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1100 results (View BibTeX file of all listed publications)

2024

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Demonstration: OCRA - A Kinematic Retargeting Algorithm for Expressive Whole-Arm Teleoperation

Mohan, M., Kuchenbecker, K. J.

Hands-on demonstration presented at the Conference on Robot Learning (CoRL), Munich, Germany, November 2024 (misc) Accepted

Abstract
Traditional teleoperation systems focus on controlling the pose of the end-effector (task space), often neglecting the additional degrees of freedom present in human and many robotic arms. This demonstration presents the Optimization-based Customizable Retargeting Algorithm (OCRA), which was designed to map motions from one serial kinematic chain to another in real time. OCRA is versatile, accommodating any robot joint counts and segment lengths, and it can retarget motions from human arms to kinematically different serial robot arms with revolute joints both expressively and efficiently. One of OCRA's key features is its customizability, allowing the user to adjust the emphasis between hand orientation error and the configuration error of the arm's central line, which we call the arm skeleton. To evaluate the perceptual quality of the motions generated by OCRA, we conducted a video-watching study with 70 participants; the results indicated that the algorithm produces robot motions that closely resemble human movements, with a median rating of 78/100, particularly when the arm skeleton error weight and hand orientation error are balanced. In this demonstration, the presenter will wear an Xsens MVN Link and teleoperate the arms of a NAO child-size humanoid robot to highlight OCRA's ability to create intuitive and human-like whole-arm motions.

hi

Project Page [BibTex]

2024

hi Mohan, M., Kuchenbecker, K. J. Demonstration: OCRA - A Kinematic Retargeting Algorithm for Expressive Whole-Arm Teleoperation Hands-on demonstration presented at the Conference on Robot Learning (CoRL), Munich, Germany, November 2024 (misc) Accepted

Project Page [BibTex]

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Demonstration: Minsight - A Soft Vision-Based Tactile Sensor for Robotic Fingertips

Andrussow, I., Sun, H., Martius, G., Kuchenbecker, K. J.

Hands-on demonstration presented at the Conference on Robot Learning (CoRL), Munich, Germany, November 2024 (misc) Accepted

Abstract
Beyond vision and hearing, tactile sensing enhances a robot's ability to dexterously manipulate unfamiliar objects and safely interact with humans. Giving touch sensitivity to robots requires compact, robust, affordable, and efficient hardware designs, especially for high-resolution tactile sensing. We present a soft vision-based tactile sensor engineered to meet these requirements. Comparable in size to a human fingertip, Minsight uses machine learning to output high-resolution directional contact force distributions at 60 Hz. Minsight's tactile force maps enable precise sensing of fingertip contacts, which we use in this hands-on demonstration to allow a 3-DoF robot arm to physically track contact with a user's finger. While observing the colorful image captured by Minsight's internal camera, attendees can experience how its ability to detect delicate touches in all directions facilitates real-time robot interaction.

al hi ei

Project Page [BibTex]

al hi ei Andrussow, I., Sun, H., Martius, G., Kuchenbecker, K. J. Demonstration: Minsight - A Soft Vision-Based Tactile Sensor for Robotic Fingertips Hands-on demonstration presented at the Conference on Robot Learning (CoRL), Munich, Germany, November 2024 (misc) Accepted

Project Page [BibTex]

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Active Haptic Feedback for a Virtual Wrist-Anchored User Interface

Bartels, J. U., Sanchez-Tamayo, N., Sedlmair, M., Kuchenbecker, K. J.

Hands-on demonstration presented at the ACM Symposium on User Interface Software and Technology (UIST), Pittsburgh, USA, October 2024 (misc) Accepted

hi

DOI [BibTex]

hi Bartels, J. U., Sanchez-Tamayo, N., Sedlmair, M., Kuchenbecker, K. J. Active Haptic Feedback for a Virtual Wrist-Anchored User Interface Hands-on demonstration presented at the ACM Symposium on User Interface Software and Technology (UIST), Pittsburgh, USA, October 2024 (misc) Accepted

DOI [BibTex]

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Modeling Shank Tissue Properties and Quantifying Body Composition with a Wearable Actuator-Accelerometer Set

Rokhmanova, N., Martus, J., Faulkner, R., Fiene, J., Kuchenbecker, K. J.

Extended abstract (1 page) presented at the American Society of Biomechanics Annual Meeting (ASB), Madison, USA, August 2024 (misc)

hi

Project Page [BibTex]

hi Rokhmanova, N., Martus, J., Faulkner, R., Fiene, J., Kuchenbecker, K. J. Modeling Shank Tissue Properties and Quantifying Body Composition with a Wearable Actuator-Accelerometer Set Extended abstract (1 page) presented at the American Society of Biomechanics Annual Meeting (ASB), Madison, USA, August 2024 (misc)

Project Page [BibTex]

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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 (misc)

hi

[BibTex]

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

[BibTex]

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Empowering Change: The Role of Student Changemakers in Advancing Sustainability within Engineering Education

Matthew, V., Simancek, R. E., Telepo, E., Machesky, J., Willman, H., Ismail, A. B., Schulz, A. K.

Proceedings of the American Society of Engineering Education (ASEE), June 2024, Victoria Matthew and Andrew K. Schulz contributed equally to this publication. (issue) In press

hi

[BibTex]

hi Matthew, V., Simancek, R. E., Telepo, E., Machesky, J., Willman, H., Ismail, A. B., Schulz, A. K. Empowering Change: The Role of Student Changemakers in Advancing Sustainability within Engineering Education Proceedings of the American Society of Engineering Education (ASEE), June 2024, Victoria Matthew and Andrew K. Schulz contributed equally to this publication. (issue) In press

[BibTex]

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Errors in Long-Term Robotic Surgical Training

Lev, H. K., Sharon, Y., Geftler, A., Nisky, I.

