ABSTRACT Robots utilization in automotive industry has been greatly expanded because of its importance in automotive factories. Factories are well suited for robotic automation because many tasks in the manufacturing tend to be repetitive, dangerous and heavy. Among the most widely used robotic assisted operation in the automotive industry is welding process. This is due to the nature of welding operation itself where the job is normally done under repetitive and continuous condition. Besides, utilization of robot would also increase welding accuracy consistently. There are two main goals of this project. The first goal is to analyze articulated robots that would execute spot welding process on the car body. Second goal is to propose the design of a suitable robotic manufacturing system (RMS) to execute spot welding operation for automotive industry. Kinematics analysis, path planning analysis, robot programming and also simulation of the working robots will be carried out throughout the studies in order to analyze the entire robot manufacturing system that will be proposed. By conducting this study, the process of designing and analysis the robot manufacturing system for automotive industry can be deeply understood. The outcomes of this study could be used to establish a RMS in automotive industry. i

ABSTRAK Penggunaan robot dalam industri automotif telah banyak berkembang atas kepentingannya dalam kilang-kilang automotif. Automasi robotik merupakan penyelesaian yang baik untuk pengeluaran kilang automotif ini kerana kebanyakan aktiviti industri pembuatan disifatkan sebagai berulang, berbahaya dan berat. Proses pengimpalan merupakan antara operasi pengeluaran kilang automotif yang banyak bergantung kepada penggunaan aplikasi robotik. Ini disebabkan proses pengimpalan memerlukan operasi yang berulangan dan berterusan. Selain itu, penggunaan robotik juga membantu dalam meningkatkan kualiti hasil kerja pengimpalan. Projek ini mengandungi dua tujuan. Pertamanya adalah untuk menganalisa articulated robot yang akan melaksanakan operasi pengimpalan ke atas struktur utama sesebuah kereta. Tujuan yang kedua adalah untuk mencadangkan satu sistem pembuatan robotik yang akan menjalankan proses pengimpalan dalam industri automotif. Analisa kinematik, analisa perancangan laluan, pengaturcaraan robot dan simulasi ke atas fungsi-fungsi robot akan dilaksanakan sepanjang kajian projek ini supaya satu analisa lengkap tentang sistem pengeluaran robotik yang dicadangkan dapat diungkapkan dengan tepatnya. Sebagai hasil kajian, pemahaman dalam proses merekabentuk and analisa ke atas system pengeluaran robotic dalam industri automotif akan dapat ditingkatkan. Hasil kajian ini juga diharapkan dapat membangunkan satu sistem pengeluaran robotik yang mantap untuk kesesuaian industri automotif. ii

DEDICATION To my beloved family and friends. iii

ACKNOWLEDGEMENT I would like to express my gratitude to my supervisor, Dr. Zamberi bin Jamaludin for his support, encouragement, supervision and useful suggestions throughout this research work. His continuous guidance enabled me to complete my study successfully. I would also like to thank Mr. Muhammad Hafidz Fazli B. Md Fauadi, my ex-supervisor for his encouragements and enthusiastic helps in the first part of the study. I am truly grateful of their knowledge sharing and time spending in order to help me to complete the project. Besides, I am ever, indebted to my parents for their love and support throughout my life. Although they did not contribute much in the information in the thesis, their moral supports are more than enough for me to overcome all the challenges I met during the study. I would also like to thank my brother for providing me a good computer for me to use the software related and to complete my thesis. Without him, my thesis could not be completed too. I am truly grateful to some of my beloved friends that help me a lot in completing this thesis. I appreciate all the help and advice given from them especially Mr. Lau Ong Yee who had guided me about the direction of my thesis from the beginning and Mr. Chan Seng Kiong who has overcome some of my doubts on several matters. Their opinions and knowledge sharing helps me a lot when doing research on this study. Not to forget, I appreciate the time shared and opinions exchanged with all my lovely housemates especially during the rush hours to complete the thesis. Last but not least, special thanks to individuals not mentioned that had been directly and indirectly help me in this project. All your helps and supports are very well appreciated. Thank you. iv

