ROBOTICS

K.K. Appu Kuttan Professor NITK Surathkal Srinivas Nagar Karnataka (India)

I.K. International Publishing House Pvt. Ltd. NEW DELHI • MUMBAI • BENGALORE The author and publisher of this book have used their efforts in preparing the book titled “Robotics”. These efforts include development, research and compilation of basic theories and principles for the effectiveness of the book. The author and publisher make no warranty of any kind expressed in the documentation contained in the book. The author and publisher shall not be liable in any event for incidental or consequential damage in connection with or arising out of use of the book. This book is intended for fundamental understanding of the robotics subject to the students.

Published by I.K. International Publishing House Pvt. Ltd. S-25, Green Park Extension Uphaar Cinema Market New Delhi-110 016 (India) E-mail: [email protected]

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© 2007 I.K. International Publishing House Pvt. Ltd.

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Published by Krishan Makhijani for I.K. International Publishing House Pvt. Ltd. S-25, Green Park Extension, Uphaar Cinema Market, New Delhi-110 016. Printed by Rekha Printers Pvt. Ltd., Okhla Industrial Area, Phase II, New Delhi- 110 020. Contents

Preface ix

1. Fundamentals of Robotics 1 1.1 Historical Development of 1 1.2 Definitions of 2 1.3 Classification 4 1.4 Degree of Freedom and Degree of Motion 13 1.5 Manipulation of Robot Components 14 1.6 Joints and Symbols 15 1.7 Work Volume and Work Envelope 16 1.8 Resolution, Accuracy and Repeatability 18 1.9 Robot Configuration 20 1.10 Economic and Social Issues 27 1.11 Numerical Examples 28 Exercise 31

2 Robot Programming and Modular Components 32 2.1 Robot Programming Methods 32 2.2 Advantages and Disadvantages of Robot 35 2.3 Requirements for a Robot in an Industry 36 2.4 Specifications of Robot 36 2.5 Operational Capabilities Level of a Robot 37 2.6 Modular Robot Components 38 2.7 Wrist Mechanism 46 2.8 Numerical Examples 46 Exercise 51

3. Robot Sensors 52 3.1 Internal Sensors 53 3.2 External Sensors 59 3.3 Force Sensors 72 3.4 Thermocouples 77 vi Contents

3.5 Performance Characteristics of a Robot 79 3.6 Static Performance Characteristics 79 3.7 Dynamic Performance Characteristics 81 3.8 Standard Test Signals 82 3.9 Controllers 85 3.10 Time Response of a Second Order System 88 3.11 Characteristics of a Under Damped System 92 3.12 Steady State Response 95 3.13 Steady State Dynamic Characteristic 96 3.14 Examples for Illustration 98 Exercise 104

4. Robot Actuators 106 4.1 Hydraulic and Pneumatic Actuators 107 4.2 Electrical Actuators 115 4.3 Brushless Permanent Magnet DC Motor 124 4.4 AC Servomotor 125 4.5 Stepper Motor 125 4.6 Micro Actuators 127 4.7 Micro Gripper 129 4.8 Micro Motor 130 4.9 Drive Selection 131 4.10 Examples for Illustration 133 Exercise 138

5. Motion Conversion and Drives 140 5.1 Rotary to Rotary Motion Conversion 140 5.2 Harmonic Drives 144 5.3 Rotary to Linear Motion Conversion 147 5.4 Parts Presentation Methods 155 5.5 Robot Safety 157 5.6 Safe Guarding 162 5.7 Numerical Examples 163 Exercise 167

6. Mathematical Modeling of a Robot 169 6.1 Basics of Matrix Representation 169 6.2 Link Equations and Relationships 174 6.3. Problem with DH Presentation 193 6.4 Differential Motion and Velocities 194 6.5 Calculation of the Jacobian for a Robot 197 6.6 Jacobian for Revolute Joint 199 6.7 Trajectory Control 200 Contents vii