Work-in-progress paper (3 pages) presented at the EuroHaptics Conference, Lille, France, June 2024 (misc)

Abstract
Robotic surgeries offer many advantages but require surgeons to master complex motor tasks over years. Most motor-control studies focus on simple tasks and span days at most. To help bridge this gap, we followed surgical residents learning complex tasks on a surgical robot over six months. Here, we focus on the task of moving a ring along a curved wire as quickly and accurately as possible. We wrote an image processing algorithm to locate the errors in the task and computed error metrics and task completion time. We found that participants decreased their completion time and number of errors over the six months, however, the percentage of error time in the task remained constant. This long-term study sheds light on the learning process of the surgeons and opens the possibility of further studying their errors with the aim of minimizing them.

hi

DOI [BibTex]

hi Lev, H. K., Sharon, Y., Geftler, A., Nisky, I. Errors in Long-Term Robotic Surgical Training Work-in-progress paper (3 pages) presented at the EuroHaptics Conference, Lille, France, June 2024 (misc)

DOI [BibTex]

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GaitGuide: A Wearable Device for Vibrotactile Motion Guidance

Rokhmanova, N., Martus, J., Faulkner, R., Fiene, J., Kuchenbecker, K. J.

Workshop paper (3 pages) presented at the ICRA Workshop on Advancing Wearable Devices and Applications Through Novel Design, Sensing, Actuation, and AI, Yokohama, Japan, May 2024 (misc)

Abstract
Wearable vibrotactile devices can provide salient sensations that attract the user's attention or guide them to change. The future integration of such feedback into medical or consumer devices would benefit from understanding how vibrotactile cues vary in amplitude and perceived strength across the heterogeneity of human skin. Here, we developed an adhesive vibrotactile device (the GaitGuide) that uses two individually mounted linear resonant actuators to deliver directional motion guidance. By measuring the mechanical vibrations of the actuators via small on-board accelerometers, we compared vibration amplitudes and perceived signal strength across 20 subjects at five signal voltages and four sites around the shank. Vibrations were consistently smallest in amplitude—but perceived to be strongest—at the site located over the tibia. We created a fourth-order linear dynamic model to capture differences in tissue properties across subjects and sites via optimized stiffness and damping parameters. The anterior site had significantly higher skin stiffness and damping; these values also correlate with subject-specific body-fat percentages. Surprisingly, our study shows that the perception of vibrotactile stimuli does not solely depend on the vibration magnitude delivered to the skin. These findings also help to explain the clinical practice of evaluating vibrotactile sensitivity over a bony prominence.

hi zwe-rob

link (url) Project Page [BibTex]

hi zwe-rob Rokhmanova, N., Martus, J., Faulkner, R., Fiene, J., Kuchenbecker, K. J. GaitGuide: A Wearable Device for Vibrotactile Motion Guidance Workshop paper (3 pages) presented at the ICRA Workshop on Advancing Wearable Devices and Applications Through Novel Design, Sensing, Actuation, and AI, Yokohama, Japan, May 2024 (misc)

link (url) Project Page [BibTex]

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Three-Dimensional Surface Reconstruction of a Soft System via Distributed Magnetic Sensing

Sundaram, V. H., Smith, L., Turin, Z., Rentschler, M. E., Welker, C. G.

Workshop paper (3 pages) presented at the ICRA Workshop on Advancing Wearable Devices and Applications Through Novel Design, Sensing, Actuation, and AI, Yokohama, Japan, May 2024 (misc)

Abstract
This study presents a new method for reconstructing continuous 3D surface deformations for a soft pneumatic actuation system using embedded magnetic sensors. A finite element analysis (FEA) model was developed to quantify the surface deformation given the magnetometer readings, with a relative error between the experimental and the simulated sensor data of 7.8%. Using the FEA simulation solutions and a basic model-based mapping, our method achieves sub-millimeter accuracy in measuring deformation from sensor data with an absolute error between the experimental and simulated sensor data of 13.5%. These results show promise for real-time adjustments to deformation, crucial in environments like prosthetic and orthotic interfaces with human limbs.

hi

[BibTex]

hi Sundaram, V. H., Smith, L., Turin, Z., Rentschler, M. E., Welker, C. G. Three-Dimensional Surface Reconstruction of a Soft System via Distributed Magnetic Sensing Workshop paper (3 pages) presented at the ICRA Workshop on Advancing Wearable Devices and Applications Through Novel Design, Sensing, Actuation, and AI, Yokohama, Japan, May 2024 (misc)

[BibTex]

{CAPT} Motor: A Strong Direct-Drive Rotary Haptic Interface
CAPT Motor: A Strong Direct-Drive Rotary Haptic Interface

Javot, B., Nguyen, V. H., Ballardini, G., Kuchenbecker, K. J.

Hands-on demonstration presented at the IEEE Haptics Symposium, Long Beach, USA, April 2024 (misc)

Abstract
We have designed and built a new motor named CAPT Motor that delivers continuous and precise torque. It is a brushless ironless motor using a Halbach-magnet ring and a planar axial Lorentz-coil array. This motor is unique as we use a two-phase design allowing for higher fill factor and geometrical accuracy of the coils, as they can all be made separately. This motor outperforms existing Halbach ring and cylinder motors with a torque constant per magnet volume of 9.94 (Nm/A)/dm3, a record in the field. The angular position of the rotor is measured by a high-resolution incremental optical encoder and tracked by a multimodal data acquisition device. The system's control firmware uses this angle measurement to calculate the two-phase motor currents needed to produce the torque commanded by the virtual environment at the rotor's position. The strength and precision of the CAPT Motor's torque and the lack of any mechanical transmission enable unusually high haptic rendering quality, indicating the promise of this new motor design.

hi

link (url) Project Page [BibTex]

hi Javot, B., Nguyen, V. H., Ballardini, G., Kuchenbecker, K. J. CAPT Motor: A Strong Direct-Drive Rotary Haptic Interface Hands-on demonstration presented at the IEEE Haptics Symposium, Long Beach, USA, April 2024 (misc)

link (url) Project Page [BibTex]

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Quantifying Haptic Quality: External Measurements Match Expert Assessments of Stiffness Rendering Across Devices

Fazlollahi, F., Seifi, H., Ballardini, G., Taghizadeh, Z., Schulz, A., MacLean, K. E., Kuchenbecker, K. J.

