The Design ofHigh Performance Mechatronics

R SAcoustics & Mechatronics

www.rmsmechatronics.nl

Mice BV

www.micebv.nl www.mechatronics-academy.nl

mechatronicsacademy

brainport

www.tudelft.nl www.tuwien.ac.at

The Design ofHigh Performance

MechatronicsHigh-Tech Functionality by

Multidisciplinary System Integration

2nd revised edition

Robert Munnig SchmidtGeorg SchitterAdrian RankersJan van Eijk

Delft University Press

© 2014 The authors and IOS Press. All rights reserved.

ISBN 978-1-61499-367-4 (print)ISBN 978-1-61499-368-1 (online)doi:10.3233/978-1-61499-368-1-i

2nd revised edition, 2014

Published by IOS Press under the imprint Delft University Press

IOS Press BVNieuwe Hemweg 6b1013 BG AmsterdamThe Netherlandstel: +31-20-688 3355fax: +31-20-687 0019email: info@iospress.nlwww.iospress.nl

LEGAL NOTICEThe publisher is not responsible for the use which might be made of thefollowing information.

PRINTED IN THE NETHERLANDS

Contents

Preface xixMotivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xixComments to the Second Edition . . . . . . . . . . . . . . . . . . xxiAcknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . xxiiSummary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxiii

1 Mechatronics in the Dutch High-Tech Industry 11.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 Historical Background . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.2.1 Video Long-Play Disk (VLP) . . . . . . . . . . . . . . . . . 31.2.1.1 Signal Encoding and Read-Out Principle . . . 41.2.1.2 Compact Disc and Digital Optical Recording . 6

1.2.2 Silicon Repeater . . . . . . . . . . . . . . . . . . . . . . . . 91.2.2.1 IC Manufacturing Process . . . . . . . . . . . . 101.2.2.2 Highly Accurate Waferstage . . . . . . . . . . . 13

1.2.3 Impact of Mechatronics . . . . . . . . . . . . . . . . . . . . 161.3 Definition and International Positioning . . . . . . . . . . . . . 17

1.3.1 Different Views on Mechatronics . . . . . . . . . . . . . . 181.3.1.1 Main Targeted Application . . . . . . . . . . . . 181.3.1.2 Focus on Precision-Controlled Motion . . . . . 20

1.4 Systems Engineering and Design . . . . . . . . . . . . . . . . . . 221.4.1 Systems Engineering Methodology . . . . . . . . . . . . 22

1.4.1.1 Definitions and V-Model . . . . . . . . . . . . . 231.4.1.2 Product Creation Process . . . . . . . . . . . . . 271.4.1.3 Requirement Budgeting . . . . . . . . . . . . . . 291.4.1.4 Roadmapping . . . . . . . . . . . . . . . . . . . . 30

1.4.2 Design Methodology . . . . . . . . . . . . . . . . . . . . . . 321.4.2.1 Concurrent Engineering . . . . . . . . . . . . . 331.4.2.2 Modular Design and Platforms . . . . . . . . . 35

v

vi Contents

2 Applied Physics in Mechatronic Systems 392.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 392.2 Mechanics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

2.2.1 Coordinate Systems . . . . . . . . . . . . . . . . . . . . . . 402.2.1.1 Cartesian Coordinate System . . . . . . . . . . 412.2.1.2 Generalised Coordinate System . . . . . . . . . 412.2.1.3 Modal coordinate system . . . . . . . . . . . . . 42

2.2.2 Force and Motion . . . . . . . . . . . . . . . . . . . . . . . . 432.2.2.1 Galilei and Newton’s Laws of Motion . . . . . 442.2.2.2 Hooke’s Law of Elasticity . . . . . . . . . . . . . 462.2.2.3 Lagrange Equations of Motion . . . . . . . . . 48

2.3 Electricity and Magnetism . . . . . . . . . . . . . . . . . . . . . . 502.3.1 Electric Field . . . . . . . . . . . . . . . . . . . . . . . . . . 51

2.3.1.1 Potential Difference and Capacitance . . . . . 522.3.1.2 Electric Field in an Electric Element . . . . . 542.3.1.3 Electric current . . . . . . . . . . . . . . . . . . . 55

2.3.2 Magnetism and the Maxwell Equations . . . . . . . . . 562.3.3 Voltage and Power . . . . . . . . . . . . . . . . . . . . . . . 60

2.3.3.1 Voltage Source . . . . . . . . . . . . . . . . . . . . 602.3.3.2 Electric Power . . . . . . . . . . . . . . . . . . . . 622.3.3.3 Ohm’s Law . . . . . . . . . . . . . . . . . . . . . . 642.3.3.4 Practical Values and Summary . . . . . . . . . 65

2.4 Signal Theory and Wave Propagation . . . . . . . . . . . . . . . 662.4.1 The Concept of Frequency . . . . . . . . . . . . . . . . . . 66

2.4.1.1 Random Signals or Noise . . . . . . . . . . . . . 702.4.1.2 Power of Alternating Signals . . . . . . . . . . 70

2.4.2 Representation in the Complex Plane . . . . . . . . . . . 722.4.3 Energy Propagation in Waves . . . . . . . . . . . . . . . . 75

2.4.3.1 Mechanical Waves . . . . . . . . . . . . . . . . . 772.4.3.2 Wave Equation . . . . . . . . . . . . . . . . . . . 782.4.3.3 Electromagnetic Waves . . . . . . . . . . . . . . 822.4.3.4 Reflection of Waves . . . . . . . . . . . . . . . . . 832.4.3.5 Standing Waves . . . . . . . . . . . . . . . . . . . 85

2.4.4 Fourier Decomposition of Alternating Signals . . . . . . 882.4.4.1 Fourier in the Frequency Domain . . . . . . . 902.4.4.2 Triangle Waveform . . . . . . . . . . . . . . . . . 902.4.4.3 Sawtooth Waveform . . . . . . . . . . . . . . . . 922.4.4.4 Square Waveform . . . . . . . . . . . . . . . . . . 932.4.4.5 Non-Continuous Alternating Signals . . . . . 94

2.5 Dynamic System analysis . . . . . . . . . . . . . . . . . . . . . . . 100

Contents vii

2.5.1 Time Domain Related Responses . . . . . . . . . . . . . . 1002.5.1.1 Step Response . . . . . . . . . . . . . . . . . . . . 1012.5.1.2 Impulse Response . . . . . . . . . . . . . . . . . 102

2.5.2 Frequency Response . . . . . . . . . . . . . . . . . . . . . . 1042.5.2.1 Laplace and Fourier Transform . . . . . . . . . 1052.5.2.2 Poles and Zeros . . . . . . . . . . . . . . . . . . . 1062.5.2.3 Frequency Response Function . . . . . . . . . . 1072.5.2.4 Domain Notation of Dynamic Functions . . . 1082.5.2.5 Bode Plot . . . . . . . . . . . . . . . . . . . . . . . 1092.5.2.6 Nyquist Plot . . . . . . . . . . . . . . . . . . . . . 1132.5.2.7 Limitation to LTI Systems . . . . . . . . . . . . 115