6.8 Numerical Examples 202 Exercise 208

7. Dynamics of a Robot 211 7.1 Stiffness Control of a Robot End Effector 212 7.2 Dynamic Equations for 227 7.3 Examples for Illustration 240 Exercise 255

8. Advanced Robot Systems 257 8.1 Heuristics Decision for Robot 258 8.2 Fuzzy Logic for Robot Control 259 8.3 Artificial Neural Network in Robotics 265 8.4 Biped Robot 274 8.5 Biomimetic Robotics 283 8.6 Robot Calibration 286

Appendix A: Laplace Transform 290

Appendix B: Pneumatic and Hydraulic Systems 293 Symbols and representation of standards 293

Appendix C: Routh Herwitz Criterion 305

References 307 Textbooks 307 Journal Papers 309

Index 313 Preface

This book was originally my lecturer notes written for Mechanical Engineering department Robotics course. With the encouragement from different professors and students, it was modified to the present form. This book is intended for senior or introductory graduates course in Robotics, as well as practising engineers who would like to learn about robotics. Although the book covers a fair amount of kinematics and dynamics of the robot, it also covers the sensors and actuators used in robotics system and development and classifications. Thus it can be used by mechanical engineers, electrical and electronic engineers, computer engineers and engineering technologists. The slow growth of the robotic industry in India is due to interdisciplinary nature of robotics itself. The field of robotics combines aspects of electrical, mechanical, computer science, mathematics and economics. There is at present a critical shortage of trained people with the cross disciplinary knowledge necessary to integrate successfully the various technologies involved in robotics application. It is the task of universities to provide such a cross-disciplinary education. The book has written primarily for the university students who may have little or no exposure to the subject of robotic. It also can be used by the students in the different engineering disciplines. Recently numbers of textbooks have appeared that provide comprehensive treatment of robotics. However, the present one provides a self-contained introduction to robotics.

Author 1 Fundamentals of Robotics

Robotics is an applied engineering science that has been referred to as a combination of machine tool technology and computer science. It includes diverse fields as machine design, control theory, micro-electronics, computer programming, , human factors and production theory. Research and development are proceeding in all of these areas to improve the way robots work or think. Advancement in technology will enlarge the scope of the industrial applications of robots. Robots are very powerful elements of today’s industry. They are capable of performing many different tasks and operations with precision and do not require common safety and comfort elements humans need. The subject of robotics covers many different areas. Robots alone are handy and useful. They are used together with other devices, peripherals and other manufacturing machines. They are generally integrated into a system, which as a whole is designed to perform a task or do an operation.

1.1 HISTORICAL DEVELOPMENT OF ROBOT

In earlier days men were thought of machines that mimic humans and their actions, which came as fiction novel. Mary Shelly in England published a novel in 1817 titled ‘Frankenstein’ which deals with the story of a scientist who wants to create a monster human, which then proceeds to raise a havoc in the local community. Karel Capek, a Czechoslovak playwright in 1922 wrote a story called “Rossunis Universal Robot” and introduced the word Robota meaning a slave worker. When Robota was translated into English, the word became Robot. The story concerns a brilliant scientist named Rossum and his son who develop a chemical substance similar to protoplasm. They use the substance to manufacture robots. Their plan is that the robots will serve humankind obediently and do all the physical labor. Among science fiction, Isaac Asimova has contributed a number of stories about robots. He is credited with coining the term ‘Robotics’. The machine, robotics 2 Robotics performs on the basis of three principles, which are known as the three according to Asimova. They are: (a) A robot should not injure a human being or life. (b) A robot should obey the orders of the master without conflicting the first law. (c) A robot should protect its own existence without conflicting first and second laws. These laws are very important for the existence of robots and even in the industry where robots are working from the safety point of view. Human interference in the robot-working environment may cause disaster for the life. In 1954 George Devol developed the first programmable robot. In 1961, US patent 2988237 was issued to George Devol for his programmed article transfer robots for Unimate Company. The first industrial robot appeared in 1962 in General Motors, USA supplied by Unimation. In 1967, Unimate introduced mark II robot to Japan for spray painting application. In 1968, an intelligent robot called Shakey was built at Stanford Research Institute (SRI) which has three rotation motions called articulated arm. In 1972, IBM developed a rectangular coordinate robot called IBM7565 is a Cartesian robot. In 1978, Unimation developed a polar robot called PUMA. Most companies that made robots in the mid 1980 no longer exist except those that made industrial robots. The companies are adapt Robotics, Stanford Robots, Funuc Robots and North America, Inc. Robots. Since 1983 onwards robotics became a very popular subject, both in industry as well as academia. Many nations started learning courses on robotics from 1983 onwards. Robotics is a technology with a future. Robots of the future will be mobile units with one or more arms, multiple sensor capabilities and the computational data processing power of today’s mainframe computer. They will be able to respond to human voice command. They will be able to receive general instructions and will translate those instructions using artificial intelligence into a specific set of actions required to carry them out. They will be able to see, hear, feel, and apply a precise measured force to the object and move under their own power. In short, future robots will have many of attributes of human beings. Getting from the present to the future, robot technology requires a lot of development through mechanical engineering, electrical engineering, computer science, industrial engineering, material technology, manufacturing system engineering and the social sciences. The purpose of this book is to explore and examine the different disciplines in engineering which constitute the technology of robots.