Work-in-progress paper (2 pages) presented at the IEEE Haptics Symposium, Long Beach, USA, April 2024 (misc)

hi

Project Page [BibTex]

hi Fazlollahi, F., Seifi, H., Ballardini, G., Taghizadeh, Z., Schulz, A., MacLean, K. E., Kuchenbecker, K. J. Quantifying Haptic Quality: External Measurements Match Expert Assessments of Stiffness Rendering Across Devices Work-in-progress paper (2 pages) presented at the IEEE Haptics Symposium, Long Beach, USA, April 2024 (misc)

Project Page [BibTex]

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Cutaneous Electrohydraulic (CUTE) Wearable Devices for Multimodal Haptic Feedback

Sanchez-Tamayo, N., Yoder, Z., Ballardini, G., Rothemund, P., Keplinger, C., Kuchenbecker, K. J.

Extended abstract (1 page) presented at the IEEE RoboSoft Workshop on Multimodal Soft Robots for Multifunctional Manipulation, Locomotion, and Human-Machine Interaction, San Diego, USA, April 2024 (misc)

hi rm

[BibTex]

hi rm Sanchez-Tamayo, N., Yoder, Z., Ballardini, G., Rothemund, P., Keplinger, C., Kuchenbecker, K. J. Cutaneous Electrohydraulic (CUTE) Wearable Devices for Multimodal Haptic Feedback Extended abstract (1 page) presented at the IEEE RoboSoft Workshop on Multimodal Soft Robots for Multifunctional Manipulation, Locomotion, and Human-Machine Interaction, San Diego, USA, April 2024 (misc)

[BibTex]

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Cutaneous Electrohydraulic Wearable Devices for Expressive and Salient Haptic Feedback

Sanchez-Tamayo, N., Yoder, Z., Ballardini, G., Rothemund, P., Keplinger, C., Kuchenbecker, K. J.

Hands-on demonstration presented at the IEEE Haptics Symposium, Long Beach, USA, April 2024 (misc)

hi rm

[BibTex]

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Language Models Can Reduce Asymmetry in Information Markets

Rahaman, N., Weiss, M., Wüthrich, M., Bengio, Y., Li, E., Pal, C., Schölkopf, B.

arXiv:2403.14443, March 2024, Published as: Redesigning Information Markets in the Era of Language Models, Conference on Language Modeling (COLM) (techreport)

Abstract
This work addresses the buyer's inspection paradox for information markets. The paradox is that buyers need to access information to determine its value, while sellers need to limit access to prevent theft. To study this, we introduce an open-source simulated digital marketplace where intelligent agents, powered by language models, buy and sell information on behalf of external participants. The central mechanism enabling this marketplace is the agents' dual capabilities: they not only have the capacity to assess the quality of privileged information but also come equipped with the ability to forget. This ability to induce amnesia allows vendors to grant temporary access to proprietary information, significantly reducing the risk of unauthorized retention while enabling agents to accurately gauge the information's relevance to specific queries or tasks. To perform well, agents must make rational decisions, strategically explore the marketplace through generated sub-queries, and synthesize answers from purchased information. Concretely, our experiments (a) uncover biases in language models leading to irrational behavior and evaluate techniques to mitigate these biases, (b) investigate how price affects demand in the context of informational goods, and (c) show that inspection and higher budgets both lead to higher quality outcomes.

ei

link (url) [BibTex]

ei Rahaman, N., Weiss, M., Wüthrich, M., Bengio, Y., Li, E., Pal, C., Schölkopf, B. Language Models Can Reduce Asymmetry in Information Markets arXiv:2403.14443, March 2024, Published as: Redesigning Information Markets in the Era of Language Models, Conference on Language Modeling (COLM) (techreport)

link (url) [BibTex]

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Koopman Spectral Analysis Uncovers the Temporal Structure of Spontaneous Neural Events

Shao, K., Xu, Y., Logothetis, N., Shen, Z., Besserve, M.

Computational and Systems Neuroscience Meeting (COSYNE), March 2024 (poster)

ei

link (url) [BibTex]

ei Shao, K., Xu, Y., Logothetis, N., Shen, Z., Besserve, M. Koopman Spectral Analysis Uncovers the Temporal Structure of Spontaneous Neural Events Computational and Systems Neuroscience Meeting (COSYNE), March 2024 (poster)

link (url) [BibTex]

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Interpreting How Large Language Models Handle Facts and Counterfactuals through Mechanistic Interpretability

Ortu, F.

University of Trieste, Italy, March 2024 (mastersthesis)

ei

[BibTex]

Elephants develop wrinkles through both form and function
Elephants develop wrinkles through both form and function

Kaufmann, L., Schulz, A., Reveyaz, N., Ritter, C., Hildebrandt, T., Brecht, M.

