Multisensory Softness: Perceived Compliance from Multiple Sources of Information (Springer Series on Touch and Haptic Systems)

Offers a unique multidisciplinary overview of how humans interact with soft objects and how multiple sensory signals are used to perceive material properties, with an emphasis on object deformability. The authors describe a range of setups that have been employed to study and exploit sensory signals involved in interactions with compliant objects as well as techniques to simulate and modulate softness – including a psychophysical perspective of the field. __Multisensory Softness__ focuses on the cognitive mechanisms underlying the use of multiple sources of information in softness perception. Divided into three sections, the first __Perceptual Softness__ deals with the sensory components and computational requirements of softness perception, the second __Sensorimotor Softness__ looks at the motor components of the interaction with soft objects and the final part __Artificial Softness__ focuses on the identification of exploitable guidelines to help replicate softness in artificial environments. Series Editors’ Foreword 6 Contents 7 Contributors 9 Introduction 11 Part I Perceptual Softness 14 1 Physical Aspects of Softness Perception 15 1.1 Introduction 15 1.2 Physical Measures of Softness 15 1.3 Psychophysical Measurement of Softness Perception 17 1.3.1 Magnitude Estimation 17 1.3.2 Discrimination 18 1.3.3 Matching 20 1.3.4 Identification 21 1.4 Cues for the Perception of Softness 22 1.4.1 Visual Cues 22 1.4.2 Tactual Cues 23 1.5 Conclusions 26 References 26 2 Visual-Haptic Compliance Perception 28 2.1 Analysis of Softness as a Higher-Order Property 28 2.1.1 The Components of Stiffness Through Vision and Haptics 29 2.1.2 Multi-Modal Perception of Stiffness Components 30 2.2 Visual-Haptic Stiffness Perception 31 2.2.1 Integration of Visual and Haptic Cues in Stiffness Perception 32 2.2.2 Models of Visual-Haptic Integration in Stiffness Perception 33 2.3 Applications of Research on Visual-Haptic Stiffness Perception 35 2.4 Conclusion 39 References 39 3 Vibrotactile Sensation and Softness Perception 42 3.1 Introduction 42 3.1.1 Vibrotactile Sensory Information 43 3.2 Contact Mechanics and Softness Cues 44 3.2.1 Direct Skin Contact 45 3.2.2 Indirect Skin Contact 46 3.2.3 Transient Contact 47 3.2.4 Frictional Sliding 48 3.3 Effects of Low-Frequency Vibration on Softness 49 3.3.1 Prospective Mechanism 49 3.3.2 Low-Frequency Softness Rendering 51 3.4 Volumetric Softness 52 3.5 Conclusions 56 References 56 4 Perception and Synthesis of Sound-Generating Materials 59 4.1 Introduction 59 4.2 Perception 60 4.2.1 State of Matter 60 4.2.2 Perception of Stiff Solid Materials 62 4.2.3 Comparison of Material and Interaction Perception 70 4.2.4 Perception of Deformable Materials 71 4.2.5 Audio-haptic Perception of Materials 74 4.3 Synthesis 77 4.3.1 Modal Sound Synthesis 77 4.3.2 Impact Forces 80 4.3.3 Rendering of Materials and Hardness in Impact Sounds 81 4.3.4 Rendering of Deformable and Aggregate Objects 84 4.3.5 Rendering of Liquid Sounds 86 4.4 Conclusion 87 References 89 5 Computational Aspects of Softness Perception 95 5.1 Sensory Information About Softness 95 5.2 A Bayesian Model of Softness Perception 97 5.3 Redundancy in Softness Cues 102 5.3.1 Touch and Proprioception 103 5.3.2 Proprioception and Vision 107 5.4 Multiple Contact Points 108 5.5 Temporal Aspects of Softness Perception 110 5.6 Conclusions 114 References 114 Part II Sensorimotor Softness 117 6 Exploratory Movement Strategies in Softness Perception 118 6.1 Introduction 118 6.2 Exploratory Procedures in Softness Perception 118 6.2.1 Pressure 118 6.2.2 Tapping as an Instance of Pressure 121 6.3 Parametric Variation of Exploratory Procedures and the Influence on Softness Perception 123 6.3.1 Peak Forces 123 6.3.2 Rate of Force Change 126 6.3.3 Number of Fingers Used 127 6.4 Strategic Adjustment of Exploratory Peak Force 128 6.5 Conclusion 132 References 133 7 The Perception of the Centre of Elastic Force Fields: A Model of Integration of the Force and Position Signals 