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STUDY OF REPEATABILITY
OF ROBOT
MANIPULATOR
Wan Mohd Shaham Bin Wan Ma'sor
Bachelor of Engineering with Honours
TJ (Mechanical Engineering and Manufacturing Systems)
211 2004
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P. KHIDMAT MAKLUMAT AKADEMK
UNIMAS
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1000125805PERFORMANCE STUDY OF REPEATABILITY OF ROBOT MANIPULATOR
WAN MOHD SHAHAM BIN WAN MA'SOR
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This project is submitted in partial fulfillment of
the requirements for the degree of Bachelor of Engineering with Honours (Mechanical Engineering and Manufacturing System)
Faculty of Engineering
UNIVERSITI MALAYSIA SARAWAK 2004
Universiti Malaysia Sarawak
BORANG PENYERAHAN TESIS
Judul:
Saya
Performance Study of Repeatability of Robot Manipulator SESI PENGAJIAN: 2000-2004
WAN MOHD SHAHAM BIN WAN MA'SOR
mengaku membenarkan tesis ini disimpan di Pusat Perkhidmatan Akademik, Universiti Malaysia Sarawak dengan syarat-syarat kegunaan seperti berikut:
I. Hakmilik kertas projek ini adalah di bawah nama penulis melainkan penulisan sebagai projek bersama clan dibiayai oleh UNIMAS, hakmiliknya adalah kepunyaan UNIMAS.
2. Naskah salinan di dalam bentuk kertas atau mikro hanya boleh dibuat dengan kebenaran bertulis daripada penulis.
3. Pusat Khidmat Maklumat Akademik, UNIMAS dibenarkan membuat salinan untuk pengajian mereka.
4. Kertas projek hanya boleh diterbitkan dengan kebenaran penulis. Bayaran royalty adalah mengikut kadar yang dipersetujui kelak.
5. * Saya membenarka perpustakaan membuat salinan kertas projek ini sebagai bahan pertukaran di antara institusi pengajian tinggi.
6. ** Sila tandakan ( vO
SULIT (Mengandungi maklumat yang berdarjah keselamatan atau kepentingan Malaysia seperti ynag termaktub di dalam AKTA RAHSIA RASMI 1972). TERHAD (Mengandungi maklumat TERHAD yang telah ditentukan oleh
organisasi/badan di mana penyelidikan dijalankan). TIDAK TERHAD
Disahkan oleh:
yiýE-
(TAN ATANGAN PENYELIA) ALAMAT TETAP:
8 1444 Kg Batu Hitam, 26100 Kuantan,
Pahang Darul Makrour.
Tarikh: º5
JI
J
Amº1 CATATAN * ** ERVINA JUNAIDI (Nama Penyelia) Tarikh: K/ e /0 LPotong yang tidak berkenaan.
Jika Kertas Projek ini SULIT stau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi berkenaan dengan menyertakan sekali tempoh
Approval Page
The project report attached here to, entitled "Performance Study of Repeatability of Robot Manipulator" prepared and submitted by WAN MOHD SHAHAM BIN WAN MA'SOR in partial fulfilment of the requirement for Bachelor of Engineering with Honours in Mechanical Engineering and Manufacturing System is hereby read and approved by: Mrs. Ervina Junaidi, Supervisor
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DateMarch 2004
Dedication
To my parents for their love, support and great expectation
Acknowledgements
Praise to Allah! May Allah's peace and blessing upon Prophet Muhammad, his family and companions, and those who follow their guidance.
I would like to thank my supervisor, Mrs. Ervina Junaidi for all the support and help in leading the project to its culmination. Although busy with her responsibilities still makes time to accommodate me whenever I need her advice. Also my co-supervisor, Mr. A. Rahim Md. Amin for his time in giving suggestion and answering my question regarding to Robotic and Statistical Control Process. A special acknowledgement goes to my parent; Mr. Wan Ma'sor Mamat and Mrs. Hasnah Ismail for their great moral support along the way accomplish the project. Not forget, Mechanical Engineering and Manufacturing System's lab assistant, Mr. Masri for being gracious in helping his best whenever I encounter problem/ question due to robot manipulator and following friends: Ainin Afizah Parnon, Alexon Jong Sze Chien, Wan Sharuzi Wan Harun and Muhammad Syafik Jumali for their ideas and helps.
