mechanism and development of gripper with 5kg payload.

Gripper production need some study and analysis already existing designs such as

material utilisation, manufacturing process etc. In chapter 1, it covering about

introduction, project objective and scope the. Formerly, projects were made early in

gripper design and analyzing about the gripper structures and functionability. In this

project, its focusing on involved process research in gripper development process

like material selection process, involved process and assembly process applies in

gripper development. The gripper component is begin with fabrication of gripper

mechanism following with the gripper assembly until the complete gripper was

developed. Then the testing of gripper function and ability has been made to make

sure the gripper is sustained and fully functional.

iii

DEDICATION

To my beloved family and friends.

iv

ACKNOWLEDGEMENT

There are many people who deserve thanks for the contributions they have made to

this project. Firstly, I would like to express my endless grateful to my Final Year

Project’s Principal Supervisor, Encik Khairol Anuar Bin Rakiman. He directed and

instructed me through every phase of the project, and his guidance has been

invaluable. He also spent time and effort helping to resolve new issue by giving

advice and suggestion as the project developed and checking the report a number of

times.

I would like to thank my beloved parent, for their abiding love and endless patience.

Their support has been constant and enduring through the process of this project.

They deserve an enormous amount of recognition for their moral support throughout

this project. I am also grateful for all of my friends, who had giving their help and

idea in completing this project. Finally, I am deeply indebted to the lab technician

and all of the people that had directly or indirectly helped me during the period of

completing the project. Thank you.