3 Dynamics of Motion Systems 117Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1173.1 Stiffness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

3.1.1 Importance of Stiffness for Precision . . . . . . . . . . . 1193.1.2 Active Stiffness . . . . . . . . . . . . . . . . . . . . . . . . . 123

3.2 Mass-Spring Systems with Damping . . . . . . . . . . . . . . . . 1263.2.1 Dynamic Compliance . . . . . . . . . . . . . . . . . . . . . 126

3.2.1.1 Compliance of a Spring . . . . . . . . . . . . . . 1273.2.1.2 Compliance of a Damper . . . . . . . . . . . . . 1283.2.1.3 Compliance of a Body . . . . . . . . . . . . . . . 1283.2.1.4 Dynamic Stiffness . . . . . . . . . . . . . . . . . 1293.2.1.5 Lumping the Dynamic Elements . . . . . . . . 1293.2.1.6 Transfer Function of Compliance . . . . . . . . 133

3.2.2 Effects of Damping . . . . . . . . . . . . . . . . . . . . . . . 1393.2.2.1 Damped Resonance and Aperiodic Damping . 1403.2.2.2 Poles and Critical Damping . . . . . . . . . . . 1413.2.2.3 Quality-Factor Q and Energy in Resonance . 147

3.2.3 Transmissibility . . . . . . . . . . . . . . . . . . . . . . . . 1523.2.4 Two-Body Mass-Spring System . . . . . . . . . . . . . . . 156

3.2.4.1 Analytical Description . . . . . . . . . . . . . . . 1573.2.4.2 Multiplicative Expression . . . . . . . . . . . . 1583.2.4.3 Effect of Different Mass Ratios . . . . . . . . . 159

3.3 Modal Decomposition . . . . . . . . . . . . . . . . . . . . . . . . . 1643.3.1 Eigenmodes of Two-Body Mass-Spring System . . . . . 1653.3.2 Adding Damping to Eigenmodes . . . . . . . . . . . . . . 172

3.3.2.1 High levels of damping . . . . . . . . . . . . . . 1733.3.3 Theory of Modal Decomposition . . . . . . . . . . . . . . 174

3.3.3.1 Multi Degree of Freedom Equation of Motion 175

viii Contents

3.3.3.2 Eigenvalues and Eigenvectors . . . . . . . . . . 1753.3.3.3 Modal Coordinates . . . . . . . . . . . . . . . . . 1773.3.3.4 Resulting Transfer Function . . . . . . . . . . . 178

3.3.4 Graphical Representation of Mode Shapes . . . . . . . . 1803.3.4.1 Traditional Representation . . . . . . . . . . . 1813.3.4.2 Lever Representation . . . . . . . . . . . . . . . 1813.3.4.3 General System . . . . . . . . . . . . . . . . . . . 1833.3.4.4 User-Defined Physical DOF . . . . . . . . . . . 184

3.3.5 Physical Meaning of Modal Parameters . . . . . . . . . . 1873.3.5.1 Two-Body Mass-Spring System . . . . . . . . . 1883.3.5.2 Planar Flexibly Guided System . . . . . . . . . 193

3.3.6 A Pragmatic View on Sensitivity Analysis . . . . . . . . 1963.3.6.1 Example of Two Body Mass-Spring System . 1983.3.6.2 Example of Slightly Damped Resonance . . . 200

3.3.7 Suspension and Rigid-Body Modes . . . . . . . . . . . . . 2023.3.7.1 Non-Zero Rigid-Body Eigenfrequency . . . . . 205

3.4 Mechanical Frequency Response . . . . . . . . . . . . . . . . . . 2063.4.1 Multiple eigenmodes . . . . . . . . . . . . . . . . . . . . . 2063.4.2 Characteristic Frequency Responses . . . . . . . . . . . 208

3.4.2.1 Frequency Response Type I . . . . . . . . . . . 2123.4.2.2 Frequency Response Type II . . . . . . . . . . . 2133.4.2.3 Frequency Response Type III . . . . . . . . . . 2153.4.2.4 Frequency Response Type IV . . . . . . . . . . 216

3.4.3 Example Systems with Type I/II/IV Response . . . . . . 2183.4.3.1 Planar Moving Body on Compliant Spring . . 2183.4.3.2 H-drive Waferstage . . . . . . . . . . . . . . . . . 224

3.5 Summary on Dynamics . . . . . . . . . . . . . . . . . . . . . . . . 226

4 Motion Control 229Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2294.1 A Walk around the Control Loop . . . . . . . . . . . . . . . . . . 230

4.1.1 Poles and Zeros . . . . . . . . . . . . . . . . . . . . . . . . . 2324.1.1.1 Controlling Unstable Mechanical Systems . . 2324.1.1.2 Creating Instability by Active Control . . . . . 2334.1.1.3 The Zeros . . . . . . . . . . . . . . . . . . . . . . . 234

4.1.2 Properties of Feedforward Control . . . . . . . . . . . . . 2364.1.3 Properties of Feedback Control . . . . . . . . . . . . . . . 238

4.2 Feedforward Control . . . . . . . . . . . . . . . . . . . . . . . . . . 2414.2.1 Model Based Open-Loop Control . . . . . . . . . . . . . . 2414.2.2 Input Shaping . . . . . . . . . . . . . . . . . . . . . . . . . 245

Contents ix

4.2.3 Adaptive Feedforward Control . . . . . . . . . . . . . . . 2474.3 PID Feedback Control . . . . . . . . . . . . . . . . . . . . . . . . . 248

4.3.1 PD-Control of a Compact-Disc Player . . . . . . . . . . . 2494.3.1.1 Proportional Feedback . . . . . . . . . . . . . . 2504.3.1.2 Proportional-Differential Feedback . . . . . . . 2534.3.1.3 Limiting the Differentiating Action . . . . . . 256

4.3.2 Sensitivity Functions of Feedback Control . . . . . . . . 2604.3.2.1 Real Feedback Error Sensitivity . . . . . . . . 263

4.3.3 Stability and Robustness in Feedback Control . . . . . 2644.3.4 PID-Control of a Mass-Spring System . . . . . . . . . . 269

4.3.4.1 P-Control . . . . . . . . . . . . . . . . . . . . . . . 2714.3.4.2 D-Control . . . . . . . . . . . . . . . . . . . . . . . 2714.3.4.3 I-Control . . . . . . . . . . . . . . . . . . . . . . . 2724.3.4.4 Inclusion of one Resonating Eigenmode . . . . 278

4.3.5 General Guidelines for PID-control . . . . . . . . . . . . 2794.3.6 PID-Control of More Complex Systems . . . . . . . . . . 280