TABLE OF CONTENT Abstract Abstrak Dedication Acknowledgement Table of Content List of Tables List of Figures List of Abbreviations i ii iii iv v ix x xii 1. INTRODUCTION 1 1.1 Background 1 1.2 Problem Statements 3 1.3 Objectives 4 1.4 Scope of Study 4 1.5 Summary 4 2. LITERATURE REVIEW 5 2.1 Introduction 5 2.2 History of Robot 6 2.2.1 What is Robot? 6 2.2.2 Robot Timeline 6 2.3 Classification of Robots 8 2.3.1 Cartesian Robot 8 2.3.2 Cylindrical Robot 9 2.3.3 Spherical Robot 10 v

2.3.4 Articulated Robot 10 2.4 Basic Components of a Robot System 12 2.4.1 Manipulator 12 2.4.2 End effector 12 2.4.3 Actuators 13 2.4.4 Sensory Devices 13 2.4.5 Controller 14 2.5 Robot Motion 14 2.5.1 Point to Point Control (PTP) 14 2.5.2 Continuous Path Control 16 2.6 Robot Applications 17 2.6.1 Welding 17 2.6.2 Spray Painting 18 2.6.3 Palletizing and Material Handling 19 2.6.4 Assembly Operations 20 2.7 Kinematics Analysis 21 2.7.1 Forward Kinematics 22 2.7.1.1 Rotation Transformations 22 2.7.1.2 Homogeneous Transformations 24 2.7.1.3 Denavit Hartenberg Algorithm 26 2.7.2 Trajectory Planning 28 2.7.2.1 Trajectory Planning with Polynomials 29 2.7.2.2 Polynomials Trajectories with Via Points 29 2.8 Spot Welding 30 2.8.1 Spot Welding Robot 31 2.8.2 Robotic Welding System 32 2.9 Offline Programming and Simulation 33 2.9.1 Robotic Workspace Simulation Models 34 2.9.1.1 Create Part Models 35 2.9.1.2 Building Device Models 35 vi

2.9.1.3 Positioning Device Models in Layout 35 2.9.1.4 Defining Devices Motion Destination in Layout 36 2.9.1.5 Device Behavior and Programming 36 2.9.1.6 Executing Workspace Simulation and Analysis 36 2.9.2 Robot Simulation 37 2.10 Summary 37 3. METHODOLOGY 38 3.1 Introduction 38 3.2 Planning of Study 38 3.3 Project Methodology 41 3.3.1 Problem Statements and Objectives 42 3.3.2 Research and Analysis of Study 42 3.3.3 Robot/Tool Selection 43 3.3.4 Kinematics Analysis 43 3.3.5 Workspace Design 44 3.3.6 Programming 44 3.3.7 Simulation 45 3.3.8 Discussions and Conclusion 45 3.4 Summary 45 4. ROBOT WORKSPACE DESIGN 46 4.1 4.2 4.2.1 4.2.2 4.2.3 4.2.4 4.3 4.4 Introduction Workspace Design Workstation Spot Welding Robot Assistant Handling Robot Components to be Weld Working Process of Workstation Summary 46 46 47 49 50 51 52 55 vii

5. RESULT AND ANALYSIS 56 5.1 5.2 5.3 5.3.1 5.3.2 5.4 5.4.1 5.4.2 5.5 5.6 Introduction Simulation Results Programming of Robots Behaviour Spot Weld Gun Class Module Gripper Class Module Kinematics Analysis Forward Kinematics of Spot Welding Robot Forward Kinematics of Assisting Robot Path Planning Summary 56 56 59 59 61 63 63 67 71 75 6. DISCUSSION 76 6.1 6.2 6.3 6.4 6.5 6.6 Introduction Forward Kinematics Path Planning Workstation Arrangements Spot Welding Process Summary 76 76 77 80 84 86 7. CONCLUSIONS 87 7.1 7.2 Conclusions Future Work and Recommendations 87 89 REFERENCES 90 viii