135 7.1 Introduction 135 7.2 Methods 137 7.2.1 Participants 137 7.2.2 Experimental Setup 138 7.2.3 Experimental Procedure and Stimuli 139 7.2.4 Data Analysis 140 7.3 Results 141 7.3.1 Force Rendering Accuracy 143 7.4 The Bisection Model 144 7.4.1 Initial Assumptions 144 7.4.2 Sensory Noise and Response Variability 145 7.4.3 Force Threshold and Response Bias 147 7.4.4 Model Parameters 148 7.5 General Discussion 151 References 153 8 Dynamic Combination of Movement and Force for Softness Discrimination 155 8.1 Introduction 155 8.2 Perception Model Representations 156 8.2.1 Sensorimotor Control Model 157 8.2.2 Feature Comparison 158 8.2.3 Inverse Model Verification 159 8.2.4 State Observer Model Verification 160 8.3 Model-Guided Experimental Design 161 8.3.1 Model-Guided Stimulus Selection 162 8.4 Experimental Investigations 164 8.4.1 Results 165 8.4.2 Model Predictions 166 8.4.3 Discussion 168 8.5 Implications for Telepresence Systems 170 8.6 Conclusions and Open Problems 171 References 171 9 Perception of Stiffness with Force Feedback Delay 174 9.1 Introduction 174 9.2 The Effect of Delay on Stiffness Perception 177 9.3 The Effect of Delay on Action: Motormetric Representation of Stiffness 183 9.4 Discussion 185 9.4.1 Novel Models for the Effect of Delay on Stiffness Perception 185 9.4.2 Development of Novel Solutions for Teleoperation 186 9.5 Conclusions 188 References 188 Part III Artificial Softness 193 10 Compliance Perception Using Natural and Artificial Motion Cues 194 10.1 Introduction 194 10.2 The Role of Proprioception in Human Compliance Perception 196 10.2.1 Background 196 10.2.2 Experiment: Role of Motion Cues in Compliance Perception 197 10.2.3 Summary and Implications 205 10.3 Haptic Sensory Substitution Systems for Compliance Perception 206 10.3.1 Challenges in Sensory Substitution 207 10.3.2 Haptic Stimulation 208 10.3.3 Experiment: Relaying Compliance Using Skin Stretch Feedback 212 10.3.4 Experiment: Perception of Hand Proprioception via Multiple Vibrating Elements 216 10.4 Concluding Remarks 218 References 218 11 A Fabric-Based Approach for Softness Rendering 223 11.1 Introduction 223 11.2 Taming the Complexity of Haptic Information 224 11.3 The Contact Area Spread Rate Approach for Softness Rendering 225 11.3.1 The First Discrete CASR-Based Display 226 11.4 Fabric-Based Displays 227 11.4.1 Introduction to the First FYD Prototype 227 11.4.2 Area Acquisition 228 11.4.3 Characterisation, Interpolation and Experiments 230 11.4.4 Evaluation Experiments 231 11.5 The Second Version of the FYD: The FYD-2 233 11.5.1 Mechanical Design 234 11.5.2 Experiments 235 11.5.3 Evaluation Experiments 239 11.6 Conclusions 242 References 242 12 Haptic Augmentation in Soft Tissue Interaction 245 12.1 Introduction 245 12.2 Haptic Augmented Reality 246 12.2.1 Taxonomy and Concepts 246 12.2.2 Related Work 246 12.3 Stiffness Augmentation 248 12.3.1 Rendering Hardware 249 12.3.2 Stiffness Modulation in Single-Contact Interaction 250 12.3.3 Stiffness Modulation in Two-Contact Squeezing 253 12.4 Example Application: Augmentation of Stiffer Inclusions 256 12.5 Conclusion and Discussion 259 References 260 Front Matter....Pages i-xiii Front Matter....Pages 1-1 Physical Aspects of Softness Perception....Pages 3-15 Visual-Haptic Compliance Perception....Pages 17-30 Vibrotactile Sensation and Softness Perception....Pages 31-47 Perception and Synthesis of Sound-Generating Materials....Pages 49-84 Computational Aspects of Softness Perception....Pages 85-106 Front Matter....Pages 107-107 Exploratory Movement Strategies in Softness Perception....Pages 109-125 The Perception of the Centre of Elastic Force Fields: A Model of Integration of the Force and Position Signals....Pages 127-146 Dynamic Combination of Movement and Force for Softness Discrimination....Pages 147-165 Perception of Stiffness with Force Feedback Delay....Pages 167-185 Front Matter....Pages 187-187 Compliance Perception Using Natural and Artificial Motion Cues....Pages 189-217 A Fabric-Based Approach for Softness Rendering....Pages 219-240 Haptic Augmentation in Soft Tissue Interaction....Pages 241-257