Society of Integrative and Comparative Biology, Seattle, USA, January 2024 (misc) Accepted

Abstract
Elephant trunks have prominent folds and wrinkles from birth, but we have little information on how wrinkle patterns differ between elephant species and how elephant trunks and their wrinkles develop. We assessed wrinkle patterns in Asian (Elephas maximus) and African savanna (Loxodonta africana) elephants. We find that adult Asian elephants have more dorsal trunk wrinkles (~126) than African elephants (~83). In both species, we find more dorsal than ventral trunk wrinkles and a closer spacing of wrinkles in the distal than in the proximal trunk. We also observed slight (10%) differences in wrinkle numbers as a function of trunk-lateralization, suggesting the wrinkle-pattern is use-dependent. MicroCT imaging revealed that the outer elephant trunk skin has a relatively constant thickness, whereas the inner skin parts are thicker between folds than in folds. In both elephant species in early fetuses the trunk shows the greatest length growth of all body parts and the ventral trunk tip develops before the dorsal trunk finger. In development, trunk wrinkles are added in two distinct phases, an early exponential phase and a later, slower phase. We suggest that wrinkles improve the ability of trunk skin to bend, and that differential flexibility requirements might explain dorsoventral, proximal-distal, left-right side, and species differences in wrinkle distribution.

hi

[BibTex]

hi Kaufmann, L., Schulz, A., Reveyaz, N., Ritter, C., Hildebrandt, T., Brecht, M. Elephants develop wrinkles through both form and function Society of Integrative and Comparative Biology, Seattle, USA, January 2024 (misc) Accepted

[BibTex]

Adapting a High-Fidelity Simulation of Human Skin for Comparative Touch Sensing in the Elephant Trunk
Adapting a High-Fidelity Simulation of Human Skin for Comparative Touch Sensing in the Elephant Trunk

Schulz, A., Serhat, G., Kuchenbecker, K. J.

Abstract presented at the Society for Integrative and Comparative Biology Annual Meeting (SICB), Seattle, USA, January 2024 (misc)

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.

hi

[BibTex]

hi Schulz, A., Serhat, G., Kuchenbecker, K. J. Adapting a High-Fidelity Simulation of Human Skin for Comparative Touch Sensing in the Elephant Trunk Abstract presented at the Society for Integrative and Comparative Biology Annual Meeting (SICB), Seattle, USA, January 2024 (misc)

[BibTex]

Simplifying the Wrinkled Complexity of Elephant Trunks using Knitted Biomimicry
Simplifying the Wrinkled Complexity of Elephant Trunks using Knitted Biomimicry

Singal, K., Schulz, A., Dimitriyev, M., Matsumoto, E.

Society of Integrative and Comparative Biology, Seattle, USA, January 2024 (misc) Accepted

Abstract
The elephant trunk skin’s unique morphology and composition result in prominent wrinkles and folds along the trunk; these features provide the trunk versatility and flexibility and contribute to the functionality of the trunk in different situations. These wrinkled and folded structures change throughout the trunk giving different functional trade-offs. The tip has skin for gripping and the proximal base has skin for protection. We attempt to capture these unique properties by manipulating the programmable nature of knitted fabrics and knit bio-inspired mimics of the wrinkles and folds. Using MicroCTs scans of the African elephant trunk tissue we look at the morphology and composition of different sites along the elephant trunk. Knitted fabrics provide a design space where one can program not only visual characteristics but directed elasticity as well. We use mechanical testing experiments to compare the likeness of the knitted mimics with actual elephant trunk skin samples – collected humanely – to test the viability of the mimics and better understand trunk properties. This work gives way to understanding wrinkled phenomenon in nature and ways we can re-create the complexities of skin using novel material methods.

hi

[BibTex]

hi Singal, K., Schulz, A., Dimitriyev, M., Matsumoto, E. Simplifying the Wrinkled Complexity of Elephant Trunks using Knitted Biomimicry Society of Integrative and Comparative Biology, Seattle, USA, January 2024 (misc) Accepted

[BibTex]

Defining Mammalian Climbing Gaits and their influence criteria including morphology and mechanics
Defining Mammalian Climbing Gaits and their influence criteria including morphology and mechanics

Shriver, C., Schulz, A., Scott, D., Elgart, J., Mendelson, J., Hu, D., Chang, Y.

Society of Integrative and Comparative Biology, Seattle, USA, January 2024 (misc) Accepted

Abstract
In comparison to terrestrial locomotion, climbing presents a couple unique challenges. First, organisms must move upwards, meaning they lack a “restoring force” to bring them back into contact with the climbing surface as they continuously overcome gravitational forces. Second, organisms must possess morphology capable of gripping the climbing surface and perform appropriate contact patterns to prevent falling. While recent studies have examined climbing via van der Waals forces and capillary adhesion, these are often limited to non-mammalian species less than 500 grams. Even amongst the studies for mammals, many are focused on primates, which take advantage of highly specialized opposable thumbs, elongated digits, and/or prehensile tails. Despite the phylogenetic diversity of mammalian climbers, basic concepts like climbing gaits are still limited to insects, primates, and robots. In this work, we attempt to translate the foundational descriptions of terrestrial gaits, e.g. horses trotting, to mammalian climbing gaits. We performed kinematics analyses to identify common mammalian climbing gaits and discerned some underlying criteria influencing these gaits. Due to the aforementioned biomechanical constraints specific to climbing, we predict non-primate, mammalian climbing gaits will all fall within and occupy a smaller subspace of the known terrestrial gaits described by Hildebrand.

hi

[BibTex]

hi Shriver, C., Schulz, A., Scott, D., Elgart, J., Mendelson, J., Hu, D., Chang, Y. Defining Mammalian Climbing Gaits and their influence criteria including morphology and mechanics Society of Integrative and Comparative Biology, Seattle, USA, January 2024 (misc) Accepted

[BibTex]

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Collagen entanglement in elephant skin gives way to strain-stiffening mechanisms

Sordilla, S., Schulz, A., Hu, D., Higgins, C.