4.3.6.1 PID-Control of a Magnetic Bearing . . . . . . . 2804.3.6.2 Including Resonating Eigenmodes . . . . . . . 2864.3.6.3 “Optimal” PID-Control . . . . . . . . . . . . . . 2944.3.6.4 Open-Loop and Closed-Loop . . . . . . . . . . . 295

4.4 Digital Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2964.4.1 Continuous Time versus Discrete Time . . . . . . . . . . 2964.4.2 Sampling of Continuous Signals . . . . . . . . . . . . . . 2994.4.3 Digital number representation . . . . . . . . . . . . . . . 3004.4.4 Digital Filter Theory . . . . . . . . . . . . . . . . . . . . . 302

4.4.4.1 Z-Transform and Difference Equations . . . . 3024.4.4.2 Finite Impulse Response (FIR) Filter . . . . . 3044.4.4.3 Infinite Impulse Response (IIR) Filter . . . . . 3074.4.4.4 From Continuous to Discrete-Time Filters . . 310

4.5 State-Space Control Representation . . . . . . . . . . . . . . . . 3114.5.1 State-Space in Relation to Motion Control . . . . . . . . 312

4.5.1.1 Mechanical Dynamic System in State-Space . 3144.5.1.2 PID-Control Feedback in State-Space . . . . . 318

4.5.2 State Feedback . . . . . . . . . . . . . . . . . . . . . . . . . 3204.5.2.1 System Identification . . . . . . . . . . . . . . . 3224.5.2.2 State Estimation . . . . . . . . . . . . . . . . . . 3234.5.2.3 Additional Remarks on State-Space Control . 325

4.6 Limitations of Linear Feedback Control . . . . . . . . . . . . . . 3274.7 Conclusions on Motion Control . . . . . . . . . . . . . . . . . . . 332

x Contents

5 Electromechanic actuators 3335.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3335.2 Electromagnetics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335

5.2.1 History on Magnetism . . . . . . . . . . . . . . . . . . . . 3355.2.2 Magnetism from Electric Current . . . . . . . . . . . . . 3365.2.3 Hopkinson’s Law . . . . . . . . . . . . . . . . . . . . . . . . 340

5.2.3.1 Practical Aspects of Hopkinson’s Law . . . . . 3425.2.3.2 Magnetic Energy . . . . . . . . . . . . . . . . . . 342

5.2.4 Ferromagnetic Materials . . . . . . . . . . . . . . . . . . . 3445.2.4.1 Coil with Ferromagnetic Yoke . . . . . . . . . . 3455.2.4.2 Magnetisation Curve . . . . . . . . . . . . . . . 3465.2.4.3 Permanent Magnets . . . . . . . . . . . . . . . . 347

5.2.5 Creating a Magnetic Field in an Air-Gap . . . . . . . . . 3515.2.5.1 Optimal Use of Permanent Magnet Material 3555.2.5.2 Flat Magnets Reduce Fringing Flux . . . . . . 3565.2.5.3 Low Cost Loudspeaker Magnet . . . . . . . . . 357

5.3 Lorentz Actuator . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3585.3.1 Lorentz Force . . . . . . . . . . . . . . . . . . . . . . . . . . 3585.3.2 Improving the Force of a Lorentz Actuator . . . . . . . . 3625.3.3 The Moving-Coil Loudspeaker Actuator . . . . . . . . . 3635.3.4 Position Dependency of the Lorentz Force . . . . . . . . 364

5.3.4.1 Over-Hung and Under-Hung Coil . . . . . . . . 3645.3.5 Electronic Commutation . . . . . . . . . . . . . . . . . . . 366

5.3.5.1 Three-Phase Electronic Control . . . . . . . . . 3685.3.6 Figure of Merit of a Lorentz Actuator . . . . . . . . . . . 369

5.4 Variable Reluctance Actuation . . . . . . . . . . . . . . . . . . . . 3725.4.1 Reluctance Force in Lorentz Actuator . . . . . . . . . . . 372

5.4.1.1 Eddy-Current Ring . . . . . . . . . . . . . . . . . 3735.4.1.2 Ironless Stator . . . . . . . . . . . . . . . . . . . 374

5.4.2 Analytical Derivation of Reluctance Force . . . . . . . . 3755.4.3 Variable Reluctance Actuator. . . . . . . . . . . . . . . . . 380

5.4.3.1 Electromagnetic Relay . . . . . . . . . . . . . . . 3825.4.3.2 Magnetic Attraction Force . . . . . . . . . . . . 383

5.4.4 Permanent Magnet Biased Reluctance Actuator . . . . 3855.4.4.1 Double Variable Reluctance Actuator . . . . . 3855.4.4.2 Constant Common Flux . . . . . . . . . . . . . . 3875.4.4.3 Combining two Sources of Magnetic Flux . . . 3885.4.4.4 Hybrid Force Calculation . . . . . . . . . . . . . 3915.4.4.5 Magnetic Bearings . . . . . . . . . . . . . . . . . 393

5.4.5 Active Linearisation of the Reluctance Force . . . . . . 394

Contents xi

5.5 Application of Electromagnetic Actuators . . . . . . . . . . . . . 3965.5.1 Electrical Interface Properties . . . . . . . . . . . . . . . 396

5.5.1.1 Dynamic Effects of Self-Inductance . . . . . . 3965.5.1.2 Limitation of the “Jerk” . . . . . . . . . . . . . . 3995.5.1.3 Electromagnetic Damping . . . . . . . . . . . . 400

5.5.2 Comparison of the Actuation Principles . . . . . . . . . 4035.5.2.1 Standard Coil Dimension for Comparison . . 4035.5.2.2 Force of the Lorentz Actuator . . . . . . . . . . 4065.5.2.3 Force of the Reluctance Actuator . . . . . . . . 4065.5.2.4 Force of the Hybrid Actuator . . . . . . . . . . . 4075.5.2.5 Dynamic Differences . . . . . . . . . . . . . . . . 4075.5.2.6 Moving Mass . . . . . . . . . . . . . . . . . . . . . 408

5.6 Intermezzo: Electric Transformers . . . . . . . . . . . . . . . . . 4105.6.1 Ideal Transformer . . . . . . . . . . . . . . . . . . . . . . . 4115.6.2 Real Transformer . . . . . . . . . . . . . . . . . . . . . . . 413

5.7 Piezoelectric Actuators . . . . . . . . . . . . . . . . . . . . . . . . 4155.7.1 Piezoelectricity . . . . . . . . . . . . . . . . . . . . . . . . . 415

5.7.1.1 Poling . . . . . . . . . . . . . . . . . . . . . . . . . 4165.7.1.2 Tapping the Bound Charge by Electrodes . . . 418