v

TABLE OF CONTENTS

Abstrak i

Abstract ii

Dedication iii

Acknowledgement iv

Table of Content v

List of Figure ix

List of Table xi

1. INTRODUCTION 1

1.1 Overview 1

1.2 Problem Statement 3

1.3 Objectives of the project 4

1.4 Scope of Project 4

2. LITERATURE REVIEW 5

2.1 Overview 5

2.1.1 Operation 7

2.2 Gripping Action 7

2.2.1 External Gripping 7

2.2.2 Internal Gripping 7

2.3 Type of gripper 8

2.4 Existing Gripper Analysis 8

2.4.1 Major Factors in Choosing a Gripper and Jaw Design 8

2.4.2 Tolerance Analysis 10

2.4.2.1 Tolerance Analysis of Mechanisms 12

2.4.2.2 Tolerance Type 13

2.5 Major Factor Considerations in Manufacturing Gripper 14

2.5.1 Material Selection 14

2.5.1.1 Overview 14

2.5.1.2 Cost Issues 15

vi

2.5.1.3 Material Category 16

a) Plastics 16

i) High Density PolyEthylene (HDPE) 16

ii) PolyTetraFluorEtylene (PTFE) 17

iii) Neoprene 18

b) Metals 19

i) Aluminum 19

ii) Stainless Steel 20

iii) Mild Steel 21

c) Carbon Fiber 22

2.5.1.4 Material comparison 23

2.5.2 Manufacturing Process Selection 25

2.5.2.1 Fabrication of Gripper 25

2.5.2.2 Laser Cutting Machining (LCM) 25

2.5.2.3 Electrical Discharge Machining (EDM) 27

2.5.2.4 Turning Process 27

2.5.2.5 Milling 29

2.5.2.6 Grinding 30

2.5.2.7 Drilling 30

2.5.2.8 Fuse Deposition Modelling(FDM) 31

2.5.3 Gripper Assembly 32

2.5.3.1 Fastener 32

a) Bolt and machine Screw 32

b) Thread type Classification 33

i) Tapping Screw 32

ii) Slotted Screw 33

iii) Socket Head Cap Screw 34

c) Material Description of Screw 34

2.6 Gripper testing 34

2.6.1 Physical Prototype Testing 35

2.7 Conclusion 36

vii

3. METHODOLOGY 37

3.1 Introduction 37

3.2 Project Planning 37

3.3 Detail planning 39

3.4 Study of Preliminary Design 39

3.5 Finalize Conceptual Design Prototype 40

3.6 Protoype Fabrication Process 40

3.7 Assembly Process 43

3.8 Prototype Functional Testing 43

4. GRIPPER FABRICATION PROCESS 44

4.1 Introduction 44

4.2 Material Selection 44

4.3 Bill of material 45

4.4 Fabrication Process 47

4.4.1 Flow Chart Overview 49

4.4.2 Part 1: Base Fabrication 51

4.4.3 Part 2: Link/Supporter Fabrication 53

4.4.4 Part 3: Jaw Fabrication 56

4.5 Assembly Process 58

4.5.1 Gripper Assembly 58

4.5.2 Mechanical Component 60

5. GRIPPER FUNCTIONAL TESTING 62

5.1 Overview 62

5.2 Result 62

5.3 Griper Feature 64

5.3.1 Stability 64

5.3.2 Low Cost 65

5.3.3 Minimum Gripper Weight 65

5.3.4 Flexibility 66

5.3.5 Easy of Assembly or Disassembly 66

viii

5.4 Testing 67

5.4.1 Ability of gripper to extend and retract 67

5.4.2 Gripper lifting load 68

5.5 Discussion 71

5.5.1 Designing the gripper 71

5.5.2 Fabrication process of gripper 72

5.5.3 Gripper function and ability 72

6. CONCLUSION AND RECOMMENDATION 73

6.1 Conclusion 73

6.2 Recommendation 74

6.2.1 Design Aspects 74

6.2.2 Mechanical Structure Aspects 74

REFERENCE 76

ix

LIST OF FIGURE

Figure 2.1: Type of Gripper 8

Figure 2.2: The effect of an assign tolerance 11

Figure 2.3: Mathematical models of tolerance accumulation 11

Figure 2.4: Size Tolerance 13

Figure 2.5: Form Tolerance 13

Figure 2.6: Location Tolerance 14

Figure 2.7: Orientation Tolerance 14

Figure 2.8: Graph of Density (kg/m3) Versus Young’s Modulus (GPa) 15

Figure 2.9: HDPE material that use for base of the end arm 16

Figure 2.10: Application and product from PTFE material 18

Figure 2.11: Neoprene sheet 18

Figure 2.12: Robot end effectors that built using aluminum 19

structures as the main component

Figure 2.13: Carbon Fiber Wheel Tubs (47" Dia.) 22

Figure 2.14: The comparison of the material that choosen in gripper

fabrication 24

Figure 2.15: Example of piece of material that using Laser cutting 26

Figure 2.16: Turning process to manufacture shaft in accurate 28

shape and dimension

Figure 2.17: Shaft usually using turning method to achieve 28

desires diameter and shape

Figure 2.18: Milling process 29

Figure 2.19: Illustrated of the process at the cutting area 30

Figure 2.20: Illustrates a cross section of a hole being cut by 31

a common twist drill

Figure2.21: Components for this robotic gripper were first prototyped, then

manufactured,using FDM (Fused Deposition Modeling) 31

Figure 2.22: Example of bolt, machine screw 33

Figure 3.1: Flow of work process of developing gripper 38

x

Figure 3.2: The first design of gripper 39

Figure 3.3: The finalize design of gripper 40

Figure 4.1: Gripper flow of fabrication process 48

Figure 4.2: Diagram of fabrication process of gripper 50

Figure 4.3: Base fabrication 51

Figure 4.4: Robot Mount fabrication 51

Figure 4.5: Grippert Mount fabrication 52

Figure 4.6: Supporter fabrication 53

Figure 4.7: Slider fabrication 53

Figure 4.8: Supporter + Base Bracket fabrication 54

Figure 4.9: Rod fabrication 54

Figure 4.10: Guide Bar fabrication 54

Figure 4.11: Guide Bar + Base Bracket fabrication 55

Figure 4.12: Finger holder fabrication 56

Figure 4.13: Finger fabrication 56

Figure 4.14: Holder fabrication 57

Figure 4.15: Pneumatic cylinder model SMC CQ1 61