Society of Integrative and Comparative Biology, Seattle, USA, January 2024 (misc) Accepted

Abstract
Form-function relationships often have tradeoffs: if a material is tough, it is often inflexible, and vice versa. This is particularly relevant for the elephant trunk, where the skin should be protective yet elastic. To investigate how this is achieved, we used classical histochemical staining and second harmonic generation microscopy to describe the morphology and composition of elephant trunk skin. We report structure at the macro and micro scales, from the thickness of the dermis to the interaction of 10 µm thick collagen fibers. We analyzed several sites along the length of the trunk, to compare and contrast the dorsal-ventral and proximal-distal skin morphologies and compositions. We find the dorsal skin of the elephant trunk can have keratin armor layers over 2mm thick, which is nearly 100 times the thickness of the equivalent layer in human skin. We also found that the structural support layer (the dermis) of elephant trunk contains a distribution of collagen-I (COL1) fibers in both perpendicular and parallel arrangement. The bimodal distribution of collagen is seen across all portions of the trunk, and is dissimilar from that of human skin where one orientation dominates within a body site. We hypothesize that this distribution of COL1 in the elephant trunk allows both flexibility and load-bearing capabilities. Additionally, when viewing individual fiber interaction of 10 µm thick collagen, we find the fiber crossings per unit volume are five times more common than in human skin, suggesting that the fibers are entangled. We surmise that these intriguing structures permit both flexibility and strength in the elephant trunk. The complex nature of the elephant skin may inspire the design of materials that can combine strength and flexibility.

hi

[BibTex]

hi Sordilla, S., Schulz, A., Hu, D., Higgins, C. Collagen entanglement in elephant skin gives way to strain-stiffening mechanisms Society of Integrative and Comparative Biology, Seattle, USA, January 2024 (misc) Accepted

[BibTex]

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MPI-10: Haptic-Auditory Measurements from Tool-Surface Interactions

Khojasteh, B., Shao, Y., Kuchenbecker, K. J.

Dataset published as a companion to the journal article "Robust Surface Recognition with the Maximum Mean Discrepancy: Degrading Haptic-Auditory Signals through Bandwidth and Noise" in IEEE Transactions on Haptics, January 2024 (misc)

hi

DOI Project Page [BibTex]

hi Khojasteh, B., Shao, Y., Kuchenbecker, K. J. MPI-10: Haptic-Auditory Measurements from Tool-Surface Interactions Dataset published as a companion to the journal article "Robust Surface Recognition with the Maximum Mean Discrepancy: Degrading Haptic-Auditory Signals through Bandwidth and Noise" in IEEE Transactions on Haptics, January 2024 (misc)

DOI Project Page [BibTex]

Whiskers That Don’t Whisk: Unique Structure From the Absence of Actuation in Elephant Whiskers
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.

Abstract presented at the Society for Integrative and Comparative Biology Annual Meeting (SICB), Seattle, USA, January 2024 (misc)

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.

zwe-csfm hi

[BibTex]

zwe-csfm hi Schulz, A., Kaufmann, L., Brecht, M., Richter, G., Kuchenbecker, K. J. Whiskers That Don’t Whisk: Unique Structure From the Absence of Actuation in Elephant Whiskers Abstract presented at the Society for Integrative and Comparative Biology Annual Meeting (SICB), Seattle, USA, January 2024 (misc)

[BibTex]

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Use the 4S (Signal-Safe Speckle Subtraction): Explainable Machine Learning reveals the Giant Exoplanet AF Lep b in High-Contrast Imaging Data from 2011

Bonse, M. J., Gebhard, T. D., Dannert, F. A., Absil, O., Cantalloube, F., Christiaens, V., Cugno, G., Garvin, E. O., Hayoz, J., Kasper, M., Matthews, E., Schölkopf, B., Quanz, S. P.

2024 (misc) Submitted

ei

arXiv [BibTex]

ei Bonse, M. J., Gebhard, T. D., Dannert, F. A., Absil, O., Cantalloube, F., Christiaens, V., Cugno, G., Garvin, E. O., Hayoz, J., Kasper, M., Matthews, E., Schölkopf, B., Quanz, S. P. Use the 4S (Signal-Safe Speckle Subtraction): Explainable Machine Learning reveals the Giant Exoplanet AF Lep b in High-Contrast Imaging Data from 2011 2024 (misc) Submitted

arXiv [BibTex]

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Learning a Terrain- and Robot-Aware Dynamics Model for Autonomous Mobile Robot Navigation

Achterhold, J., Guttikonda, S., Kreber, J. U., Li, H., Stueckler, J.

CoRR abs/2409.11452, 2024, Preprint submitted to Robotics and Autonomous Systems Journal. https://arxiv.org/abs/2409.11452 (techreport) Submitted

Abstract
Mobile robots should be capable of planning cost-efficient paths for autonomous navigation. Typically, the terrain and robot properties are subject to variations. For instance, properties of the terrain such as friction may vary across different locations. Also, properties of the robot may change such as payloads or wear and tear, e.g., causing changing actuator gains or joint friction. Autonomous navigation approaches should thus be able to adapt to such variations. In this article, we propose a novel approach for learning a probabilistic, terrain- and robot-aware forward dynamics model (TRADYN) which can adapt to such variations and demonstrate its use for navigation. Our learning approach extends recent advances in meta-learning forward dynamics models based on Neural Processes for mobile robot navigation. We evaluate our method in simulation for 2D navigation of a robot with uni-cycle dynamics with varying properties on terrain with spatially varying friction coefficients. In our experiments, we demonstrate that TRADYN has lower prediction error over long time horizons than model ablations which do not adapt to robot or terrain variations. We also evaluate our model for navigation planning in a model-predictive control framework and under various sources of noise. We demonstrate that our approach yields improved performance in planning control-efficient paths by taking robot and terrain properties into account.