ABSTRACT
Performance of repeatability is one of the criteria for robot manipulator selection to match the requirements of the tasks to be done. The purpose of this project was to study the performance of repeatability for Mitsubishi Micro Robot
MELFA RV-MI's robot manipulator. There were two areas concerned: robot
manipulator speeds and lifting payloads carried by robot manipulator. With the introduction of different of robot manipulator speeds or lifting payloads carried by robot manipulator, the repeatability error changed accordingly. This corresponds to random errors once robot manipulator operated. The standard deviation of repeatability error under maximum speed and lifting payload, 8max obtained by experiment was compared with the theoretical value provided from the manufacturer.
A method based on amplified a small deviation occurred between a programmed point and return point is used. The robot manipulator was programmed to accomplished the experiment through the DENFORD Virtual Reality Robot Software and teach pendant box.
ABSTRAK
Kemampuan melakukan sesuatu kerja secara berulang alik adalah salah criteria dalam pemilihan robot manipulasi bersesuaian dengan kerja yang dilaksanakan. Tujuan projek ini untuk mengkaji kemampuan robot manipulasi Mitsubishi Micro Robot MELFA RV-Ml dalam melakukan kerja secara berulang alik.
Dua faktor yang dititikberatkan iaitu kelajuan robot manipulasi dan bebanan yang diangkat oleh robot manipulasi. Dengan kehadiran kepelbagaian kelajuan dan bebanan yang diangkat oleh robot manipulasi, kelemahan dalam kemampuan melakukan kerja secara berulang-kali berubah mengikut kadarannya. Ini berlaku disebabkan oleh kelemahan rawak ketika robot manipulasi melakukan kerja. Sisihan piawai kelemahan robot manipulasi di bawah kelajuan dan bebanan yang maksimum
ditentukan dari eksperimen, S, nax dan dibandingkan dengan nilai teori yang
disediakan oleh pihak pengilang.
Kaedah berdasarkan konsep pembesaran perbazaan antara titik yang diprogram dengan titik yang berulang alik diimplikasikan. Robot manipulasi yang digunakan telah diprogramkan menggunakan perisian DENFORD Virtual Reality Robot dan kotak pengajar robot.
Pusat Ak4de iak
UNIVERSITI MALAYSIA SARAWAK 94100 Kota Samarahan
Table of Contents
Page
APPROVAL PAGE DEDICATION ACKNOWLEGEMENTS ABSTRACT ABSTRAK LIST OF FIGURES LIST OF TABLESCHAPTER 1: INTRODUCTION
1.1 Overview of Industrial Robot 1.2 Robot Components 1.2.1 Manipulator 1.2.2 End Effector 1.2.3 Controller 1.2.4 Power Supply 1.3 Repeatability
1.4 Aims and Objectives
CHAPTER 2: LITERATURE REVIEW
2.1 Basic Terminology and Concept 2.1.1 Robot Configuration
2.1.2 Robot Coordinates
2.1.2 Tool Centre Point (TCP)
i ii 111 iv V vi ix
1
1 2 2 3 4 4 4 6 7 7 711
13
vi2.1.3 Work Envelope 14 2.1.4 Payload 14 2.1.5 Speed 15 2.1.6 Cycle 15 2.1.7 Accuracy 15 2.2 Robot Programming 16
2.3 Mitsubishi Micro Robot MELFA RV-M1 18
2.4 DENFORD Virtual Reality Robot Software 21
2.4.1 Virtual Reality 21
2.4.2 DENFORD Virtual Reality Robot Software 21
2.4.3 DENFORD Virtual Reality Robot's Main Interfaces 22
2.4.3.1 Superscape Viscape Main Viewing 22
2.4.3.2 VR Linker Main Control 24
2.4.3.3 Robot Control Panel 25
2.4.3.4 Edit Robot Memory 25
2.5 Concept of Repeatability 26