Figure 4.16: Cylinder that mounting to the gripper 61

Figure 5.1: Conceptual design 63

Figure 5.2: The succesful gripper development 64

Figure 5.3: The gripper grasps the 1 kg sugar pack 69

Figure 5.4: The gripper ungrasps the 1 kg sugar pack 69

Figure 5.5: The gripper grasps the 2 kg sugar pack 70

Figure 5.6: The gripper ungrasps the 2 kg sugar pack 70

xi

LIST OF TABLE

Table 2.1: Summarize of part characteristics and associated 9

end effector solutions

Table 2.2: International Tolerance (IT) grades 13

Table 2.2: Table of HDPE Properties 17

Table 2.3: Comparison of plastic that has been select for gripper fabrication 23

Table 2.4: Comparison of metal that has been select for gripper fabrication 24

Table 2.5: Material thickness requirement in LCM 26

Table 3.1: Example of machining process that use to machining parts 42

Table 4.1: Materials and components that used in gripper development. 46

Table 4.2: Gripper assembly process 58

Table 5.1: Gripper parts and function 66

Table 5.2: Gripper movement 68

1

CHAPTER 1

INTRODUCTION

1.1 Overview

The design of the end-of-arm tooling for a robotic assembly system is very important for

reducing errors and decreasing cycle times. This is the piece of the robotic parts handler

or assembler that physically interacts with the environment. While many factors may be

blamed for the common failures of workcells, the culprit is very often the grippers. Well

designed grippers can increase throughput, improve system reliability, compensate for

robot inaccuracy, and perform value added functions to the assembly.

According to dictionary of McGraw-hill（2003）, gripper is define as a component of

robot that grasp an object, generally through the use of suction cups, magnets, or

articulated mechanism. Gripper provides the capacity to do a wide variety of

manipulative task. Robotic hand or gripper is the integral part in most of the robot

application. A robot arm itself can serve no purpose until a load or a tool is suspended

from or attached to it. The robotic application in assembly and material handling is

growing more rapidly in industrial environment. Thus, design of robotic gripping

mechanism always becomes the key element for a specific operation.

Guo et al, (1992) explained that the main function of a gripper is to grasp and to release

workpieces during the material transfer route. Generally, the gripper for industrial robots

is a specialized device that is used to handle only one or a few objects of similar shape,

size and weight in a repetitive operation, which requires minimum gripping dexterity

and is limited in its versatility. However, in other applications, the robot gripper will be

2

required to handle many different objects of varying weights, shapes, and material.

Then, we shall refer to a more universal or versatile grippers. Gripper types will be

discussed furthers in literature review.

Arthur G. Erdman (1986) mention that the design of the gripper systems is not a trivial

task. Unfortunately, the finalized parts and assembly sequence are often given to the

designer, who must then devise grippers to handle the parts and perform the assembly. It

is much more desirable for the design of the grippers to occur concurrently with the

design of the rest of the system. Often a small feature added to a part can greatly

increase the reliability of the gripper. Other times, a proper gripper design can simplify

the overall assembly, increase the overall system reliability, as well as decrease the cost

of implementing the system.

The gripper is the mechanical interface between the robot and the work and the device

with which the robot performs its programmed handling functions. Correctly selecting

the gripper for an application is essential to the success of the application. Arthur G.

Erdman (1986) explained that gripper selection is a may not be an easy task since there

are wide variety of gripper types and configurations and many different factors to

consider. Information on the factors which are relevant to the selection process is

incomplete and tends to be qualitative. The material available and ease or manufacturing

is also an important consideration.

The end of the manipulator is the part the user or robot uses to affect something in the

environment (Spencer, 2005). For this reason it is commonly called an end-effector, but

it is also called a gripper since that is a very common task for it to perform when

mounted on a robot. It is often used to pick up dangerous or suspicious items for the

robot to carry, some can turn doorknobs and others are designed to carry only very

specific things like beer cans. Even for semi-autonomous robots where a human controls

the manipulator, using the gripper effectively is often difficult. For these reasons, gripper

design requires as much knowledge as possible of the range of items the gripper will be

expected to handle. Their mass, size, shape, strength, etc. all must be taken into account.

