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Contents Introduction xi Acknowledgments xxxv Chapter 1 Motor and Motion Control Systems 1 Introduction 3 Merits of Electric Systems 4 Motion Control Classification 5 Closed-Loop System 5 Trapezoidal Velocity Profile 7 Closed-Loop Control Techniques 8 Open-Loop Motion Control Systems 9 Kinds of Controlled Motion 9 Motion Interpolation 10 Computer-Aided Emulation 10 Mechanical Components 11 Electronic System Components 15 Motor Selection 16 Motor Drivers (Amplifiers) 18 Feedback Sensors 19 Installation and Operation of the System 20 Servomotors, Stepper Motors, and Actuators for Motion Control 20 Permanent-Magnet DC Servomotors 21 Brush-Type PM DC Servomotors 22 Disk-Type PM DC Motors 23 Cup- or Shell-Type PM DC Motors 24 Position Sensing in Brushless Motors 29 Brushless Motor Advantages 30 Brushless DC Motor Disadvantages 31 Characteristics of Brushless Rotary Servomotors 31 Linear Servomotors 31 v For more information about this title, click here. Copyright © 2003 by The McGraw-Hill Companies, Inc. Click here for Terms of Use. vi Contents Commutation 34 Installation of Linear Motors 35 Advantages of Linear vs. Rotary Servomotors 36 Coil Assembly Heat Dissipation 37 Stepper Motors 37 Permanent-Magnet (PM) Stepper Motors 38 Variable Reluctance Stepper Motors 38 Hybrid Stepper Motors 38 Stepper Motor Applications 40 DC and AC Motor Linear Actuators 41 Stepper-Motor Based Linear Actuators 42 Servosystem Feedback Sensors 43 Rotary Encoders 43 Incremental Encoders 44 Absolute Encoders 46 Linear Encoders 47 Magnetic Encoders 48 Resolvers 49 Tachometers 51 Linear Variable Differential Transformers (LVDTs) 53 Linear Velocity Transducers (LVTs) 55 Angular Displacement Transducers (ATDs) 55 Inductosyns 57 Laser Interferometers 57 Precision Multiturn Potentiometers 59 Solenoids and Their Applications 60 Solenoids: An Economical Choice for Linear or Rotary Motion 60 Technical Considerations 62 Open-Frame Solenoids 63 C-Frame Solenoids 63 Box-Frame Solenoids 63 Tubular Solenoids 64 Rotary Solenoids 64 Rotary Actuators 66 Actuator Count 67 Debugging 67 Reliability 68 Cost 68 Chapter 2 Indirect Power Transfer Devices 69 Belts 72 Contents vii Flat Belts 73 O-Ring Belts 73 V-Belts 73 Timing Belts 75 Smoother Drive Without Gears 76 Plastic-and-Cable Chain 77 Chain 79 Ladder Chain 80 Roller Chain 80 Rack and Pinion Chain Drive 82 Timing or Silent Chain 82 Friction Drives 83 Cone Drive Needs No Gears Or Pulleys 84 Gears 85 Gear Terminology 87 Gear Dynamics Terminology 88 Gear Classification 88 Worm Gears 90 Worm Gear with Hydrostatic Engagement 90 Controlled Differential Drives 93 Twin-Motor Planetary Gears Provide Safety Plus Dual-Speed 95 Harmonic-Drive Speed Reducers 96 Advantages and Disadvantages 99 Flexible Face-Gears Make Efficient High-Reduction Drives 100 High-Speed Gearheads Improve Small Servo Performance 102 Simplify the Mounting 102 Cost-Effective Addition 104 Chapter 3 Direct Power Transfer Devices 107 Couplings 109 Methods for Coupling Rotating Shafts 110 Ten Universal Shaft Couplings 114 Hooke’s Joints 114 Constant-Velocity Couplings 115 Coupling of Parallel Shafts 117 Ten Different Splined Connections 118 Cylindrical Splines 118 Face Splines 120 Torque Limiters 121 Ten Torque-Limiters 121 One Time Use Torque Limiting 125 viii Contents Chapter 4 Wheeled Vehicle Suspensions and Drivetrains 127 Wheeled Mobility Systems 130 Why Not Springs? 130 Shifting the Center of Gravity 131 Wheel Size 134 Three-Wheeled Layouts 136 Four-Wheeled Layouts 141 All-Terrain Vehicle with Self-Righting and Pose Control 144 Six-Wheeled Layouts 150 Eight-Wheeled Layouts 155 Chapter 5 Tracked Vehicle Suspensions and Drive Trains 161 Steering Tracked Vehicles 167 Various Track Construction Methods 168 Track Shapes 171 Track Suspension Systems 174 Track System Layouts 178 One-Track Drive Train 178 Two-Tracked Drive Trains 179 Two-Tracked Drive Trains with Separate Steering Systems 180 Four-Tracked Drive Trains 181 Six-Tracked Drive Trains 184 Chapter 6 Steering History 187 Steering Basics 190 The Next Step Up 193 Chapter 7 Walkers 199 Leg Actuators 202 Leg Geometries 203 Walking Techniques 208 Wave Walking 208 Independent Leg Walking 208 Frame Walking 211 Roller-Walkers 214 Flexible Legs 214 Contents ix Chapter 8 Pipe Crawlers and Other Special Cases 217 Horizontal Crawlers 220 Vertical Crawlers 221 Traction Techniques for Vertical Pipe Crawlers 222 Wheeled Vertical Pipe Crawlers 223 Tracked Crawlers 224 Other Pipe Crawlers 224 External Pipe Vehicles 226 Snakes 226 Chapter 9 Comparing Locomotion Methods 227 What Is Mobility? 