5.7.2 Transducer Models . . . . . . . . . . . . . . . . . . . . . . 4195.7.3 Nonlinearity of Piezoelectric Actuators . . . . . . . . . . 422

5.7.3.1 Creep . . . . . . . . . . . . . . . . . . . . . . . . . 4225.7.3.2 Hysteresis . . . . . . . . . . . . . . . . . . . . . . 4235.7.3.3 Aging . . . . . . . . . . . . . . . . . . . . . . . . . 425

5.7.4 Mechanical Considerations . . . . . . . . . . . . . . . . . 4255.7.4.1 piezoelectric Stiffness . . . . . . . . . . . . . . . 4265.7.4.2 Actuator Types . . . . . . . . . . . . . . . . . . . 4265.7.4.3 Actuator Integration . . . . . . . . . . . . . . . . 4285.7.4.4 Mechanical Amplification . . . . . . . . . . . . . 4295.7.4.5 Multiple Motion Directions by Stacking . . . . 430

5.7.5 Electrical Considerations . . . . . . . . . . . . . . . . . . 4325.7.5.1 Charge vs. Voltage Control . . . . . . . . . . . . 4325.7.5.2 Self-Sensing Actuation . . . . . . . . . . . . . . 433

6 Analogue electronics in mechatronic systems 4376.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4376.2 Passive Linear Electronics . . . . . . . . . . . . . . . . . . . . . . 439

6.2.1 Network Theory and Laws . . . . . . . . . . . . . . . . . . 4396.2.1.1 Voltage Source . . . . . . . . . . . . . . . . . . . . 4396.2.1.2 Current Source . . . . . . . . . . . . . . . . . . . 440

xii Contents

6.2.1.3 Theorem of Norton and Thevenin . . . . . . . . 4426.2.1.4 Kirchhoff’s Laws . . . . . . . . . . . . . . . . . . 4436.2.1.5 Impedances in Series or Parallel . . . . . . . . 4436.2.1.6 Voltage Divider . . . . . . . . . . . . . . . . . . . 4446.2.1.7 Maximum Power of a Real Voltage Source . . 446

6.2.2 Impedances in Electronic Circuits . . . . . . . . . . . . . 4486.2.2.1 Resistors . . . . . . . . . . . . . . . . . . . . . . . 4486.2.2.2 Capacitors . . . . . . . . . . . . . . . . . . . . . . 4506.2.2.3 Inductors . . . . . . . . . . . . . . . . . . . . . . . 455

6.2.3 Passive Filters . . . . . . . . . . . . . . . . . . . . . . . . . 4586.2.3.1 Passive First-Order RC-Filters . . . . . . . . . 4586.2.3.2 Passive Higher-Order RC-Filters . . . . . . . . 4616.2.3.3 Passive LCR-Filters . . . . . . . . . . . . . . . . 463

6.2.4 Mechanical-Electrical Dynamic Analogy . . . . . . . . . 4696.3 Semiconductors and Active Electronics . . . . . . . . . . . . . . 473

6.3.1 Basic Discrete Semiconductors . . . . . . . . . . . . . . . 4746.3.1.1 Semiconductor Diode . . . . . . . . . . . . . . . 4776.3.1.2 Bipolar Transistors . . . . . . . . . . . . . . . . 4806.3.1.3 MOSFET . . . . . . . . . . . . . . . . . . . . . . . 4836.3.1.4 Other Discrete Semiconductors . . . . . . . . . 485

6.3.2 Single Transistor Linear Amplifiers . . . . . . . . . . . . 4886.3.2.1 Emitter Follower . . . . . . . . . . . . . . . . . . 4886.3.2.2 Voltage Amplifier . . . . . . . . . . . . . . . . . . 4916.3.2.3 Differential Amplifier . . . . . . . . . . . . . . . 493

6.3.3 Operational Amplifier . . . . . . . . . . . . . . . . . . . . . 4966.3.3.1 Basic Operational Amplifier Design . . . . . . 4966.3.3.2 Operational Amplifier with Feedback . . . . . 498

6.3.4 Linear Amplifiers with Operational Amplifiers . . . . . 4996.3.4.1 Design Rules . . . . . . . . . . . . . . . . . . . . . 5006.3.4.2 Non-Inverting Amplifier . . . . . . . . . . . . . 5006.3.4.3 Inverting Amplifier . . . . . . . . . . . . . . . . . 5026.3.4.4 Adding and Subtracting Signals . . . . . . . . 5036.3.4.5 Transimpedance Amplifier . . . . . . . . . . . . 5066.3.4.6 Transconductance Amplifier . . . . . . . . . . . 507

6.3.5 Active Electronic Filters . . . . . . . . . . . . . . . . . . . 5116.3.5.1 Integrator and First-Order Low-Pass . . . . . 5116.3.5.2 Differentiator and First-Order High-Pass . . . 513

6.3.6 Analogue PID-Controller . . . . . . . . . . . . . . . . . . . 5156.3.6.1 PID Transfer Function . . . . . . . . . . . . . . 5166.3.6.2 PID Control Gains . . . . . . . . . . . . . . . . . 518

Contents xiii

6.3.6.3 High-Speed PID-Control . . . . . . . . . . . . . 5186.3.7 Higher-order Electronic Filters . . . . . . . . . . . . . . . 519

6.3.7.1 Second-Order Low-Pass Filter . . . . . . . . . . 5216.3.7.2 Second-Order High-Pass Filter . . . . . . . . . 5216.3.7.3 Different Types of Active Filters . . . . . . . . 522

6.3.8 Ideal and Real Operational Amplifiers . . . . . . . . . . 5246.3.8.1 Open-Loop Voltage Gain . . . . . . . . . . . . . 5246.3.8.2 Dynamic Limitations . . . . . . . . . . . . . . . 5266.3.8.3 Input Related Limitations . . . . . . . . . . . . 5316.3.8.4 Power Supply and Output Limitations . . . . 534

6.3.9 Closing Remarks on Low-Power Electronics . . . . . . . 5356.4 Power Amplifiers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 537

6.4.1 General Properties of Power Amplifiers . . . . . . . . . . 5386.4.2 Linear Power Amplifiers . . . . . . . . . . . . . . . . . . . 541

6.4.2.1 Current-Source Amplifiers . . . . . . . . . . . . 5436.4.2.2 Dynamic Loads, Four-Quadrant Operation . . 549

6.4.3 Switched-Mode Power Amplifiers . . . . . . . . . . . . . . 5516.4.3.1 First Example Amplifier . . . . . . . . . . . . . 5516.4.3.2 Power MOSFET, a Fast High-Power Switch . 5546.4.3.3 Pulse-Width Modulation . . . . . . . . . . . . . 5566.4.3.4 High-Power Output Stage . . . . . . . . . . . . 5596.4.3.5 Intermediate Conclusions and Other Issues . 5636.4.3.6 Driving the Power MOSFETs . . . . . . . . . . 5636.4.3.7 Charge Pumping . . . . . . . . . . . . . . . . . . 5656.4.3.8 Dual-Ended Configuration . . . . . . . . . . . . 5666.4.3.9 Output Filter . . . . . . . . . . . . . . . . . . . . 568