ev

preprint [BibTex]

ev Achterhold, J., Guttikonda, S., Kreber, J. U., Li, H., Stueckler, J. Learning a Terrain- and Robot-Aware Dynamics Model for Autonomous Mobile Robot Navigation CoRR abs/2409.11452, 2024, Preprint submitted to Robotics and Autonomous Systems Journal. https://arxiv.org/abs/2409.11452 (techreport) Submitted

preprint [BibTex]

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Natural and Robust Walking using Reinforcement Learning without Demonstrations in High-Dimensional Musculoskeletal Models
2024 (misc)

Abstract
Humans excel at robust bipedal walking in complex natural environments. In each step, they adequately tune the interaction of biomechanical muscle dynamics and neuronal signals to be robust against uncertainties in ground conditions. However, it is still not fully understood how the nervous system resolves the musculoskeletal redundancy to solve the multi-objective control problem considering stability, robustness, and energy efficiency. In computer simulations, energy minimization has been shown to be a successful optimization target, reproducing natural walking with trajectory optimization or reflex-based control methods. However, these methods focus on particular motions at a time and the resulting controllers are limited when compensating for perturbations. In robotics, reinforcement learning~(RL) methods recently achieved highly stable (and efficient) locomotion on quadruped systems, but the generation of human-like walking with bipedal biomechanical models has required extensive use of expert data sets. This strong reliance on demonstrations often results in brittle policies and limits the application to new behaviors, especially considering the potential variety of movements for high-dimensional musculoskeletal models in 3D. Achieving natural locomotion with RL without sacrificing its incredible robustness might pave the way for a novel approach to studying human walking in complex natural environments. Videos: this https://sites.google.com/view/naturalwalkingrl

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link (url) [BibTex]

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A Pontryagin Perspective on Reinforcement Learning

Eberhard, O., Vernade, C., Muehlebach, M.

Max Planck Institute for Intelligent Systems, 2024 (techreport)

lds

link (url) [BibTex]

lds Eberhard, O., Vernade, C., Muehlebach, M. A Pontryagin Perspective on Reinforcement Learning Max Planck Institute for Intelligent Systems, 2024 (techreport)

link (url) [BibTex]

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Distributed Event-Based Learning via ADMM

Er, D., Trimpe, S., Muehlebach, M.

Max Planck Institute for Intelligent Systems, 2024 (techreport)

lds

link (url) [BibTex]

lds Er, D., Trimpe, S., Muehlebach, M. Distributed Event-Based Learning via ADMM Max Planck Institute for Intelligent Systems, 2024 (techreport)

link (url) [BibTex]

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Incremental Few-Shot Adaptation for Non-Prehensile Object Manipulation using Parallelizable Physics Simulators

Baumeister, F., Mack, L., Stueckler, J.

CoRR abs/2409.13228, CoRR, 2024, Submitted to IEEE International Conference on Robotics and Automation (ICRA) 2025 (techreport) Submitted

Abstract
Few-shot adaptation is an important capability for intelligent robots that perform tasks in open-world settings such as everyday environments or flexible production. In this paper, we propose a novel approach for non-prehensile manipulation which iteratively adapts a physics-based dynamics model for model-predictive control. We adapt the parameters of the model incrementally with a few examples of robot-object interactions. This is achieved by sampling-based optimization of the parameters using a parallelizable rigid-body physics simulation as dynamic world model. In turn, the optimized dynamics model can be used for model-predictive control using efficient sampling-based optimization. We evaluate our few-shot adaptation approach in several object pushing experiments in simulation and with a real robot.

ev

preprint supplemental video link (url) [BibTex]

ev Baumeister, F., Mack, L., Stueckler, J. Incremental Few-Shot Adaptation for Non-Prehensile Object Manipulation using Parallelizable Physics Simulators CoRR abs/2409.13228, CoRR, 2024, Submitted to IEEE International Conference on Robotics and Automation (ICRA) 2025 (techreport) Submitted

preprint supplemental video link (url) [BibTex]

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Discrete Fourier Transform Three-to-One (DFT321): Code

Landin, N., Romano, J. M., McMahan, W., Kuchenbecker, K. J.

MATLAB code of discrete fourier transform three-to-one (DFT321), 2024 (misc)

hi

Code Project Page [BibTex]

hi Landin, N., Romano, J. M., McMahan, W., Kuchenbecker, K. J. Discrete Fourier Transform Three-to-One (DFT321): Code MATLAB code of discrete fourier transform three-to-one (DFT321), 2024 (misc)

Code Project Page [BibTex]

2023

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Denoising Representation Learning for Causal Discovery

Sakenyte, U.

Université de Genèva, Switzerland, December 2023, external supervision (mastersthesis)

ei

[BibTex]

2023

ei Sakenyte, U. Denoising Representation Learning for Causal Discovery Université de Genèva, Switzerland, December 2023, external supervision (mastersthesis)

[BibTex]

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Navigating the Ocean of Biases: Political Bias Attribution in Language Models via Causal Structures

Jenny, D.

ETH Zurich, Switzerland, November 2023, external supervision (thesis)

ei

[BibTex]

ei Jenny, D. Navigating the Ocean of Biases: Political Bias Attribution in Language Models via Causal Structures ETH Zurich, Switzerland, November 2023, external supervision (thesis)

[BibTex]

Seeking Causal, Invariant, Structures with Kernel Mean Embeddings in Haptic-Auditory Data from Tool-Surface Interaction
Seeking Causal, Invariant, Structures with Kernel Mean Embeddings in Haptic-Auditory Data from Tool-Surface Interaction

Khojasteh, B., Shao, Y., Kuchenbecker, K. J.