LIST OF TABLES 2.1 Timelines of Robots 7 2.2 Four Arm Parameters 27 3.1 Gantt Chart of PSM I 39 3.2 Gantt Chart of PSM II 40 5.1 Arm Parameters of Spot Welding Robot 63 5.2 Arm Parameters for Assisting Robot 67 6.1 Welding Parameters 85 ix

LIST OF FIGURES 1.1 Spot welding of a car body in an assembly line 2 1.2 Spot welding 3 2.1 Cartesian robot 9 2.2 Cylindrical robot 9 2.3 Spherical robot 10 2.4 Articulate robot 11 2.5 The PTP motion 15 2.6 The continuous path motion 16 2.7 Welding application 18 2.8 Robot spot welding car body 18 2.9 Spray painting 19 2.10 Palletizing 20 2.11 Material Handling 20 2.12 Assembly process of a car 21 2.13 Relationship of forward and inverse kinematics 21 2.14(a) Roll 22 2.14(b) Pitch 22 2.14(c) Yaw 23 2.15 A transformation that consists rotation and translation 24 2.16 The four values (θ, d, a, α) identified relating one joint to the next 26 2.17 Polynomial trajectories with via points 30 2.18 Spot welding 30 2.19 Process to determine robotic work space simulation 34 2.20 Robot simulation process 37 x

3.1 Methodology of the complete study 41 4.1 Arrangement of components in the workstation 48 4.2 Spot welding robot (ABB 6400 series) 49 4.3 End-effector of spot welding robot (C spot weld gun) 49 4.4 Assisting robot (ABB 6400 series) 50 4.5 Robot tool for pick and place 50 4.6 Car body 51 4.7 Roof of the car 51 4.8 Roof transferred by assisting robot while spot welding robots 52 ready in position 4.9 Welding route of both spot weld robots 53 4.10 Spot welding process ongoing while assisting robot holding the roof 53 4.11 Process flow of the spot welding process of car roof 54 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 Assisting robot grasping the roof Assisting robot holding roof while spot welding robots move to first welding position Spot welding robots welding at the second path Spot welding completed and parts transferred to next station Coding for spot weld gun Coding for gripper Graph of distance versus time Graph of speed versus time Graph of acceleration versus time 57 57 58 58 60 62 74 74 74 6.1 6.2 6.3 6.4 6.5 Path planning for robots system Working envelopes for spot welding robots Working envelope for assisting robot Working envelope for all three robots Space for future allocation of new robot 79 81 81 82 83 xi

LIST OF ABBREVIATIONS CAD - Computer Aided Design D-H - Denavit Hartenberg DoF - Degree of Freedom GP - Geometry Points ISO - International Organization for Standardization PC - Personal Computer PTP - Point to Point RMS - Robot Manufacturing System RUR - Rossum s Universal Robots UTeM - Universiti Teknikal Malaysia Melaka VBA - Visual Basic for Applications xii

CHAPTER 1 INTRODUCTION 1.1 Background Robots are generally designed to help people with tasks that would be difficult, unsafe, or boring for a real person to do alone. Nowadays, about 90% of the robots are found in industries and more than 50% of robots today are deployed in automotive industries (Pinto, 2008), (Mittal and Nagrath, 2002). In today s economy, robots are very useful especially in automotive industries as it need to be efficient to cope with the competition from other competitors. This is because robot can do certain tasks more efficiently than humans such as (Mittal and Nagrath, 2002): a) Handling dangerous materials b) Assembling products c) Spray finishing d) Polishing and cutting e) Inspection f) Repetitive, backbreaking and unrewarding tasks g) Task involving danger to humans or dangerous tasks By using robots, a more profitable and competitive manufacturing operations can be obtained by utilizing technology from the robots. There are many operations and processes carried out by robots in the automotive industry where spot welding is one of the important processes. In one of the car factory in German, spot welding robots are consists of about 207 among their 230 robots in the whole building (Mortimer, 2001). 1