3

In this study, a robot gripper that has been design by the previous students is required be

to fully analyses for its physical properties when handling load. Solid Work will be use

as the analysis software for finite element analysis to the gripper. Finally, the gripper has

to go through workspace testing by using simulation software to observe its performance

in real time working situation.

1.2 Problem Statement

The mechanism and development of robotic gripper is highly complex and environment

dependent. To deal with complexity, the entire design project has to be broken down into

several sub problems which are then treated independently as optimization problem.

However, the constraints are generally dependent on each other. In this project, problem

occur due finding the best way to fabricate the gripper. Furthermore, the existing design

must be revised to mention the gripper able to grasp object with 5 kg payload.

The study of this project is focus on improvement and continuation work on the previous

PSM project which is a 10kg payload gripper for Comau robot. Then, study of the

manufacturing process of the gripper and fabricate it. Basically the gripper design has

been carried out in the last PSM. Since the current task is design analysis on 5kg payload

gripper for Comau robot, this mean there would be a little improvement to the previous

design and finally the gripper is fabricate assemble on Comau Robot.

Often, very little time is spent in optimal kinematics structure design in the early stages

of a design process. D. T. Pham (1988) describes that a time pressures sometimes force

engineers to repeat topologies that have worked in similar application in the past rather

than try to create better design. It is always encourages to follow the previous design

unless the design analysis really proven that it was not good. Thus, modification and

optimization are requires to upgrade the design to achieve a better performance.

4

Generally, a physical prototype is necessary to truly test a hand’s ability to perform

tasks, but this can be quite costly and design changes are not easy to make. Thus it

would need a simulation system that able to load a gripper hand design, to interact with

it and perform grasps of objects, and to visualize and evaluate the space of performance

and error that might occurs. After simulation have been perform well, the design is

fabricated and assemble it with Comau robot to done the task.

1.3 Objectives

The objective of this project is to fabricate and assembled gripper to perform a pick and

place operation for 5kg payload boxes. Below are important objective has to be

achieved:

a) To improve the design and relevent aspect.

b) To develop the gripper prototype

c) To carry out functional testing on the gripper

1.4 Scope

The scope is focused on related aspect in this project so that the objectives are able to

accomplish. Scope on this project will cover up the below task:

a) Revisit the existing design

b) Develop, fabricate and assembly the gripper.

c) Testing the gripper performance and functional ability.

6

CHAPTER 2

LITERATURE REVIEW

2.1 Overview

Motion devices imitate the movements of people, in the case of the gripper, it is the

fingers. S. H. Yeo (1988) said that gripper is a device that holds an object so it can be

manipulated. It has the ability to hold and release an object while some action is being

performed. The fingers are not part of the gripper, they are the specialized custom

tooling used to grip the object and was referred as a “jaw”

In robotics, an end effector is a device or tool that's connected to the end of a robot arm

where the hand would be. The end effector is the part of the robot that interacts with the

environment. The structure of an end effector and the nature of the programming and

hardware that drives it depend on the task the robot will be performing.

In manufacturing, a robot arm can accommodate only certain tasks without changes to

its end effector's ancillary hardware and/or programming. If a robot needs to pick

something up, a type of robot hand called a gripper is the most functional end effector. If

a robot needs to be able to tighten screws, however, then the robot must be fitted with an

end effector that can spin.

Maximum payload is the weight of the robotic wrist, including the EOAT and

workpiece. It varies with different robot applications and models.

7

2.1.1 Operation

The most widely used gripper is the pneumatically powered gripper; it is basically a

cylinder that operates on compressed air. When the air is supplied, the gripper jaws will

close on an object and firmly hold the object while some operator is performed, and then

the air direction will change and the gripper will release the object. Typical uses are to

change orientation or to move an object in a pick-n-place operation.