229 The Mobility System 229 Size 230 Efficiency 231 The Environment 232 Thermal 232 Ground Cover 233 Topography 233 Obstacles 234 Complexity 235 Speed and Cost 235 The Mobility Index Comparison Method 236 The Practical Method 236 Explain All This Using the Algebraic Method 237 Chapter 10 Manipulator Geometries 239 Positioning, Orienting, How Many Degrees of Freedom? 241 E-Chain 243 Slider Crank 243 Arm Geometries 245 Cartesian or Rectangular 246 Cylindrical 247 Polar or Spherical 248 The Wrist 250 Grippers 252 Passive Parallel Jaw Using Cross Tie 255 Passive Capture Joint with Three Degrees of Freedom 256 [...]...x Contents Industrial Robots Industrial Robot Advantages Trends in Industrial Robots Industrial Robot Characteristics Chapter 11 Proprioceptive and Environmental Sensing Mechanisms and Devices Industrial Limit Switches Layouts Combination Trip (Sense) and Hard Stop By-Pass Layouts Reversed Bump Bumper Geometries and Suspensions Simple Bumper Suspension Devices Three Link Planar Tension... segments of chapters and put together xi Copyright © 2003 by The McGraw-Hill Companies, Inc Click here for Terms of Use xii Introduction a unique robot While there are books describing the electric circuits used in robots, and books that teach the software and control code for robots, there are few that are focused entirely on the mechanisms and mechanical devices used in mobile robots This book intends... mobile robots by containing, in a single reference, complete graphically presented information on the mechanics of a mobile robot It is written in laymen’s language and filled with sketches so novices and those not trained in mechanical engineering can acquire some understanding of this interesting field It also includes clever schemes and mechanisms that mid-level mechanical engineers should find new and. .. with the aid of hundreds of sketches showing drive layouts and manipulator geometries and their work envelope It discusses what mobility really is and how to increase it without increasing the size of the robot, and how the shape of the robot can have a dramatic effect on its performance Interspersed throughout the book are unusual mechanisms and devices, included to entice the reader to think outside... produce a working robot, reduce the struggles and effort required to achieve that goal, and, therefore, increase the likelihood that your project will be a success Building, designing, and working with practical mobile robots requires knowledge in three major engineering fields: mechanical, electrical, and software Many books have been written on robots, some focusing on the complete robot system, others... new and useful Since mobile robots are being called on to perform more and more complex and practical tasks, and many are now carrying one or even two manipulators, this book has a section on manipulators and grippers for mobile robots It shows why a manipulator used on a robot is different in several ways from a manipulator used in industry Autonomous robots place special demands on their mobility system... references to mechanisms useful to both of the other types of robots Robot and mobile robot are used interchangeably throughout the book Autonomous, in this book, means acting completely independent of any human input Therefore, autonomous robot means a self-controlled, selfpowered, mobile vehicle that makes its own decisions based on inputs from sensors There are very few truly autonomous robots, and no... Pivot Suspension Devices to Detect Motions in All Three Planes Conclusion Index 258 259 259 261 263 270 276 277 278 279 280 282 283 284 284 285 286 287 289 291 Introduction T his book is meant to be interesting, helpful, and educational to hobbyists, students, educators, and midlevel engineers studying or designing mobile robots that do real work It is primarily focused on mechanisms and devices that relate... sensors to make decisions are labeled telerobotic or teleoperated to differentiate them from autonomous robots It is important to note that the mechanisms and mechanical devices that are shown in this book can be applied, in their appropriate category, to almost any vehicle or manipulator whether autonomous or not Another word, which gets a lot of use in the robot world, is mobility Mobility is defined... has powerful tools to aid in the design process beyond the many tricks, mechanical devices, and techniques shown in this book These tools include 3D design tools like SolidWorks and Pro-Engineer and also new ways to produce prototypes of the mechanisms themselves This is commonly called Rapid Prototyping (RP) NEW PROCESSES EXPAND CHOICES FOR RAPID PROTOTYPING New concepts in rapid prototyping (RP) . Robot Mechanisms and Mechanical Devices Illustrated Paul E. Sandin McGraw-Hill New York | Chicago | San Francisco. entirely on the mechanisms and mechanical devices used in mobile robots. This book intends to fill the gap in the literature of mobile robots by containing,