Optical Fiber Sensors for the Next Generation of Rehabilitation Robotics

Optical Fiber Sensors for the Next Generation of Rehabilitation Robotics presents development concepts and applications of optical fiber sensors made of compliant materials in rehabilitation robotics. The book provides methods for the instrumentation of novel compliant devices. It presents the development, characterization and application of optical fiber sensors in robotics, ranging from conventional robots with rigid structures to novel wearable systems with soft structures, including smart textiles and intelligent structures for healthcare. Readers can look to this book for help in designing robotic structures for different applications, including problem-solving tactics in soft robotics.

This book will be a great resource for mechanical, electrical and electronics engineers and photonics and optical sensing engineers.

Preface ix

Part I

1.1 Motivation 3

1.2 Wearable robotics and assistive devices 10

1.3 Wearable sensors and monitoring devices 14

1.4 Outline of the book 18

References 21

2.1 Soft robots: definitions and (bio)medical applications 27

2.2 Soft robots for rehabilitation and functional compensation 30

2.3 Human-in-the-loop design of soft structures and healthcare systems 34

2.3.1 Human-in-the-loop systems 34

2.3.2 Human-in-the-loop applications and current trends 37

2.3.3 Human-in-the-loop design in soft wearable robots 39

2.4 Current trends and future approaches in wearable soft robots 43

References 46

3.1 Human gait 53

3.2 Gait cycle: definitions and phases 56

3.2.1 Kinematics and dynamics of human gait 57

3.3 Gait analysis systems: fixed systems and wearable sensors 58

References 61

Part II

4.1 Historical perspective 67

4.2 Light propagation in optical waveguides 69

4.3 Optical fiber properties and types 72

4.4 Passive and active components in optical fiber systems 76

4.4.1 Light sources 77

4.4.2 Photodetectors 77

4.4.3 Optical couplers 79

4.4.4 Optical circulators 80

4.4.5 Spectrometers and optical spectrum analyzers 81

4.5 Optical fiber fabrication and connection methods 83

4.5.1 Fabrication methods 84

4.5.2 Optical fiber connectorization approaches 87

References 89

5.1 Optically transparent materials 93

5.2 Viscoelasticity overview 96

5.3 Dynamic mechanical analysis in polymer optical fibers 101

5.3.1 DMA on PMMA solid core POF 103

5.3.2 Dynamic characterization of CYTOP fibers 107

5.4 Influence of optical fiber treatments on polymer properties 111

References 115

6.1 Intensity variation sensors 119

6.1.1 Macrobending sensors 120

6.1.2 Light coupling-based sensors 125

6.1.3 Multiplexed intensity variation sensors 127

6.2 Interferometers 129

6.3 Gratings-based sensors 133

6.4 Compensation techniques and cross-sensitivity mitigation in optical fiber sensors 138

References 143

Part III

7.1 Optical fiber sensors on exoskeleton’s instrumentation 151

7.2 Exoskeleton’s angle assessment applications with intensity variation sensors 152

7.2.1 Case study: active lower limb orthosis for rehabilitation

(ALLOR) 156

7.2.2 Case study: modular exoskeleton 157

Gratings 160

7.4 Interaction forces and microclimate assessment with intensity variation sensors 166

References 172

8.1 Optical fiber sensors for kinematic parameters assessment 175

8.1.1 Intensity variation-based sensors for joint angle

assessment 175

8.1.2 Fiber Bragg gratings sensors with tunable filter

interrogation for joint angle assessment 178

8.2 Instrumented insole for plantar pressure distribution and ground reaction forces evaluation 183

8.2.1 Fiber Bragg grating insoles 183

8.2.2 Multiplexed intensity variation-based sensors for smart

insoles 188

8.3 Spatiotemporal parameters estimation using integrated optical fiber sensors 198

References 199

9.1 Series elastic actuators instrumentation 201

9.1.1 Torque measurement with intensity variation sensors 202

9.1.2 Torque measurement with intensity variation sensors 206

9.2 Tendon-driven actuators instrumentation 212

9.2.1 Artificial tendon instrumentation with highly flexible

optical fibers 213

References 217

Part IV

10.1 Optical fiber embedded-textiles for physiological parameters monitoring 223

10.1.1 Breath and heart rates monitoring 224

10.1.2 Body temperature assessment 232

10.2 Smart textile for multiparameter sensing and activities monitoring 234

10.3 Optical fiber-embedded smart clothing for mechanical perturbation and physical interaction detection 239

References 241

11.1 Smart walkers’ technology overview 245

11.2 Smart walker embedded sensors for physiological parameters assessment 247

11.2.1 System description 247

11.2.2 Preliminary validation 250

11.2.3 Experimental validation 252

11.3 Multiparameter quasidistributed sensing in a smart walker structure 252

11.3.1 Experimental validation 252

11.3.2 Experimental validation 256

References 260

12.1 Robotic surgery 263

12.2 Biosensors 269

12.2.1 Introduction to biosensing 269

12.2.2 Background on optical fiber biosensing working

principles 271

12.2.3 Biofunctionalization strategies for fiber immunosensors 276

12.2.4 Immunosensing applications in medical biomarkers

detection 279

References 282

13.1 Summary 287

13.2 Final remarks and outlook 290

Index 293

• Addresses optical fiber sensing solutions in wearable systems and soft robotics
• Presents developments—from foundational, to novel and future applications—of optical fiber sensors in the next generation of robotic devices
• Provides methods for the instrumentation of novel compliant devices