1.2 DEFINITIONS OF INDUSTRIAL ROBOT

Dictionary definition of robot is that a robot is a machine seemingly works like human beings. A robot should have all features like eyes, legs, hands, etc. with Fundamentals of Robotics 3 thinking capability similar to humans. The first successful application of robot manipulators generally involved some sort of material transfer. There are several different devices used for loading and unloading machines for automated assembly, welding, painting, sheet metal manufacturing, laser cutting, etc. and many are called industrial robots, although only a few are really intelligent enough to satisfy the criteria of robot. However, it is the brain of computer that gives the robot its utility and adaptability. Hence Japanese Industrial Robot Association (JIRA), Robot Institute of America (RIA) and British Robot Association (BRA) provided definitions for industrial robots. JIRA specifies five different levels of industrial robots. They are: (a) Manipulator, which are directly operated by human beings; (b) Sequence robot, which falls into further two categories, namely, fixed and variable sequence robot; (c) Playback robot, which executes fixed instructions; (d) The Numerical Control (NC) robots, which execute numerically loaded information; and (e) Intelligent robots having their own sensor based system which helps their programs to make decision in real time. The British Robot Association (BRA) defines a robot as ‘a reprogrammable device designed to both manipulate and transport parts, tools or specialized manufacturing implements through variable programmed motions for the performance of specific manufacturing task. According to the Robot Institute of America (RIA), a robot is a programmable, multifunctional manipulator designed to move material, parts, tools, or specialized devices through variable programmed motion for the performance of a variety of tasks. The key elements in the above definitions are the reprogrammable and multifunctional attributes of robots. A computer numerical control (CNC) machine tool uses offline part programming method, which can be either manual or computer aided such as APT language. During offline programming the machine remains in operation while new part program is generated. In the robot systems, it learns itself during tooling or programming stage. Robots have six degrees of freedom to translate and rotate an object. NC machines are used for a particular operation such as turning or milling operation. A robot can be used for multi-function- operation, such as pick and place, spot welding, spray painting, etc. However, NC machines are more accurate than robots since robots are made of a number of joint actuations and each joint gives errors. There are many other applications of robotics in areas where the use of humans is unpractical or undesirable. Among these are undersea and planet explorations, satellite retrieval and repair, defusing explosive devices, and working in radioactive environment. 4 Robotics

1.3 CLASSIFICATION

In general, robots are designed and meant to be controlled by a computer or similar device. The motion of the robot is controlled through a controller, i.e. under the supervision of a computer, which, itself, is running same type of program. Thus, if the program is changed, the actions of the robot will change accordingly. The intention is to have a device that can perform many different tasks and is very flexible in what it can do, without having to redesign it. Thus, the robot is designed to be able to perform any task that can be programmed simply by changing the program. The simple manipulator such as a crane cannot do this without operator running it all the time. Different countries have different standards for what they consider to be robot. The robots can be classified according to general classification, generation, intelligence, structural capabilities, applications and operational capabilities.