6.4.4 Resonant-Mode Power Amplifiers . . . . . . . . . . . . . 5696.4.4.1 Switching Sequence of the Output Stage . . . 5716.4.4.2 Lossless Current Sensing . . . . . . . . . . . . . 574

6.4.5 Three-Phase Amplifiers . . . . . . . . . . . . . . . . . . . . 5756.4.5.1 Concept of Three-Phase Amplifier . . . . . . . 5766.4.5.2 Three-Phase Switching Power Stages . . . . . 577

6.4.6 Some Last Remarks on Electronics . . . . . . . . . . . . 579

7 Optics in Mechatronic Systems 5817.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5817.2 Properties of Light and Light Sources . . . . . . . . . . . . . . . 583

7.2.1 Light Generation by Thermal Radiation . . . . . . . . . 5847.2.2 Photons by Electron Energy State Variation . . . . . . . 585

7.2.2.1 Light Emitting Diodes . . . . . . . . . . . . . . . 587

xiv Contents

7.2.2.2 Laser as an Ideal Light Source . . . . . . . . . 5887.2.3 Useful Power from a Light Source . . . . . . . . . . . . . 592

7.2.3.1 Radiant Emittance and Irradiance . . . . . . . 5937.2.3.2 Radiance . . . . . . . . . . . . . . . . . . . . . . . 5937.2.3.3 Etendue . . . . . . . . . . . . . . . . . . . . . . . . 596

7.3 Reflection and Refraction . . . . . . . . . . . . . . . . . . . . . . . 5977.3.1 Reflection and Refraction according to the Least Time 598

7.3.1.1 Partial Reflection and Refraction . . . . . . . . 6017.3.2 Concept of Wavefront . . . . . . . . . . . . . . . . . . . . . 602

7.3.2.1 A Wavefront is Not Real . . . . . . . . . . . . . . 6037.4 Geometric Optics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 605

7.4.1 Imaging with Refractive Lens Elements . . . . . . . . . 6057.4.1.1 Sign Conventions . . . . . . . . . . . . . . . . . . 6077.4.1.2 Real Lens Elements . . . . . . . . . . . . . . . . 6087.4.1.3 Magnification . . . . . . . . . . . . . . . . . . . . 611

7.4.2 Aberrations . . . . . . . . . . . . . . . . . . . . . . . . . . . 6137.4.2.1 Spherical Aberration . . . . . . . . . . . . . . . 6137.4.2.2 Astigmatism . . . . . . . . . . . . . . . . . . . . . 6157.4.2.3 Coma . . . . . . . . . . . . . . . . . . . . . . . . . 6177.4.2.4 Geometric and Chromatic Aberrations . . . . 617

7.4.3 Combining Multiple Optical Elements . . . . . . . . . . 6197.4.3.1 Combining Two Positive Lenses . . . . . . . . . 620

7.4.4 Aperture Stop and Pupil . . . . . . . . . . . . . . . . . . . 6237.4.5 Telecentricity . . . . . . . . . . . . . . . . . . . . . . . . . . 624

7.4.5.1 Pupil, Aperture and Lens Dimensions . . . . . 6267.4.5.2 Practical Applications and Constraints . . . . 626

7.5 Physical Optics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6287.5.1 Polarisation . . . . . . . . . . . . . . . . . . . . . . . . . . . 628

7.5.1.1 Birefringence . . . . . . . . . . . . . . . . . . . . 6307.5.2 Interference . . . . . . . . . . . . . . . . . . . . . . . . . . . 632

7.5.2.1 Fabry-Perot Interferometer . . . . . . . . . . . 6347.5.3 Diffraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 636

7.5.3.1 Amplitude gratings . . . . . . . . . . . . . . . . 6377.5.3.2 Phase Gratings . . . . . . . . . . . . . . . . . . . 6397.5.3.3 Direction of the Incoming Light . . . . . . . . . 646

7.5.4 Imaging Quality based on Diffraction . . . . . . . . . . . 6467.5.4.1 Numerical Aperture and f-Number . . . . . . . 6507.5.4.2 Depth of Focus . . . . . . . . . . . . . . . . . . . 653

7.6 Adaptive Optics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6567.6.1 Thermal Effects in Optical Imaging Systems . . . . . . 656

Contents xv

7.6.2 Correcting the Wavefront . . . . . . . . . . . . . . . . . . 6577.6.2.1 Zernike Modes . . . . . . . . . . . . . . . . . . . . 6597.6.2.2 Correcting Zernikes by Adaptive Optics . . . . 662

7.6.3 Adaptive Optics Principle of Operation . . . . . . . . . . 6647.6.3.1 Active Mirrors . . . . . . . . . . . . . . . . . . . . 666

8 Measurement in mechatronic systems 6718.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 671

8.1.1 Measurement Systems . . . . . . . . . . . . . . . . . . . . 6728.1.2 Errors in Measurement Systems, Uncertainty . . . . . 673

8.1.2.1 Ultimate Uncertainty . . . . . . . . . . . . . . . 6758.1.2.2 Uncertainty in Traceable Measurements . . . 675

8.1.3 Functional Model of a Measurement System Element 6778.2 Dynamic Error Budgeting . . . . . . . . . . . . . . . . . . . . . . 679

8.2.1 Error Statistics in Repeated Measurements . . . . . . . 6798.2.2 The Normal Distribution . . . . . . . . . . . . . . . . . . . 6808.2.3 Combining Different Error Sources . . . . . . . . . . . . 6828.2.4 Power Spectral Density and Cumulative Power . . . . . 6838.2.5 Avoid Using the Cumulative Amplitude Spectrum . . . 686

8.2.5.1 Variations in Dynamic Error Budgeting . . . . 6868.2.6 Sources of Noise and Disturbances . . . . . . . . . . . . . 687

8.2.6.1 Mechanical Noise . . . . . . . . . . . . . . . . . . 6878.2.6.2 Electronic Noise . . . . . . . . . . . . . . . . . . . 6888.2.6.3 Using Noise Data from Data-Sheets . . . . . . 690

8.3 Sensor Signal Sensitivity . . . . . . . . . . . . . . . . . . . . . . . 6918.3.1 Sensing Element . . . . . . . . . . . . . . . . . . . . . . . . 6928.3.2 Converting an Impedance into an Electric Signal . . . 693

8.3.2.1 Wheatstone Bridge . . . . . . . . . . . . . . . . . 6948.3.3 Electronic Interconnection of Sensitive Signals . . . . . 700