Workshop paper (4 pages) presented at the IROS Workshop on Causality for Robotics: Answering the Question of Why, Detroit, USA, October 2023 (misc)

Abstract
Causal inference could give future learning robots strong generalization and scalability capabilities, which are crucial for safety, fault diagnosis and error prevention. One application area of interest consists of the haptic recognition of surfaces. We seek to understand cause and effect during physical surface interaction by examining surface and tool identity, their interplay, and other contact-irrelevant factors. To work toward elucidating the mechanism of surface encoding, we attempt to recognize surfaces from haptic-auditory data captured by previously unseen hemispherical steel tools that differ from the recording tool in diameter and mass. In this context, we leverage ideas from kernel methods to quantify surface similarity through descriptive differences in signal distributions. We find that the effect of the tool is significantly present in higher-order statistical moments of contact data: aligning the means of the distributions being compared somewhat improves recognition but does not fully separate tool identity from surface identity. Our findings shed light on salient aspects of haptic-auditory data from tool-surface interaction and highlight the challenges involved in generalizing artificial surface discrimination capabilities.

hi

Manuscript Project Page [BibTex]

hi Khojasteh, B., Shao, Y., Kuchenbecker, K. J. Seeking Causal, Invariant, Structures with Kernel Mean Embeddings in Haptic-Auditory Data from Tool-Surface Interaction Workshop paper (4 pages) presented at the IROS Workshop on Causality for Robotics: Answering the Question of Why, Detroit, USA, October 2023 (misc)

Manuscript Project Page [BibTex]

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Efficient Sampling from Differentiable Matrix Elements

Kofler, A.

Technical University of Munich, Germany, September 2023 (mastersthesis)

ei

[BibTex]

ei Kofler, A. Efficient Sampling from Differentiable Matrix Elements Technical University of Munich, Germany, September 2023 (mastersthesis)

[BibTex]

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NearContact: Accurate Human Detection using Tomographic Proximity and Contact Sensing with Cross-Modal Attention

Garrofé, G., Schoeffmann, C., Zangl, H., Kuchenbecker, K. J., Lee, H.

Extended abstract (4 pages) presented at the International Workshop on Human-Friendly Robotics (HFR), Munich, Germany, September 2023 (misc)

hi

Project Page [BibTex]

hi Garrofé, G., Schoeffmann, C., Zangl, H., Kuchenbecker, K. J., Lee, H. NearContact: Accurate Human Detection using Tomographic Proximity and Contact Sensing with Cross-Modal Attention Extended abstract (4 pages) presented at the International Workshop on Human-Friendly Robotics (HFR), Munich, Germany, September 2023 (misc)

Project Page [BibTex]

The Role of Kinematics Estimation Accuracy in Learning with Wearable Haptics
The Role of Kinematics Estimation Accuracy in Learning with Wearable Haptics

Rokhmanova, N., Pearl, O., Kuchenbecker, K. J., Halilaj, E.

Abstract (1 page) presented at the American Society of Biomechanics Annual Meeting (ASB), Knoxville, USA, August 2023 (misc)

hi

Project Page [BibTex]

hi Rokhmanova, N., Pearl, O., Kuchenbecker, K. J., Halilaj, E. The Role of Kinematics Estimation Accuracy in Learning with Wearable Haptics Abstract (1 page) presented at the American Society of Biomechanics Annual Meeting (ASB), Knoxville, USA, August 2023 (misc)

Project Page [BibTex]

Strap Tightness and Tissue Composition Both Affect the Vibration Created by a Wearable Device
Strap Tightness and Tissue Composition Both Affect the Vibration Created by a Wearable Device

Rokhmanova, N., Faulkner, R., Martus, J., Fiene, J., Kuchenbecker, K. J.

Work-in-progress paper (1 page) presented at the IEEE World Haptics Conference (WHC), Delft, The Netherlands, July 2023 (misc)

Abstract
Wearable haptic devices can provide salient real-time feedback (typically vibration) for rehabilitation, sports training, and skill acquisition. Although the body provides many sites for such cues, the influence of the mounting location on vibrotactile mechanics is commonly ignored. This study builds on previous research by quantifying how changes in strap tightness and local tissue composition affect the physical acceleration generated by a typical vibrotactile device.

hi

Project Page [BibTex]

hi Rokhmanova, N., Faulkner, R., Martus, J., Fiene, J., Kuchenbecker, K. J. Strap Tightness and Tissue Composition Both Affect the Vibration Created by a Wearable Device Work-in-progress paper (1 page) presented at the IEEE World Haptics Conference (WHC), Delft, The Netherlands, July 2023 (misc)

Project Page [BibTex]

Toward a Device for Reliable Evaluation of Vibrotactile Perception
Toward a Device for Reliable Evaluation of Vibrotactile Perception

Ballardini, G., Kuchenbecker, K. J.

Work-in-progress paper (1 page) presented at the IEEE World Haptics Conference (WHC), Delft, The Netherlands, July 2023 (misc)

hi

[BibTex]

hi Ballardini, G., Kuchenbecker, K. J. Toward a Device for Reliable Evaluation of Vibrotactile Perception Work-in-progress paper (1 page) presented at the IEEE World Haptics Conference (WHC), Delft, The Netherlands, July 2023 (misc)

[BibTex]

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Multimodal Multi-User Surface Recognition with the Kernel Two-Sample Test: Code

Khojasteh, B., Solowjow, F., Trimpe, S., Kuchenbecker, K. J.

Code published as a companion to the journal article "Multimodal Multi-User Surface Recognition with the Kernel Two-Sample Test" in IEEE Transactions on Automation Science and Engineering, July 2023 (misc)

hi

DOI Project Page [BibTex]

hi Khojasteh, B., Solowjow, F., Trimpe, S., Kuchenbecker, K. J. Multimodal Multi-User Surface Recognition with the Kernel Two-Sample Test: Code Code published as a companion to the journal article "Multimodal Multi-User Surface Recognition with the Kernel Two-Sample Test" in IEEE Transactions on Automation Science and Engineering, July 2023 (misc)

DOI Project Page [BibTex]

Improving Haptic Rendering Quality by Measuring and Compensating for Undesired Forces
Improving Haptic Rendering Quality by Measuring and Compensating for Undesired Forces

Fazlollahi, F., Taghizadeh, Z., Kuchenbecker, K. J.