2.6 Manufacturer Method of Repeatability's Measurement 29
2.6.1 Principle of the Laser Tracking System (LTS) 29
2.6.2 Interferometer 31
2.6.3 Angular Encoders 31
2.6.4 Position Sensitive Diode (PSD) 31
2.6.5 CCD-Camera 32
2.6.6 Driving Unit 32
2.6.7 Digital Signal Processing System 32
2.6.8 High Precision Universal Joint 33
2.6.9 Tracking Controller 33
CHAPTER 3: METHODLOGY
3.1 Develop the Repeatability's Method 3.2 Program the Robot Manipulator
3.3 Collect and Analyze Result
CHAPTER 4: RESULTS AND DISCUSSIONS 4.1 Introduction
4.2 Results and Discussions
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS 5.1 Conclusion 5.2 Recommendation APPENDIXES REFERENCES 34 34
37
4042
42
44
55 5556
57 74 viiiList of Figures
Page
Figure 1.1 Basic of Robot's Components 2
Figure 1.2 Repeatability 5
Figure 2.1 Rectangular Configuration 8
Figure 2.2 Cylindrical Configuration 8
Figure 2.3 Spherical Configuration 9
Figure 2.4 Jointed-Arm Configuration 10
Figure 2.5 SCARA Configuration 10
Figure 2.6 Three Degrees of Freedom Associated with Wrist Motions 11
Figure 2.7 World Coordinates 12
Figure 2.8 Tool Coordinates 12
Figure 2.9 Joint coordinates 13
Figure 2.10 Tool Centre Point (TCP) 13
Figure 2.11 Work Envelope 14
Figure 2.12 Five D. O. F Robot Manipulator 19
Figure 2.13 Equipments of Mitsubishi Micro Robot MELFA RV-M 1 20
Figure 2.14 Superscape Viscape Main Viewing 23
Figure 2.15 VR Linker Main Control 24
Figure 2.16 Robot Control Panel 25
Figure 2.17 Edit Robot Memory
Figure 2.18 Determination of Repeatability
Figure 2.19 Result of Experiment of Repeatability
Figure 2.20 Principle of the Laser Tracking System (LTS)
26
27
28
29
Figure 3.1 Method to Measure Repeatability of Robot Manipulator 35
Figure 3.2 Determinations of Coordinate 38
Figure 3.3 Robot Script 39
Figure 4.1 Robot Manipulator Speeds 46
Figure 4.2 Accuracy and Repeatability Error of Robot Manipulator Speeds 47
Figure 4.3 Lifting Payloads Carried by Robot Manipulator 48
Figure 4.4 Accuracy and Repeatability Error of Lifting Payloads Carried 49
by Robot Manipulator
Figure 4.5 Repeatability Errors of Robot Manipulator Speeds 51
Figure 4.6 Repeatability Errors of Lifting Payloads Carried by Robot 52
Manipulator
List of Tables
Page
Table 3.1 Data Collection for Robot Manipulator's Speeds 40
Table 3.2 Data Collection for Lifting Payloads Carried by Robot 41
Manipulator
Table 4.1 Results of Robot Manipulator Speeds 44
Table 4.2 Results of Lifting Payloads Carried by Robot Manipulator 44
Table 4.3 Repeatability Error of Robot Manipulator Speeds 50
Table 4.4 Repeatability Error of Lifting Payloads Carried by Robot 50
Manipulator
CHAPTER 1
INTRODUCTION
1.1 OVERVIEW OF INDUSTRIAL ROBOT
An industrial robot has been described by the International Organization for Standardization (ISO) as follows: A machine formed by mechanism including several degrees of freedom, often having the appearance of one or several arms ending in a wrist capable of handling a tool, a workpiece, or an inspection device. In particular, its control unit must use a memorizing device and it may sometimes use sensing or adaptation appliances to take into account environment and circumstances. These multipurpose machines are generally designed to carry out a repetitive
function and can be adapted to other operations [5].