2.2 Gripping Action

2.2.1External:

This is the most popular method of holding objects, it is the most simplistic and it

requires the shortest stroke length. When the gripper jaws close, the closing force of the

gripper holds that object.

2.2.2 Internal:

In some applications, the object geometry or the need to access the exterior of the object

will require that the object is held from the center. In this case the opening force of the

gripper will be holding the object.

8

2.3 Types of Grippers

The most popular types of grippers are the 2 jaw parallel and 2 jaw angular gripper

styles. Parallel grippers open and close parallel to the object that it will be holding, these

are the most widely used grippers. They are the simplest to tool and can compensate for

some dimensional variation. Angular grippers move the jaws in a radial manner to rotate

the jaws away from the object and therefore require more space.

Figure 2.1: Type of Gripper (Yeo 1988)

2.4 Existing Gripper Analysis

2.4.1 Major Factors in Choosing a Gripper and Jaw Design

a) Part shape, orientation and dimensional variation

Two jaw parallel gripper is desired if the object has two opposing flat surfaces,

since it can handle some dimensional variation. Jaws can also be designed to

handle cylindrical objects with the 2 jaw concept. Keep in mind that retention or

encompassing grip requires much less force.

9

Table 2.1: Summarize of part characteristics and associated end effector solutions

Part Characteristics Gripper Characteristics

Size,

weight

Large, heavy Grippers using wrap grips

- taking advantage of friction or vacuum or electromagnetic

holding

Small, light Two-fingered gripper

vacuum cup if smooth surface

electromagnet if ferrous alloy

Shape Prismatic Two-fingered parallel-jaw gripper; angular motion if all parts have

approximately same dimensions

Cylindrical if light: use parallel or angular motion two-finger gripper with V-

jaw fingertips

if heavy: use wrap gripper

- consider gripping on end with three-finger gripper if task or

fixtures permit

Flat Parallel or angular motion gripper or vacuum attachment

Irregular Wrap grasp using linkages or bladder consider

- augmenting grasp with vacuum or electromagnetic holding

for heavy parts.

Surface Smooth Good for vacuum attachments, simple electromagnets, two-

fingered grippers with flat fingertips

Rough Compliant material (e.g., low durometer rubber) on fingertips or

compliant membrane filled with powder or magnetic particles.

- grippers that use a wrap grasp are less sensitive to variations

in surface quality.

Slippery Consider electromagnet or vacuum to hold

- grippers that use a wrap grasp are less sensitive to variations in

friction

Material Ferrous Electromagnet

- concerns that do not rule out the presence of strong magnetic

fields

Soft Consider vacuum or soft gripping materials

Very delicate Soft wrap grippers and vacuum grippers so can grip gently

- compliant fingertips with foam rubber use to distribute the

contact pressure

if the part is very light and fragile consider lifting it using the

Bernoulli effect

b) Gripper Weight:

Grip force must be adequate to secure the object while a desired operation is

performed on the object. The type of jaw design must be part of the force

requirement. Keep in mind that you should add a safety factor to the amount of

force that you select and air pressure is a factor to keep in mind.

10

c) Accessibility

This applies both to the work being performed on the object and the amount of

room for the gripper jaws. If the work is to the exterior of the object then it may

require an internal grip. Angular grippers are usually less expensive but require

additional space for jaw movement.

d) Environmental

Harsh environment or clean room applications require grippers designed for

those purposes.

e) Retention of the Object

When air pressure is lost, the gripper will relax its grip on the object and the

object may be dropped. There are spring assist grippers designed for this type

application.

2.4.2 Tolerance Analysis

Alan R. Parkinson (1991) in his articles mentioned that tolerance management is a key

element in their programs for improving quality, reducing overall costs and retaining

market share. The specification of tolerances is being elevated from a menial task to a

legitimate engineering design function. New engineering models and sophisticated

analysis tools are being developed to assist design engineers in specifying tolerances on

the basis of performance requirements and manufacturing considerations. Koenderink

and van Doorn (1987) performed a tolerance analysis to measure the extent to which

certain information is available in velocity flow fields