Work-in-progress paper (1 page) presented at the IEEE World Haptics Conference (WHC), Delft, The Netherlands, July 2023 (misc)

hi

Project Page [BibTex]

hi Fazlollahi, F., Taghizadeh, Z., Kuchenbecker, K. J. Improving Haptic Rendering Quality by Measuring and Compensating for Undesired Forces Work-in-progress paper (1 page) presented at the IEEE World Haptics Conference (WHC), Delft, The Netherlands, July 2023 (misc)

Project Page [BibTex]

Capturing Rich Auditory-Haptic Contact Data for Surface Recognition
Capturing Rich Auditory-Haptic Contact Data for Surface Recognition

Khojasteh, B., Shao, Y., Kuchenbecker, K. J.

Work-in-progress paper (1 page) presented at the IEEE World Haptics Conference (WHC), Delft, The Netherlands, July 2023 (misc)

Abstract
The sophistication of biological sensing and transduction processes during finger-surface and tool-surface interaction is remarkable, enabling humans to perform ubiquitous tasks such as discriminating and manipulating surfaces. Capturing and processing these rich contact-elicited signals during surface exploration with similar success is an important challenge for artificial systems. Prior research introduced sophisticated mobile surface-sensing systems, but it remains less clear what quality, resolution and acuity of sensor data are necessary to perform human tasks with the same efficiency and accuracy. In order to address this gap in our understanding about artificial surface perception, we have designed a novel auditory-haptic test bed. This study aims to inspire new designs for artificial sensing tools in human-machine and robotic applications.

hi

Project Page [BibTex]

hi Khojasteh, B., Shao, Y., Kuchenbecker, K. J. Capturing Rich Auditory-Haptic Contact Data for Surface Recognition Work-in-progress paper (1 page) presented at the IEEE World Haptics Conference (WHC), Delft, The Netherlands, July 2023 (misc)

Project Page [BibTex]

Airo{T}ouch: Naturalistic Vibrotactile Feedback for Telerobotic Construction
AiroTouch: Naturalistic Vibrotactile Feedback for Telerobotic Construction

Gong, Y., Javot, B., Lauer, A. P. R., Sawodny, O., Kuchenbecker, K. J.

Hands-on demonstration presented at the IEEE World Haptics Conference, Delft, The Netherlands, July 2023 (misc)

hi

Project Page [BibTex]

hi Gong, Y., Javot, B., Lauer, A. P. R., Sawodny, O., Kuchenbecker, K. J. AiroTouch: Naturalistic Vibrotactile Feedback for Telerobotic Construction Hands-on demonstration presented at the IEEE World Haptics Conference, Delft, The Netherlands, July 2023 (misc)

Project Page [BibTex]

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CAPT Motor: A Strong Direct-Drive Haptic Interface

Javot, B., Nguyen, V. H., Ballardini, G., Kuchenbecker, K. J.

Hands-on demonstration presented at the IEEE World Haptics Conference, Delft, The Netherlands, July 2023 (misc)

hi

Project Page [BibTex]

hi Javot, B., Nguyen, V. H., Ballardini, G., Kuchenbecker, K. J. CAPT Motor: A Strong Direct-Drive Haptic Interface Hands-on demonstration presented at the IEEE World Haptics Conference, Delft, The Netherlands, July 2023 (misc)

Project Page [BibTex]

Can Recording Expert Demonstrations with Tool Vibrations Facilitate Teaching of Manual Skills?
Can Recording Expert Demonstrations with Tool Vibrations Facilitate Teaching of Manual Skills?

Gourishetti, R., Javot, B., Kuchenbecker, K. J.

Work-in-progress paper (1 page) presented at the IEEE World Haptics Conference (WHC), Delft, The Netherlands, July 2023 (misc)

hi

Project Page [BibTex]

hi Gourishetti, R., Javot, B., Kuchenbecker, K. J. Can Recording Expert Demonstrations with Tool Vibrations Facilitate Teaching of Manual Skills? Work-in-progress paper (1 page) presented at the IEEE World Haptics Conference (WHC), Delft, The Netherlands, July 2023 (misc)

Project Page [BibTex]

Creating a Haptic Empathetic Robot Animal for Children with Autism
Creating a Haptic Empathetic Robot Animal for Children with Autism

Burns, R. B.

Workshop paper (4 pages) presented at the RSS Pioneers Workshop, Daegu, South Korea, July 2023 (misc)

hi

link (url) Project Page [BibTex]

hi Burns, R. B. Creating a Haptic Empathetic Robot Animal for Children with Autism Workshop paper (4 pages) presented at the RSS Pioneers Workshop, Daegu, South Korea, July 2023 (misc)

link (url) Project Page [BibTex]

The Influence of Amplitude and Sharpness on the Perceived Intensity of Isoenergetic Ultrasonic Signals
The Influence of Amplitude and Sharpness on the Perceived Intensity of Isoenergetic Ultrasonic Signals

Gueorguiev, D., Rohou–Claquin, B., Kuchenbecker, K. J.

Work-in-progress paper (1 page) presented at the IEEE World Haptics Conference (WHC), Delft, The Netherlands, July 2023 (misc)

hi

Project Page [BibTex]

hi Gueorguiev, D., Rohou–Claquin, B., Kuchenbecker, K. J. The Influence of Amplitude and Sharpness on the Perceived Intensity of Isoenergetic Ultrasonic Signals Work-in-progress paper (1 page) presented at the IEEE World Haptics Conference (WHC), Delft, The Netherlands, July 2023 (misc)

Project Page [BibTex]