Spot welding in automobile manufacturing industry is used almost universally to weld the sheet metal to form a car. Spot welders can also be completely automated, and many of the industrial robots found on assembly lines are spot welders. The automotive industry prefers spot welding because it is a simple and cost-effective joining method. Spot welding is performed on thousands of spots for every passenger vehicle; therefore, each welded spot has its own importance not only with regard to quality but also for production manufacturing. Figure 1.1 shows the application of spot welding in the car manufacturing assembly line. Figure 1.1 : Spot welding a car body in an assembly line (http://europeforvisitors.com, 2008) Spot welding is the simplest and most common used resistance-welding process. This type of welding may be performed by means of single or multiple pairs of electrode and the required pressure is supplied through mechanical or pneumatic means as shown in Figure 1.2. Spot welding can be defined as autogeneous fusion welding process where heat is generated by the tips of two opposing cylindrical electrodes touching a lap joint of two sheet metal (Poggio et al, 2005), (Kalpakjian, 2006). The shape and surface condition of the electrode tip and the accessibility of the site are important factors in spot welding. A variety of electrode shapes are used to spot weld areas that are difficult to reach. Accurate control and timing of the electric current and the pressure are also essential in spot welding. In the automotive industry, the number of cycles range up to about 30 at a frequency of 60 Hz (Kalpakjian, 2006). 2

Figure 1.2 : Spot welding (Poggio et al, 2005) 1.2 Problems Statements Spot welding is the most common application being applied in the automotive industry as this process involved dangerous working environment, repetitive procedures and many other aspects. The welding process could not be safely done by human being and there are many other safety and ergonomics factors are taken into consideration when performing the process manually. On top of that, the repetitive procedures of the process are not suitable to be done by human as it will cause boredom and lead to human errors. Hence, spot welding robots are needed in the manufacturing not only for high quality products but at the same time to provide high productivity. Robots work much faster, more efficiently and with less risk of accident than humans in certain jobs, and they can make sure there are no bottlenecks in the process. In spot welding, there are important parameters which are the electrical resistance, electrical current, contact pressure and timing (Poggio et al, 2005). All parameters are highly dependant on one another and a small variation in one of the parameter will strongly influence the result of the welding process. 3

Besides, the suitable working area for the spot welding robots is also very important as there will always be a few robots performing tasks at the same time on the same component. A well-designed work space is very important to prevent robot collisions and also spaces available for future maintenances. 1.3 Objectives The purpose of this project are : a) To analyze articulated robots that are suitable to execute spot welding process in the automotive industries. b) To design a suitable working area for spot welding robot that includes assistance handling robot, jig and fixtures, and material handling. c) To analyze and simulate the designed robot manufacturing system to perform the spot welding process. 1.4 Scope of Study Automobile bodies can have as many as 10,000 spot welds where each are welded at high rates using multiple electrodes (Kalpakjian, 2006), (Pelagagge, 1997). Hence, the scope of this study will be narrowed down to the spot welding process of only one part of the car body. Design and analysis of the robot will be done and tested using the WORKSPACE simulation software. 1.5 Summary In this chapter, the objectives, scope and problem statements of the title have been briefly introduced. Besides, the background of the title had also been discussed so that there is more understanding on the title of the study to be conducted. It is necessary to understand the introduction of the study because more detail information will be discussed in the following chapters. 4

CHAPTER 2 LITERATURE REVIEW 2.1 Introduction In this chapter, sources from journals, case studies and articles related are summarized. All the information obtained will act as a guideline or references for this study field. Analysis and detail research are done from these information obtained to compile in this report for better exposure and understandings. Robots are capable of performing many different tasks and operations precisely and do not require common safety and comfort elements need. However, it takes much effort and many resources to take a robot function properly. Hence, various types of research and studies need to be done from various reading materials and the global search engine on all the related information required in this study field. When it comes to robots, reality still lags science fiction. But, just because robots have not lived up to their promise in past decades does not mean that they will not arrive sooner or later. Indeed, the confluence of several advanced technologies is bringing the age of robotics ever nearer; smaller, cheaper, more practical and costeffective. 5

