Material Intelligence of Animal Whiskers

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Research Overview

Natural Embodied Touch

Finger-Surface Contact Mechanics in Diverse Moisture Conditions

Perceptual Integration of Contact Force Components During Fingertip Sliding

Material Intelligence of Animal Whiskers

Artificial Touch Sensing and Processing

Giving Touch to Soft Robot Fingertips Using Vision, Audio and Machine Learning

Capturing and Recognizing Multimodal Surface Interactions

Multimodal Puncture Detection for Urgent Percutaneous Therapies

Haptic Actuation

Quantifying the Quality of Haptic Interfaces

Shape-Changing Haptic Interfaces

Generating Clear Vibrotactile Cues with Magnets Embedded in a Soft Finger Sheath

Salient Full-Fingertip Haptic Feedback Enabled by Wearable Electrohydraulic Actuation

Cutaneous Electrohydraulic (CUTE) Wearable Devices for Pleasant Broad-Bandwidth Haptic Cues

Modeling Finger-Touchscreen Contact during Electrovibration

Perception of Ultrasonic Friction Pulses

CAPT Motor: A Two-Phase Ironless Motor Structure

Immersive Teleoperation

4D Intraoperative Surgical Perception: Anatomical Shape Reconstruction from Multiple Viewpoints

Visual-Inertial Force Estimation in Robotic Surgery

Enhancing Robotic Surgical Training

AiroTouch: Naturalistic Vibrotactile Feedback for Large-Scale Telerobotic Assembly

Optimization-Based Whole-Arm Teleoperation for Natural Human-Robot Interaction

Human-Robot Interaction

Enhancing HRI through Responsive Multimodal Feedback

Haptic Empathetic Robot Animal (HERA)

How does HuggieBot compare to a human hugging partner?

HuggieBot: Evolution of an Interactive Hugging Robot with Visual and Haptic Perception

Human Movement

Reconstructing Sign-Language Movements from Images and Bioimpedance Measurements

Advancing Gait-Retraining Techniques

Multimodal Sensing Reveals the Dynamics of Time-Constrained Teamwork

Previous HI Projects

Finger-Surface Contact Mechanics in Diverse Moisture Conditions

Computational Modeling of Finger-Surface Contact

Perceptual Integration of Contact Force Components During Tactile Stimulation

Dynamic Models and Wearable Tactile Devices for the Fingertips

Novel Designs and Rendering Algorithms for Fingertip Haptic Devices

Dimensional Reduction from 3D to 1D for Realistic Vibration Rendering

Prendo: Analyzing Human Grasping Strategies for Visually Occluded Objects

Learning Upper-Limb Exercises from Demonstrations

Minimally Invasive Surgical Training with Multimodal Feedback and Automatic Skill Evaluation

Efficient Large-Area Tactile Sensing for Robot Skin

Haptic Feedback and Autonomous Reflexes for Upper-limb Prostheses

Gait Retraining

Modeling Hand Deformations During Contact

Intraoperative AR Assistance for Robot-Assisted Minimally Invasive Surgery

Immersive VR for Phantom Limb Pain

Visual and Haptic Perception of Real Surfaces

Haptipedia

Gait Propulsion Trainer

TouchTable: A Musical Interface with Haptic Feedback for DJs

Exercise Games with Baxter

Intuitive Social-Physical Robots for Exercise

How Should Robots Hug?

Hierarchical Structure for Learning from Demonstration

Fabrication of HuggieBot 2.0: A More Huggable Robot

Learning Haptic Adjectives from Tactile Data

Feeling With Your Eyes: Visual-Haptic Surface Interaction

S-BAN

General Tactile Sensor Model

Insight: a Haptic Sensor Powered by Vision and Machine Learning

Haptic Intelligence Members Publications

Material Intelligence of Animal Whiskers

Animals have evolved diverse keratin-based structures that extend, expand, or augment their sense of touch, often with unique geometry, porosity, and/or stiffness arrangements that have never before been characterized. How do these morphology and material shifts affect touch sensing during interactions with the animal's environment? In collaboration with external and internal scientists, the Materials CSF, and the Medical Systems CSF, we are investigating a wide array of keratin-based structures, from cat fur and elephant whiskers to the rictal bristles of birds, with morphology, mechanics, and modeling approaches to connect our material findings with the tunability of touch.

Feathers help birds fly, fur keeps mammals warm, and whiskers help facilitate sensing. While these functions are quite specific, the form of these structures (feathers, fur, and whiskers) are all composed of keratin. We are taking inspiration from one particular animal structure, whiskers, to understand how this keratin building block can help facilitate sensing in animals. A wide range of terrestrial and aquatic mammal species use these whiskers as tactile sensory organs emerging from the skin for environmental monitoring tasks such as detecting unseen obstacles or perceiving wind direction. Most research focuses on understanding the complex whisker structures' geometry or their neuromechanics, studying the mechanoreceptors in the skin connected to the elongated whisker, which is assumed to be homogeneous.