8.3.3.1 Magnetic Disturbances . . . . . . . . . . . . . . 7008.3.3.2 Capacitive Disturbances . . . . . . . . . . . . . 7028.3.3.3 Ground Loops . . . . . . . . . . . . . . . . . . . . 704

8.4 Signal Conditioning . . . . . . . . . . . . . . . . . . . . . . . . . . 7068.4.1 Instrumentation Amplifier . . . . . . . . . . . . . . . . . . 7068.4.2 Filtering and Modulation . . . . . . . . . . . . . . . . . . 709

8.4.2.1 AM with Square Wave Carrier . . . . . . . . . 7108.4.2.2 AM with Sinusoidal Carrier . . . . . . . . . . . 711

8.5 Signal Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7148.5.1 Schmitt Trigger . . . . . . . . . . . . . . . . . . . . . . . . 7148.5.2 Digital Representation of Measurement Data . . . . . . 715

xvi Contents

8.5.2.1 Gray Code . . . . . . . . . . . . . . . . . . . . . . 7168.5.2.2 Sampling of Analogue Values . . . . . . . . . . 7188.5.2.3 Nyquist-Shannon Theorem . . . . . . . . . . . . 7198.5.2.4 Filtering to Prevent Aliasing . . . . . . . . . . . 722

8.5.3 Analogue-to-Digital Converters . . . . . . . . . . . . . . . 7238.5.3.1 Dual-Slope ADC . . . . . . . . . . . . . . . . . . 7238.5.3.2 Successive-Approximation ADC . . . . . . . . . 7258.5.3.3 Sigma-Delta ADC . . . . . . . . . . . . . . . . . 7288.5.3.4 ADC Latency in a Feedback Loop . . . . . . . . 731

8.5.4 Connecting the Less Sensitive Elements . . . . . . . . . 7328.5.4.1 Characteristic Impedance . . . . . . . . . . . . 7328.5.4.2 Non-Galvanic Connection . . . . . . . . . . . . . 735

8.6 Short-Range Motion Sensors . . . . . . . . . . . . . . . . . . . . . 7368.6.1 Optical Sensors . . . . . . . . . . . . . . . . . . . . . . . . . 736

8.6.1.1 Position Sensitive Detectors . . . . . . . . . . . 7378.6.1.2 Optical Deflectometer . . . . . . . . . . . . . . . 740

8.6.2 Capacitive Position Sensors . . . . . . . . . . . . . . . . . 7428.6.2.1 Linearising by Differential Measurement . . . 7438.6.2.2 Accuracy Limits and Improvements . . . . . . 7448.6.2.3 Sensing to Conductive Moving Plate . . . . . . 747

8.6.3 Inductive Position Sensors . . . . . . . . . . . . . . . . . . 7488.6.3.1 Linear Variable Differential Transformer . . . 7508.6.3.2 Eddy-Current Sensors . . . . . . . . . . . . . . . 752

8.6.4 Pneumatic Proximity Sensor or Air-Gage . . . . . . . . 7538.7 Measurement of Mechanical Dynamics . . . . . . . . . . . . . . 754

8.7.1 Measurement of Force and Strain . . . . . . . . . . . . . 7548.7.1.1 Strain Gages . . . . . . . . . . . . . . . . . . . . . 7548.7.1.2 Fibre Bragg Grating Strain Measurement . . 757

8.7.2 Velocity Measurement . . . . . . . . . . . . . . . . . . . . 7598.7.2.1 Geophone . . . . . . . . . . . . . . . . . . . . . . . 760

8.7.3 Accelerometers . . . . . . . . . . . . . . . . . . . . . . . . . 7648.7.3.1 Closed-Loop Feedback Accelerometer . . . . . 7648.7.3.2 Piezoelectric Accelerometer . . . . . . . . . . . 7668.7.3.3 MEMS Accelerometer . . . . . . . . . . . . . . . 774

8.8 Optical Long-Range Incremental Position Sensors . . . . . . . 7778.8.1 Linear Optical Encoders . . . . . . . . . . . . . . . . . . . 778

8.8.1.1 Interpolation . . . . . . . . . . . . . . . . . . . . . 7828.8.1.2 Vernier Resolution Enhancement . . . . . . . . 7848.8.1.3 Interferometric Optical Encoder . . . . . . . . 7868.8.1.4 Concluding Remarks on Linear Encoders . . . 791

Contents xvii

8.8.2 Laser Interferometer Measurement Systems . . . . . . 7928.8.2.1 Homodyne Distance Interferometry . . . . . . 7938.8.2.2 Heterodyne Distance Interferometry . . . . . . 8008.8.2.3 Measurement Uncertainty . . . . . . . . . . . . 8098.8.2.4 Configurations . . . . . . . . . . . . . . . . . . . 8168.8.2.5 Multi-Axis Laser Interferometers . . . . . . . . 821

8.8.3 Mechanical Aspects . . . . . . . . . . . . . . . . . . . . . . 8228.8.3.1 Abbe Error . . . . . . . . . . . . . . . . . . . . . . 823

9 Precision Positioning in Wafer Scanners 8279.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 827

9.1.1 Waferscanner . . . . . . . . . . . . . . . . . . . . . . . . . . 8299.1.2 Requirements on Precision . . . . . . . . . . . . . . . . . 831

9.2 Dynamic Architecture . . . . . . . . . . . . . . . . . . . . . . . . . 8359.2.1 Balance Masses . . . . . . . . . . . . . . . . . . . . . . . . 8369.2.2 Vibration Isolation . . . . . . . . . . . . . . . . . . . . . . . 838

9.2.2.1 Eigendynamics of the Sensitive Parts . . . . . 8419.3 Zero-Stiffness Stage Actuation . . . . . . . . . . . . . . . . . . . . 845

9.3.1 Waferstage Actuation Concept . . . . . . . . . . . . . . . 8469.3.1.1 Waferstepper Long-Range Lorentz Actuator . 8469.3.1.2 Multi-Axis Positioning . . . . . . . . . . . . . . . 8499.3.1.3 Long- and Short-Stroke Actuation . . . . . . . 850

9.3.2 Full Magnetic Levitation . . . . . . . . . . . . . . . . . . . 8539.3.3 Acceleration Limits of Reticle Stage . . . . . . . . . . . . 854

9.4 Position Measurement . . . . . . . . . . . . . . . . . . . . . . . . . 8569.4.1 Alignment Sensor . . . . . . . . . . . . . . . . . . . . . . . 8589.4.2 Keeping the Wafer in Focus . . . . . . . . . . . . . . . . . 8609.4.3 Dual-Stage Measurement and Exposure . . . . . . . . . 8639.4.4 Long-Range Incremental Measurement System . . . . 864

9.4.4.1 Real-Time Metrology Loop . . . . . . . . . . . . 8659.5 Motion Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 868

9.5.1 Feedforward and Feedback Control . . . . . . . . . . . . 8699.5.2 The Mass Dilemma . . . . . . . . . . . . . . . . . . . . . . 871