An industrial robot as a programmable multifunctional manipulator and designed to move materials, parts, tools, or other device by means of variable programmed motions is able to perform repetitive variety of tasks more quickly, cheaply, and accurately than humans. There are several hundred types and models of industrial robots and available in a wide ranges of shapes, sizes, speeds, load
capacities, and other characteristics. They are classify by their intended applications
Performance Study of Repeatability of Robot Manipulator Introduction
1.2 ROBOT COMPONENTS
The functions of robot components and their capabilities can be observed to the flexibility and capability of diverse movements of human arm, wrist, hand, and
fingers in reaching for and grabbing an object from a shelf or in using hand tool. Most complex robot can be broken into four basic components. The basic components of robot are a manipulator, end effector which is part of the manipulator, power supply, and controller.
From end-effectors Ext commands Ext feedback Controller Manipulator A--- 4 T Power supply To end-effectors
Figure 1.1 Basic of Robot's Components [5]
1.2.1 MANIPULATOR
End-effectors
Manipulator is a mechanical unit that provides motions (trajectories) to reach a point in space which having a specific set of coordinates in a specific orientation. The inspiration for the design of a manipulator is the human arm. It consists of
segments jointed together with axes capable of motion in various directions.
Performance Study of Repeatability of Robot Manipulator Introduction
A robot's movements may be classified into two general categories: arm and body (shoulder and elbow) motions, and wrist motions. The individual joint motions associated with these two categories are referred to as degree of freedom (D. O. F). Each axis is equal to one degree of freedom. There are four, five, six and even seven degree of freedom robots.
1.2.2 END EFFECTOR
The end of the wrist in a robot is equipped with an end effector The end effector or end end-of-arm tooling is a special device or fixture attached to the robot's arm been designed to mimic the function and structure of the human hand. It may be equipped with any of the following depends on types of operations:
i. Grippers, vacuum cups, electromagnets for material handling
ii. Spray guns for painting
iii. Attachments for spot and arc welding and arc cutting
iv. Power tools such as drills
v. Measuring instruments such as dial indicators
The selection of an appropriate end effector for a specific application depends on several factors such as the payload, environment, reliability, and the cost.
Performance Study of Repeatability of Robot Manipulator Introduction
1.2.3 CONTROLLER
The controller known as control system is a communication and information- processing system that gives commands for the movements of the robot. It is brain of the robot which is responsible stores data to initiates, terminates, and coordinates the motions and sequences of a robot. It interfaces with the computers and other equipment such as manufacturing cell and assembly systems.
1.2.4 POWER SUPPLY
Each motion of the manipulator is controlled and regulated by independent actuators that use an electrical, a pneumatics or a hydraulic power supply. Each source of energy and each type of motor has its own characteristics, advantages and limitations.
1.3 REPEATABILITY
Repeatability is the ability of the robot to reposition itself to a position to
which it was previously commanded or taught. Or in other word is a measurement of
the deviation between the programmed point and the return point under identical conditions of load and velocity [ 11 ]. The figure 1.2 illustrates the simple example of
repeatability. From the figure 1.2, the manipulator is programmed begin the sequence
by moving its end effector from nest (rest) to point A (programmed point). Then, the
manipulator is transverses from point A to point A' (reference point) through
Performance Study of Repeatability of Robot Manipulator Introduction
sequences of preplanned paths 1,2 and 3. The manipulator is reposition to a position of point A along the preplanned paths 4,5, and 6. The point of manipulator achieves at point A for the second times is called return point. The different between the programmed point and return point is measured and determined as repeatability error. The movement from point A to point A' and back to point A is called as one cycle.
z
1
3
A
A'
Figure 1.2 Repeatability
Repeatability can exist into two terms: long-term and short-term. Long-term repeatability is concern for robot applications requiring the same identical tasks to be performed over several months. For the applications where the robot is frequently reprogrammed for new tasks, only short-term repeatability involved. Short-term repeatability is influenced most by temperature changes with the control and the environment, as well as by transient conditions between shutdown and start-up of the system.