We seek to understand how variations in stiffness, porosity, and geometry can impact the transmission of vibrations through biological composites such as whiskers, body hairs, skin, and feathers. We are working to combine material science, medical imaging, and biophysics with mechanical engineering modeling to determine how materials play a role in animal touch. Interestingly, the haptic interactions of these keratin-based structures bear significant resemblance to tool-mediated surface interactions by humans, as haptic vibrations travel from the contact through the whisker or the stylus to sensitive skin tissue in both cases. Thus, our experience with human touch can sometimes facilitate insights about animal touch.

This research project involves collaborations with Michael Brecht (Humboldt University of Berlin), Lena V. Kaufmann (Humboldt University of Berlin), Felicitas Predel (Max Planck Institute for Solid State Research), Vesna Srot (Max Planck Institute for Solid State Research), and Peter A. van Aken (Max Planck Institute for Solid State Research).

Members

Haptic Intelligence

Andrew K. Schulz

Research Scientist

Haptic Intelligence, Materials

Svetlana Griego

Research Engineer

Materials

Hilda David

Technical Staff

Haptic Intelligence, Materials

Deepti Philip

Research Engineer

Medical Systems

Jelena Zinnanti

Head of Medical Systems CSF

Medical Systems

Devin Sheehan

Research Technician

Robotic Materials

Lawrence Smith

Postdoctoral Researcher

Materials

Gunther Richter

Head of Materials CSF

Haptic Intelligence

Giulia Ballardini

Research Scientist

Haptic Intelligence, Robotic Materials

Natalia Sanchez-Tamayo

Doctoral Researcher

Haptic Intelligence

Katherine J. Kuchenbecker

Director

Publications

Haptic Intelligence Miscellaneous Adapting a High-Fidelity Simulation of Human Skin for Comparative Touch Sensing Schulz, A., Serhat, G., Kuchenbecker, K. J. Extended abstract (1 page) presented at the American Society of Biomechanics Annual Meeting (ASB), Madison, USA, August 2024 (Published) BibTeX

Haptic Intelligence Miscellaneous Adapting a High-Fidelity Simulation of Human Skin for Comparative Touch Sensing in the Elephant Trunk Schulz, A., Serhat, G., Kuchenbecker, K. J. 64(Supplement_1):S458-S459, Abstract presented at the Society for Integrative and Comparative Biology Annual Meeting (SICB), Seattle, USA, January 2024 (Published)

Abstract ›

Skin is a complex biological composite consisting of layers with distinct mechanical properties, morphologies, and mechanosensory capabilities. This work seeks to expand the comparative biomechanics field to comparative haptics, analyzing elephant trunk touch by redesigning a previously published human finger-pad model with morphological parameters measured from an elephant trunk. The dorsal surface of the elephant trunk has a thick, wrinkled epidermis covered with whiskers at the distal tip and deep folds at the proximal base. We hypothesize that this thick dorsal skin protects the trunk from mechanical damage but significantly dulls its tactile sensing ability. To facilitate safe and dexterous motion, the distributed dorsal whiskers might serve as pre-touch antennae, transmitting an amplified version of impending contact to the mechanoreceptors beneath the elephant's armor. We tested these hypotheses by simulating soft tissue deformation through high-fidelity finite element analyses involving representative skin layers and whiskers, modeled based on frozen African elephant trunk (Loxodonta africana) morphology. For a typical contact force, quintupling the stratum corneum thickness to match dorsal trunk skin reduces the von Mises stress communicated to the dermis by 18%. However, adding a whisker offsets this dulled sensing, as hypothesized, amplifying the stress by more than 15 at the same location. We hope this work will motivate further investigations of mammalian touch using approaches and models from the ample literature on human touch.

DOI BibTeX

Haptic Intelligence Materials Miscellaneous Whiskers That Don’t Whisk: Unique Structure From the Absence of Actuation in Elephant Whiskers Schulz, A., Kaufmann, L., Brecht, M., Richter, G., Kuchenbecker, K. J. 64(Supplement_1):S459, Abstract presented at the Society for Integrative and Comparative Biology Annual Meeting (SICB), Seattle, USA, January 2024 (Published)

Abstract ›

Whiskers are so named because these hairs often actuate circularly, whisking, via collagen wrapping at the root of the hair follicle to increase their sensing volumes. Elephant trunks are a unique case study for whiskers, as the dorsal and lateral sections of the elephant proboscis have scattered sensory hairs that lack individual actuation. We hypothesize that the actuation limitations of these non-whisking whiskers led to anisotropic morphology and non-homogeneous composition to meet the animal's sensory needs. To test these hypotheses, we examined trunk whiskers from a 35-year-old female African savannah elephant (Loxodonta africana). Whisker morphology was evaluated through micro-CT and polarized light microscopy. The whiskers from the distal tip of the trunk were found to be axially asymmetric, with an ovular cross-section at the root, shifting to a near-square cross-section at the point. Nanoindentation and additional microscopy revealed that elephant whiskers have a composition unlike any other mammalian hair ever studied: we recorded an elastic modulus of 3 GPa at the root and 0.05 GPa at the point of a single 4-cm-long whisker. This work challenges the assumption that hairs have circular cross-sections and isotropic mechanical properties. With such striking differences compared to other mammals, including the mouse (Mus musculus), rat (Rattus norvegicus), and cat (Felis catus), we conclude that whisker morphology and composition play distinct and complementary roles in elephant trunk mechanosensing.

DOI BibTeX