9.6 Future Developments in IC Lithography . . . . . . . . . . . . . 872

Appendix 875References and Recommended Reading . . . . . . . . . . . . . . . . . 875Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 876Nomenclature and abbreviations . . . . . . . . . . . . . . . . . . . . . 884Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 893

Preface

Motivation to the First Edition

A world without mechatronics is almost as unthinkable as a world with-out electric light. After its origin around the second world war the namemechatronics has become known for all kind of mechanical systems wheremechanics and electronics are combined to achieve a certain function. Thecomplexity of mechatronics ranges from a simple set of electronic controlledrelay-switches to highly integrated precision motion systems. This prolifera-tion of mechatronics has been accompanied by many books, which each havebeen written with a different scope in mind depending on the specific tech-nological anchor point of the author(s) within this wide multidisciplinaryfield of engineering.This book distinguishes itself from other books in several ways. First of allit is a combination of an industrial reference book and a university textbook,due to the mixed industrial and academic background of the authors. Theindustrial reference book part is based on extensive experience in designingthe most sophisticated motion systems presently available, the stages ofwafer scanners, which are used in the semiconductor industry. The aca-demic part is based on advanced research on precision motion systems,including ultra precision metrology equipment with fast Scanning-ProbeMicroscopy and optical measurement systems with sub-nanometre accuracy.Closely related to the industrial background is the focus on high-precisionpositioning at very high velocity and acceleration levels. With this focus,the book does not include examples from other important application areaslike robotics, machining centres and vehicle mechatronics, though the the-ory is also valid for those applications. All presented material is aimed atobtaining a maximum of control of all dynamic aspects of a motion system,which is the reason for the term “High Performance” in the title.Another, more teaching related reason for writing this book next to all other

xix

xx Preface

books in the field is based on the observation that most students at theuniversity are rather well trained in applying mathematical rules for solvingpurely mathematical problems, while they often have more difficulties inthe application of these mathematics in the modelling of real mechatronicdesigns. The industrial need for well educated real engineers with boththeoretical and practical skills, combined with a healthy critical attitude tothe outcome of computer simulations, became a guiding motive to finish thetedious job of writing. The capability to swiftly switch between model andreality is one of the most important skills of a real multidisciplinary designer.This capability helps to quickly predict the approximate system behaviourin the concept phase of a design, where intuition and small calculations onthe backside of an envelope are often more valuable than computer baseddetailed calculations by means of sophisticated modelling software. It is cer-tainly true that these software tools are indispensable for further detailingand optimisation in the later phase of a design project but more attention isneeded for basic engineering expert-knowledge to cover the concept-designphase where the most important design decisions are taken.In view of these main motivations to write this book, it was also decided tofocus uniquely on the hardware part of mechatronic systems. This meansthat the important field of embedded software is not presented even thoughsoftware often serves as the actual implementation platform for modern con-trol systems. The reason for this exclusion is the intended focus of this bookon the prime functionality of a mechatronic system, without the interfacesto other systems and human operators. The logical sequence algorithm ofthe controller, together with the sampling delay, is more important for thisprime functionality than the way how this algorithm is described in C-code.When writing a book on mechatronics, the broad range of contributing disci-plines forces a limitation in the depth to which the theory on each of thesedisciplines can be treated. Where necessary for the explanation of certaineffects the presented material goes deeper, but other subjects are treated insuch a way that an overall understanding is obtained without specialised indepth knowledge of all details.Like the work of a mechatronic engineer as system designer in a team ofspecialists, this book is aimed to be a binding factor to the related spe-cialised books, rather than one that makes these other sources of knowledgeredundant.It is our sincere wish that this book serves its purpose.Robert Munnig Schmidt, Georg Schitter, Adrian Rankers and Jan van EijkJanuary 2014

Preface xxi

To the Second Edition

As many writers will agree, any book will contain errors in spite of a thor-ough check of every line. In this case most of these errors were typos andUK language issues, but gradually it became clear that also some unbalanceexisted in the chapters, mainly regarding the basic background materialon mechanics and dynamics. The book was initially mainly intended formechanical engineering students with BSc level knowledge. It appearedhowever that also students from other disciplines would follow the relatedcourses and this made us decide to add some basic mechanics in this secondedition. Further a good friend and specialist in active dynamics in theNetherlands, Adrian Rankers, made us aware of a real error in the modalanalysis of the rotating body at the end of Chapter 3 and while investigat-ing a solution, it was concluded that the part on modal analysis deserveda much deeper treatise in view of the frequent application in controlledmechatronic systems. Adrian was happy to provide the material from hisPhD thesis [70] for inclusion in this book and he carefully reviewed theentire dynamics chapter. Also several remarks of students during lecturesand examinations pointed clearly at some parts of the text that could resultin a better understanding when written in a slightly different way. And lastbut not least several readers expressed their interest in literature citationsfor reference.Summarising the following major changes are applied:

• Chapter 2 is renamed into “Applied Physics in Mechatronic Systems”.The mechanical laws of Newton and Lagrange are added, explainingcoordinate systems and the methods to derive equations of motion fromenergy and acceleration. Several illustrations are added to explainthe Fast Fourier Transform window and the Laplace plane while theMaxwell Equations are transferred from Chapter 5 to this chapter.

• Chapter 3 is extended with a large section on the theory on modaldecomposition.

• Chapter 4 is extended with an introduction in discrete-time control.

• Relevant sources and subjects for further reading like PhD theses arecited in the text and grouped in a Bibliography section.

Finally the contributing authors expressed the wish to be more clear abouttheir specific contribution. For this reason at each chapter the contributingauthors are mentioned separately.

xxii Preface

Contributions and Acknowledgements

Besides much material from our own experience, this book also includesmaterial created by many other people.Several university staff members and students have contributed to and re-viewed the material. Some are cited in the text but even then it is impossibleto mention all without forgetting some names. as example only the mostimportant students who are not cited separately are mentioned here. Thefirst is Ton de Boer, the MSc student who entered upon the impossible taskto write the rough material that started this book as lecture notes by follow-ing the lectures on Mechatronic System Design. Johan Vogel and Oscar vdVen, also from the Mechatronic System Design group at Delft Universityof Technology reviewed the first versions and helped with the physics andelectromechanics chapters, while Markus Thier from the Automation andControl Institute at Vienna University of Technology helped with the sectionon digital motion control.Our partners from industry deserve gratitude for their support, financially,in equipment or advice, by permission to use company illustrations or byreviewing the material. The three most important to mention are the Dutchhigh-tech company ASML and the metrology companies Heidenhain fromGermany and Agilent Technologies from the United States.We further thank all other companies and individuals who kindly gave per-mission to use their illustrations. Where appropriate these are separatelymentioned at the related figures or cited in the bibliography.It is true to say that this textbook is based on the knowledge of many othersas laid down in books, patents and journal articles. Several are cited in thetext but most are not, because their knowledge entered the public domainvery long ago. Still it are these giants on whose shoulders we all stand1

and who deserve our gratitude. In that respect it is worthwhile to mentionthe increasing value of Wikipedia. Besides the possibility to quickly findcertain physical and mathematical terms or derivations, it also providedinformation about small trivia like the date of birth or the full name of afamous scientist from the past.