2.2 History of Robot 2.2.1 What is Robot? The Robot Institute of America (1979) defined a robot as a re-programmable, multifunction manipulator designed to move material, parts or specialized devices through variable programmed motions for performance of a variety of tasks. However, there are many other definitions for robots where the encyclopedia defines a robot as a stand alone hybrid computer system that performs physical and computational activities. In addition, robots are capable of performing many different tasks as it is a multiple-motion device with one or more arms and joints. Another definition given by the International Organization for Standardization (ISO) in ISO 8373 states that robot is an automatically controlled, reprogrammable, multipurpose, manipulator programmable in three or more axes, which may be either fixed in place or mobile for use in industrial automation applications. The acclaimed Czech playwright Karel Capek (1890-1938) made the first use of the word robot. The word robot is originated from the Czech word robota which means slave laborer. The use of the word robot was introduced into his play R.U.R. (Rossum's Universal Robots) which opened in Prague in January 1921. There are no an exact definition of robot which can satisfy everyone and many people have their own definitions. However, it can be generally concluded that from the above mentioned definitions, the programmable and re-programmable multifunctions are the most important features of a robot system. 2.2.2 Robot Timeline Table 2.1 shows that robot has been evolved greatly since it has been from the first development from the respective inventor. 6

Table 2.1 : Timelines of Robots (http://en.wikipedia.org, 2008) Year Significance Robot Name Inventor 1206 First programmable humanoid robots 1495 Designs for a humanoid robot Boat with four robotic musicians Mechanical knight Al-Jazari Leonardo da Vinci 1738 Mechanical duck that was able to eat, flap its wings, and excrete Digesting Duck Jacques de Vaucanson 1800s Japanese mechanical toys that served tea, fired arrows, and painted Karakuri toys Hisashige Tanaka 1921 1930s First fictional automatons called "robots" appear in the play R.U.R. Humanoid robot exhibited at the 1939 and 1940 World's Fairs Rossum's Universal Robots Elektro 1948 Simple robots exhibiting biological behaviors Elsie and Elmer Karel Čapek Westinghouse Electric Corporation William Grey Walter 1956 First commercial robot, from the Unimation company founded by George Devol and Joseph Engelberger, based on Devol's patents Unimate George Devol 1961 First installed industrial robot Unimate George Devol 1963 First palletizing robot Palletizer Fuji Yusoki Kogyo 1973 First robot with six electromechanically driven axes Famulus KUKA Robot Group 1975 Programmable universal manipulation arm, a Unimation product PUMA Victor Scheinman At year 1989, the first biped walking robot which was able to walk on a terrain stabilized by trunk motion was developed by Kato which is named, WL12RIII (Jaeger, 2004). It could walk at a rate of 2.6 seconds, up and down stairs. Then robots revolved to another form where Honda creates P2, the first major step in creating their ASIMO in year 1996. P2 is the first self-regulating, bipedal humanoid robot created. 7

At year 2002, Honda creates the Advanced Step in Innovative Mobility (ASIMO). It is intended to be a personal assistant. It recognizes its owner's face, voice, and name. ASIMO can read email and is capable of streaming video from its camera to a PC. While at year 2005, The Korean Institute of Science and Technology (KIST), creates HUBO, and claims it is the smartest robot in the world. This robot is linked to a computer via a high-speed wireless connection; the computer does all of the thinking for the robot (Jaeger, 2004). 2.3 Classification of Robots Industrial robots are categorized by the first three joint types which are the prismatic/translational (linear) joint and rotational joints. These two types of joint is the most current used in industrial robots. There are four different types of robot configurations which are : a) Cartesian b) Cylindrical c) Spherical d) Articulated 2.3.1 Cartesian Robot This type of robot has the first three joints corresponding to the major axes which are all prismatic (PPP) as shown in Figure 2.1. This type of robot is commonly used for positioning tools such as dispensers, cutters, drivers and routers (Parker, 2008). The primary applications of this robot are in material handling, machine loading and printer board construction. The advantages of Cartesian robot are that the configuration and design are simple, motion control in Cartesian space can be easily carried out and large work envelop. The robot will be easier to visualize and have better inherent accuracy than most other types besides easier to be program offline. On the other hand, the limitations of this type of robot are that it is not space efficient and the external frame can be massive. 8