Performance Study gf'Repeatability of Robot Manipulator Introduction
1.4 AIMS AND OBJECTIVES
The main aim of this thesis is to study the performance of repeatability of robot manipulator. The areas concerns are the effects of robot manipulator speeds and lifting payloads carried by robot manipulator to the performance of repeatability.
This thesis involves the development of repeatability's method; robot's programming process using DENFORD Virtual Reality Robot software which integrated to the real robot Mitsubishi Micro Robot MELFA RV-MI and teach pendant box; and measurement of the repeatability of robot manipulator.
Performance Study of Repeatability of Robot Manipulator Literature Review
CHAPTER 2
LITERATURE REVIEW
2.1 BASIC TERMINOLOGY AND CONCEPT
2.1.1 ROBOT CONFIGURATIONS
The motions of arm and body vary depending upon their mechanical design.
Majority of robots possess five distinct design configurations:
i. Rectangular
ii. Cylindrical
iii. Spherical
iv. Jointed-Arm
v. SCARA (Selective Compliance Assembly Robot Arm)
The Rectangular configuration or also known Cartesian coordinated
configuration uses three perpendicular slides to construct the x, y, and z axes. The
first coordinate, x represents left and right motion; the second, y describes forward and backward motion; the third, z generally uses to depict up-and-down motion as
shown in figure 2.1. Through this configuration, equal increments of motion can be
achieved in all axes by using identical actuators. But, the motion of each axis is
limited to one direction and makes it independent of other two. By moving the three
Performance Study ofRepeatabi/ity of Robot Manipulator Literature Reviex
slides relative to one another, the robot is capable of operating within a rectangular work envelope.
:ý -ý
Figure 2.1 Rectangular Configuration [3]
The Cylindrical configuration has two linear motions and one rotary motion. The first coordinate describes the angle, 0 of base rotation; the second corresponds to a radial or R in-out motion at whatever angles the robot is positioned; the final coordinate corresponds to the up-down or z position as shown in figure 2.2. By this type of configuration, the robot is capable of retrieving a cylindrical work envelope.
Figure 2.2 Cylindrical Configuration [3]
Performance Study of Repeatability of Robot Manipulator Lawrunuv Rcr/cu
The Spherical configuration reaches any point in space through one linear and two angular motions. The first motion, 0 corresponds to a base rotation about a vertical axis; the second motion, ß corresponds to an elbow rotation; the third motion, R corresponds to a radial translation as in figure 2.3. The two directions can point the robot in any direction and permit the third motion to go directly to a specified point. By these various joints, the robot is capable of operating within a spherical envelope. ß ý fi -""--- ý' . -t t- __- ` ilL
Figure 2.3 Spherical Configuration [3]
The Jointed-Arm configuration consists of three rotary motions to reach any
point in space. It is similar to the human arm. The first rotation, 0 is about the base; the second rotation, a is about the shoulder in a horizontal axis; the final, ß is a rotation of the elbow which about a horizontal axis. The elbow axis is positioned in space is determined by the base and shoulder rotations. This type of configuration, shown in figure 2.4 can move at high speeds in various directions and has a greater variety of angles of approach to a given point. Its work envelope is of irregular shape.
Performance Studv of Repeatability of Robot Manipulator Literature Reviex 4 ý~ 1r., /ý . LI r` i iý , / /
: ý,
_ýýýýiýýý,
t; -r
ýý-
_-1 r -ý
cl, z_rFigure 2.4 Jointed-Arm Configuration [3]
While, the SCARA configuration generally reaches any point in space through one linear motion and two rotary motions. The first rotary motion, 0 is about the base; the second motion, p corresponds to the elbow about its vertical axis; and the third motion, z corresponds to the vertical up-down axis. Figure 2.5 illustrates the SCARA configuration. This type of configuration is most versatile configuration and provides a larger work envelope than the other configurations.
a
_i_=-
---ý--1a
.,
r". - ý _- =ý_ lJ r! ýý Mý"~`"1 ý_-"ý t----' _- -: --- ý- ---_Figure 2.5 SCARA Configuration [3]