1.3.1 General Classification

Industrial robots used for multiple applications can be classified as manipulator robot. Manipulator robot involves working together with other pieces of automated or semi-automated equipment. These operations include loading and unloading, spot welding and spray-painting. There are three broad classes of industrial automation: (a) Fixed automation, (b) Programmable automation, and (c) Flexible automation. The fixed automation is used when the volume of production is very high and it is, therefore, appropriate to design specialized equipment to process the product. Programmable automation is used when the volume of production is relatively low and there are varieties of products to be made. In the programmable automation products are produced in batches. When one batch is completed, the equipment is reprogrammed to process the next batch. In flexible automation, different products can be made at the same time on the same manufacturing system. Manipulator robots are commonly used for programmable automation and flexible automation. Manipulator robot can be programmed to move its arm through a sequence of motion patterns over and over until reprogrammed to perform the same task. A manipulator robot that can see, feel and hear is called smart robot and to enable it to see, feel and hear sensors are used. Commonly used sensors are tactile sensors, machine vision, range finder, proximity sensors and miscellaneous sensors based on the system. Tactile sensors are devices, which indicate contact among themselves and some other solid objects. Machine vision is an important sensor technology with potential applications in many industrial operations. The capability Fundamentals of Robotics 5 of the robot to use speech synthesis to communicate information about its task and environment is widely used. Speech synthesis is a technology that exists in the present-day smart robots. Tele-operator or master-slave devices were developed during the Second World War to handle radioactive materials. The first robot essentially combined the mechanical linkages of the tele-operator with autonomy. In 1947, first electric powered tele-operator was developed. In the tele-operator, an operator can perform the task from a safe distance. The tele-operated robot is constructed in such a way that the operator has a control of manipulator by means of a slave unit. Prosthesis is an artificial device to replace a moving part of a body such as leg or hand, which works similar to the moving parts. The work is in progress at a number of research centers to develop an artificial hand with attributes similar to those of a human hand. The human hand configuration, with four articulated fingers offered by thumb is a most universal tool. It can do much more than simply holding an object. Prosthesis system articulates taking the signals from the brain, where the electrode senses the brain signals. The nervous impulses sensed by the electrode are processed electrically by a special purpose computer, which in turn controls the motion of the substructure such as limb or hand. Exoskeleton is a robot looking like external supportive structure of animal or human being. There are collections of mechanical linkages that are made to surround either human limbs or the entire human frame. They have the ability to amplify a human power. However, it is clear that they cannot act independently as such because they are not robots. In fact, when an exoskeleton device is used, the operator must exercise extreme caution, due to the increased forces and/or speeds that are possible. An example of such a device is the general electronic handyman, developed in 1970 which utilized hydraulically actuated sensors. Using this device loads up to 800 kg could be lifted by a worker. A biological type of robot carrying all capabilities as human being which is linked with one or more mechanical devices are called . Cyborg has artificial intelligence and some of the physiological functions. The design of the smart materials is a major technical challenge in the development of cyborg. Nearly all biological structures are smart materials. A remarkable example is human skin. Skin is permeable to certain substances such as water and dissolved ions. It acts as a sensor to heat, to touch and to sound. It is self-renewing. It also acts as a barrier to air from the outside. Even cyborg is in fiction stage, development of molecular motors is a breakthrough which uses the energy stored in the molecules for muscle movement. Nano scale molecular motor that carries molecular cargo through the cell by moving along nano scale track within the cell. In many respects, it is the worlds smallest type of train carrying materials of nano weights to the cell. Cybot is a cyborg which has additional calculation components for computations. Biological molecules store the information through the special character of molecules. These storage capabilities of the cybot can be improved 6 Robotics like human being. Even cyborg and cybot are in fiction stage. The future research will give nano robots of cyborg and cybot their attributes.