Errata

The errata of the first and second edition are noted at a dedicated website:errata.rmsmechatronics.nl.

1Cited with a slight variation to the words of Bernard de Chartres ≈ 1115.

Preface xxiii

Summary

This book is intended for Bsc level students as an introduction to mecha-tronics, for Msc-level students who want to extend their knowledge on allaspects of advanced mechatronics and for engineers in the high-tech indus-try who want to learn more about adjacent specialisations. To accommodatethis broad approach and define the application environment, the first andlast chapter describe the waferscanners of ASML as these complex systemsare symbolic for the high level of advancement that modern mechatronicsystems have achieved.

The nine chapters are summarised as follows:

The introduction in Chapter 1 gives the context of mechatronics in theDutch high-tech industry with the historical background, some generalobservations on the international differences in approach towards mecha-tronics and the close link with “Systems Engineering”. Subjects include thedevelopment of the optical Video Long Play (VLP) disk and the wafer stepperat Philips Research Laboratories. These developments have strongly deter-mined the dominant foothold of high-precision mechatronic system designin the Netherlands and are exemplary for the specific photon-physics ori-ented approach in this country, quite different from the machining orientedapproach in most other countries. The overview on systems engineering anddesign introduces some functional design and development methodologiesthat have proved to be crucial for the success of the high-tech industry. Thesemethods are based on industrial practice where complex multidisciplinarydesigns have to be realised. Systems Engineering is a field closely relatedto mechatronics and the corresponding principles are used in structuringthe design of a mechatronic system.

Chapter 2 on the applied physics in mechatronic systems is the firstof a series of chapters on the theory that is applied in controlled motionsystems. After an introduction to some relevant items from the mechanicaldomain, like coordinate systems and the physical laws on force and motion,the chapter introduces the theory on electricity and magnetism, essentialelement in a mechatronic positioning system. This is followed by a sectionon signal theory and wave propagation. This chapter explains the reasonwhy the properties of mechatronics are so often described in the frequencydomain next to the more mechanical oriented time-related step and impulseresponses. The chapter also introduces different graphical representationsof frequency responses, which are used in several chapters of this book.

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The hard-core of a mechatronic system is still the mechanical structure thatrepresents the real hardware, which has to be fully mastered when position-ing objects in a controlled way. In most cases, the dynamic properties of thisstructure determine the achievable control performance. Expert knowledgeof this field is a prerequisite for a mechatronic designer. For that reasonChapter 3 deals with these dynamics of motion systems and mainly con-centrates on the vibrational properties of standard mechanical elementsconsisting of a multitude of springs, bodies and dampers. It includes a morein depth treatise of modal decomposition, a method to describe the dynamicresponse to external forces by means of individual vibration modes, whichallow to optimise the structural dynamics for controlled motion.

Directly related to the mechanical dynamics is the important field of mo-tion control in Chapter 4. This chapter concentrates on a thorough un-derstanding of the working principle and tuning of the still widely usedPID controllers. The practice of loop-shaping for optimising a feedbackcontroller is introduced as it is widely used. Also an introduction is givenin state-space control with direct pole placement as this method plays anincreasing role in the design of mechatronic systems. A strong emphasis isput on the physical aspects of control. It is shown that feedback control addsvirtual elements from the mechanical domain to the system, like springsand dampers together with new elements like an integrator and observer.

Electromechanic actuators and analogue electronics are two closelyrelated hardware components of a mechatronic system. Their interaction isincreasingly underestimated by system designers, because of two reasons.Firstly the field is controlled by experts in physics and electronics. Thesespecialists have a fundamentally different more abstract frame of mindthan the mostly concrete-mechanical visually oriented system designers.The second reason for underestimating these related fields is caused by theoverwhelming amount of electronics, motors and actuators, which are allaround us, giving rise to the idea that their principle is simple and masteredby many. This idea is a dangerous delusion as the difficulty in electronics isrelated to its dynamic analogue behaviour and unfortunately the number ofpeople that master analogue electronics is rather decreasing than increas-ing. It is the analogue side of electronics, dealing with measurement andactuation, that needs most of the attention of the mechatronic designer.With this purpose in mind, Chapter 5 first presents linear electrome-chanic actuators. This chapter focuses on electromagnetic actuators whilealso piezoelectric actuators are presented as these are increasingly appliedin precision mechatronic systems. This chapter will help in the selection

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process of actuation systems and creates a knowledge base for further studyon the subject. Also the relation with power-amplifier constraints, whichare presented in the following chapter, is made clear.Chapter 6 deals with analogue electronics for measurement and powerand starts at a very basic level with passive components because most me-chanical engineering students have hardly any knowledge about electronics.The introduction of the active components leads to their application in thebasic design of the operational amplifier, the most universal and widely usedanalogue electronic building block. The last section in this large chaptergives an overview of the basic design of power amplifiers, which act asthe interface between the controller and the actuators.

Optics has become a main driver of mechatronic advancement in the pastdecades. Firstly it is an application area where mechatronics are used tocontrol and correct optical properties of imaging systems and other instru-mentation. Secondly, optics are used to determine distances in a pluralityof sensors, which enables us to create measurement systems with extremeprecision. For these reasons Chapter 7 gives an introduction to optics fromthe perspective of a mechatronic designer. Starting with basic physics onoptics with sources and the duality of light, an overview of geometrical andphysical optics is presented including limiting factors for the performance ofimaging systems. The chapter concludes with an introduction on adaptiveoptics.

Chapter 8 presents the basic principles of sensors for force and dynamicposition measurements based on several physical principles includingstrain-, inductive-, capacitive- and optical sensors. The theory in this chapterwill enable the first selection of suitable sensors when designing a mecha-tronic system. Laser interferometry and encoders will also be presented asthese are most frequently applied in high precision mechatronic systems.Even though metrology in general will be shortly touched, the chapter con-centrates on measurement for control. For this reason also the principle ofdynamic error budgeting is included, a statistical method to determinethe total error in a dynamic precision system from contributions of differenterror sources.

As closure of the book Chapter 9 presents the mechatronic design for pre-cision positioning in waferscanners where all theory is applied to itsmost extreme level. This chapter includes the basic design of positioningstages, the need for and active control of vibration isolation, and the motioncontrol approach to achieve a position accuracy of less them a nanometre atspeeds of more than 1 m/s and accelerations of more than 30 m/s2.