Actuators are devices that convert electrical energy into mechanical work, traditionally used in electrical, pneumatic and hydraulic systems. As the demand for actuator technologies grows in biomedical, prosthetic and orthotic applications, there is an increasing need for complex and sophisticated products that perform efficiently also when scaled to micro and nano domains. Providing a comprehensive overview of actuators for novel applications, this excellent book: * Presents a mechatronic approach to the design, control and integration of a range of technologies covering piezoelectric actuators, shape memory actuators, electro-active polymers, magnetostrictive actuators and electro- and magnetorheological actuators. * Examines the characteristics and performance of emerging actuators upon scaling to micro and nano domains. * Assesses the relative merits of each actuator technology and outlines prospective application fields. Offering a detailed analysis on current advances in the field, this publication will appeal to practising electrical and electronics engineers developing novel actuator systems. Mechanical and automation engineers, computer scientists and researchers will also find this a useful resource.

José L. Pons, Research Manager, Instituto de Automática Industrial, Consejo Superior de Investigaciones Científicas, Carretera de Campo Real, La Poveda, Arganda del Rey, MADRID, ESPAÑA

Foreword

xi

Preface

xiii

List of Figures

xv

List of Tables

xxv

Actuators in motion control systems: mechatronics

1

(45)

What is an actuator?

2

(3)

Transducing materials as a basis for actuator design

5

(6)

Energy domains and transduction phenomena

6

(2)

Transducer basics

8

(3)

The role of the actuator in a control system: sensing, processing and acting

11

(6)

Sensing

12

(1)

Processing

12

(1)

Actuation

13

(1)

Impedance matching

14

(3)

What is mechatronics? Principles and biomimesis

17

(6)

Principles

17

(2)

Mechatronics and biomimesis

19

(4)

Concomitant actuation and sensing: smart structures

23

(4)

Figures of merit of actuator technologies

27

(6)

Dynamic performance

28

(2)

Actuator behavior upon scaling

30

(2)

Suitability for the application

32

(1)

Static performance

32

(1)

Impact of environmental parameters

33

(1)

A classification of actuator technologies

33

(3)

Semiactive versus active actuators

33

(1)

Translational versus rotational actuators

34

(1)

Input energy domain

34

(2)

Soft versus hard actuators

36

(1)

Emerging versus traditional actuator technologies

36

(2)

Scope of the book: emerging actuators

38

(1)

Other actuator technologies

39

(7)

Electrostatic actuators

39

(2)

Thermal actuators

41

(1)

Magnetic shape memory actuators

42

(4)

Piezoelectric actuators

46

(55)

Piezoelectricity and piezoelectric materials

47

(2)

Constitutive equations of piezoelectric materials

49

(2)

Resonant piezoelectric actuators

51

(16)

Basics of resonant operation of piezoelectric loads

51

(6)

Rotational ultrasonic motors

57

(8)

Linear ultrasonic motors

65

(2)

Nonresonant piezoelectric actuators

67

(5)

Bimorph actuators

67

(2)

Stack piezoelectric actuators

69

(2)

Inchworm actuators

71

(1)

Control aspects of piezoelectric motors

72

(9)

Control circuits and resonant drivers

72

(7)

Control of nonresonant actuators

79

(2)

Figures of merit of piezoelectric actuators

81

(8)

Operational characteristics

81

(4)

Scaling of piezoelectric actuators

85

(4)

Applications

89

(12)

Applications of resonant piezoelectric actuators

89

(2)

Applications of nonresonant piezoelectric actuators

91

(10)

Shape Memory Actuators (SMAs)

101

(44)

Shape memory alloys

102

(8)

The shape memory effect

103

(5)

Pseudoelasticity in SMAs

108

(2)

Design of shape memory actuators

110

(10)

Design concepts for actuation with SMAs

111

(6)

Material considerations

117

(2)

Thermal considerations

119

(1)

Control of SMAs

120

(10)

Electrical heating

120

(1)

Concomitant sensing and actuation with SMAs

121

(3)

Integration in control loops

124

(6)

Figures of merit of shape memory actuators

130

(3)

Operational ranges

130

(2)

Scaling laws for SMA actuators

132

(1)

Applications

133

(12)

Electroactive polymer actuators (EAPs)

145

(26)

Principles

146

(13)

Wet EAP actuators

146

(9)

Dry EAP actuators

155

(4)

Design issues

159

(1)

Control of EAPs

160

(3)

Figures of merit of EAPs

163

(3)

Operational characteristics

163

(2)

Scaling laws for EAPs

165

(1)

Applications

166

(5)

Magnetostrictive actuators (MSs)

171

(34)

Principles of magnetostriction

172

(6)

Historical perspective

172

(1)

Basics of magnetic properties of materials

173

(2)

Magnetostriction: constitutive equations

175

(3)

Magnetostrictive materials: giant magnetostriction

178

(3)

Positive versus negative magnetostriction: effect of the load

178

(2)

ΔY-Effect in magnetostrictive materials

180

(1)

Design of magnetostrictive actuators

181

(4)

Design for improved stroke

183

(1)

Design for linearized, push-pull operation

183

(1)

Design of electric and magnetic circuits

184

(1)

Design for selected resonance characteristics

185

(1)

Control of magnetostrictive actuators: vibration absorption

185

(12)

Active vibration suppression

186

(5)

Smart actuators and smart structures

191

(4)

Combined sensing and actuation

195

(2)

Figures of merit of MS actuators

197

(3)

Operational range

198

(1)

Scaling laws for magnetostriction

199

(1)

Applications

200

(5)

Electro- and magnetorheological actuators (ERFs, MRFs)

205

(39)

Active rheology: transducing materials

206

(7)

Basics of rheology

206

(3)

Field-responsive fluids

209

(1)

Electro- and magnetorheology

210

(3)

Mechatronic design concepts

213

(10)

Shear, flow and squeeze modes

213

(3)

Device dimensions according to specifications

216

(1)

Driving electronics for ER and MR devices

217

(4)

Design of magnetic circuits in MR devices

221

(2)

Control of ERF and MRF

223

(6)

Sky-hook vibration isolation

225

(4)

Relative vibration isolation

229

(1)

Figures of merit of ER and MR devices

229

(6)

Material aspects

229

(1)

Size and weight of ER and MR devices

230

(1)

Available dissipative force and power

230

(2)

Scaling of active rheology concepts

232

(3)

Applications

235

(9)

Summary, conclusions and outlook

244

(28)

Brief summary

244

(8)

Piezoelectric actuators

247

(1)

Shape memory alloy actuators

247

(1)

Electroactive polymer actuators

248

(1)

Magnetostrictive actuators

249

(1)

Electro- and Magnetorheological fluid actuators

249

(1)

Example applications: case studies

250

(2)

Comparative position of emerging actuators

252

(11)

Comparative analysis in terms of force

252

(1)

Comparative analysis in terms of force density

253

(1)

Comparative analysis in terms of stroke

254

(1)

Comparative analysis in terms of work density per cycle

255

(1)

Comparative analysis in terms of power density

256

(1)

Comparative analysis in terms of bandwidth

257

(1)

Relative position in the static and dynamic plane

258

(3)

Comparison in terms of scaling trends

261

(1)

Concluding remarks

262

(1)

Research trends and application trends

263

(9)

Piezoelectric actuators

264

(1)

Shape memory alloy actuators

265

(1)

Electroactive polymer actuators

266

(1)

Magnetostrictive actuators

267

(1)

Electro- and Magnetorheological fluid actuators

268

(4)

Bibliography

272

(3)

Index

275

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