1.3.2 Classification According to Robot Generation

More generally industrial robots are discussed in terms of generation. At present three generations can be identified in the industry though the third generation is still largely in research state. Fourth and fifth generation robots are still in fiction stage. First generation robot can be a device that operates according to a strict and fixed sequence of events. They are also known as dumb robots, since they faithfully reproduce the programmed sequence whether the work is present or not. First generation robots cannot detect any change in the surrounding environment and therefore, they cannot modify their actions. Programming is done by altering the physical positions of limit switches, resetting stop on indexable drums, or replacing cams to alter movements. The successful use of first generation robots depends on ensuring that the correct components presented to the robot in the correct place, in the correct orientation and at the correct time. The first generation robot had no sensing or computing power, whereas the second-generation robot has sensory feedback, a reasonable high level of computing power and an explicit text of high-level language. Second generation robot is known as clever robot. Second generation robots are equipped with a range of sensors and the necessary computing power, to modify their actions in response to small detectable changes in the surrounding environment. For instance, second generation robots transfer large components from a conveyor to one bin and small components picked from the same conveyor to another bin. Second generation robots are more complex and are more expensive since they are provided with a number of sensors. Third generation robots are called intelligent robots. The third generation robots will allow decision-making and problem solving through sensory feedback processing based on artificial intelligence techniques. They will be characterized by their ability to plan, make strategic decisions and execute tasks intelligently. They are still in the research stage and their development largely depends on the parallel development of artificial intelligence software systems. Fourth generation robot has all the features of human beings. Fourth generation robot is a machine which has physical strength and intelligence similar to humans. Robot has all types of sensors to recognize the object and environment and it takes decision to perform a task as human beings. Fifth generation robot is superior to fourth generation robot and hence it is more complex. Fifth generation robot has high physical strength and intelligence than human beings. It has all professional decision-making ability for a particular Fundamentals of Robotics 7 task. The fourth and fifth generation robots are still in fiction stage, however, they have the potential to be developed into biological robots.

1.3.3 Structural Capabilities of Robot

The mechanics of a robotic manipulator can vary considerably. All the robots must be able to move a part to some point in the space. According to the structural capability robots can be classified basically as fixed robots and mobile robots. In a fixed robot the base of the robot is always fixed and it acts on open chain mechanisms. Figure 1.1 illustrates some of the fixed robots. Mobile robots use a locomotive mechanism to move around the fixed environment. Mobile robots are classified into wheel robot and walking robot. Wheel robots are called Automatic Guided Vehicles (AGVs). AGVs have built-in power system, mobility tracking devices. Wheel robots can move on smooth surface. Walking machines are robots that imitate human beings or animals by having the ability to walk on two or four legs. The most common way of defining the path of AGVs is by means of a guided- wire buried just below the surface of the floor. On the under side of the vehicle is a sensor system which detects the wire and guides the vehicle along the defined path. In more sophisticated guided systems, instructions to start/stop or change routes are communicated to each vehicle electrically over radio frequencies. Guided vehicles are able to transport materials between work cells and to load and unload the machine in the work cell. Walking machines offer greatest versatility in dealing with variety of surfaces and obstacles. However, walking machines must overcome the problem of coordinating the motion of the legs and stability problems. Since a walking machine is assumed to operate over rough terrain, they must be highly adaptive to irregularities of the terrain. There are a number of factors that must be considered in the design and control of walking machine. These factors include the number of legs, gait selection, balance, and coordination of legs. Much research work has been reported on one-legged, two-legged, four- legged and six-legged machines. Two- is known as biped robot. Figure 1.2 shows the mobile robots.

1.3.4 Classification According to Intelligence

Robot systems are usually classified as low technology and high technology groups according to their intelligence. Low technology robots do not use servo control to indicate relative positions of the joints. Their control system is intended for single motion cycles, such as pick and place of the components where each axis is normally limited to two end points. High technology robots are servo controlled systems; they accept more sophisticated sensors and programming languages. The intelligent Robotics

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