Header logo is


2019


Controlling Heterogeneous Stochastic Growth Processes on Lattices with Limited Resources
Controlling Heterogeneous Stochastic Growth Processes on Lattices with Limited Resources

Haksar, R., Solowjow, F., Trimpe, S., Schwager, M.

In Proceedings of the 58th IEEE International Conference on Decision and Control (CDC) , pages: 1315-1322, 58th IEEE International Conference on Decision and Control (CDC), December 2019 (conference)

ics

PDF [BibTex]

2019


PDF [BibTex]


A Learnable Safety Measure
A Learnable Safety Measure

Heim, S., Rohr, A. V., Trimpe, S., Badri-Spröwitz, A.

Conference on Robot Learning, November 2019 (conference) Accepted

dlg ics

Arxiv [BibTex]

Arxiv [BibTex]


no image
Deep Neural Network Approach in Electrical Impedance Tomography-Based Real-Time Soft Tactile Sensor

Park, H., Lee, H., Park, K., Mo, S., Kim, J.

In Proceedings of the IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), pages: 7447-7452, Macau, China, November 2019 (inproceedings)

Abstract
Recently, a whole-body tactile sensing have emerged in robotics for safe human-robot interaction. A key issue in the whole-body tactile sensing is ensuring large-area manufacturability and high durability. To fulfill these requirements, a reconstruction method called electrical impedance tomography (EIT) was adopted in large-area tactile sensing. This method maps voltage measurements to conductivity distribution using only a few number of measurement electrodes. A common approach for the mapping is using a linearized model derived from the Maxwell's equation. This linearized model shows fast computation time and moderate robustness against measurement noise but reconstruction accuracy is limited. In this paper, we propose a novel nonlinear EIT algorithm through Deep Neural Network (DNN) approach to improve the reconstruction accuracy of EIT-based tactile sensors. The neural network architecture with rectified linear unit (ReLU) function ensured extremely low computational time (0.002 seconds) and nonlinear network structure which provides superior measurement accuracy. The DNN model was trained with dataset synthesized in simulation environment. To achieve the robustness against measurement noise, the training proceeded with additive Gaussian noise that estimated through actual measurement noise. For real sensor application, the trained DNN model was transferred to a conductive fabric-based soft tactile sensor. For validation, the reconstruction error and noise robustness were mainly compared using conventional linearized model and proposed approach in simulation environment. As a demonstration, the tactile sensor equipped with the trained DNN model is presented for a contact force estimation.

hi

DOI [BibTex]

DOI [BibTex]


Predictive Triggering for Distributed Control of Resource Constrained Multi-agent Systems
Predictive Triggering for Distributed Control of Resource Constrained Multi-agent Systems

Mastrangelo, J. M., Baumann, D., Trimpe, S.

In Proceedings of the 8th IFAC Workshop on Distributed Estimation and Control in Networked Systems, pages: 79-84, 8th IFAC Workshop on Distributed Estimation and Control in Networked Systems (NecSys), September 2019 (inproceedings)

ics

arXiv PDF DOI [BibTex]

arXiv PDF DOI [BibTex]


Effect of Remote Masking on Detection of Electrovibration
Effect of Remote Masking on Detection of Electrovibration

Jamalzadeh, M., Güçlü, B., Vardar, Y., Basdogan, C.

In Proceedings of the IEEE World Haptics Conference (WHC), pages: 229-234, Tokyo, Japan, July 2019 (inproceedings)

Abstract
Masking has been used to study human perception of tactile stimuli, including those created on haptic touch screens. Earlier studies have investigated the effect of in-site masking on tactile perception of electrovibration. In this study, we investigated whether it is possible to change detection threshold of electrovibration at fingertip of index finger via remote masking, i.e. by applying a (mechanical) vibrotactile stimulus on the proximal phalanx of the same finger. The masking stimuli were generated by a voice coil (Haptuator). For eight participants, we first measured the detection thresholds for electrovibration at the fingertip and for vibrotactile stimuli at the proximal phalanx. Then, the vibrations on the skin were measured at four different locations on the index finger of subjects to investigate how the mechanical masking stimulus propagated as the masking level was varied. Finally, electrovibration thresholds measured in the presence of vibrotactile masking stimuli. Our results show that vibrotactile masking stimuli generated sub-threshold vibrations around fingertip, and hence did not mechanically interfere with the electrovibration stimulus. However, there was a clear psychophysical masking effect due to central neural processes. Electrovibration absolute threshold increased approximately 0.19 dB for each dB increase in the masking level.

hi

DOI [BibTex]

DOI [BibTex]


Objective and Subjective Assessment of Algorithms for Reducing Three-Axis Vibrations to One-Axis Vibrations
Objective and Subjective Assessment of Algorithms for Reducing Three-Axis Vibrations to One-Axis Vibrations

Park, G., Kuchenbecker, K. J.

In Proceedings of the IEEE World Haptics Conference, pages: 467-472, July 2019 (inproceedings)

Abstract
A typical approach to creating realistic vibrotactile feedback is reducing 3D vibrations recorded by an accelerometer to 1D signals that can be played back on a haptic actuator, but some of the information is often lost in this dimensional reduction process. This paper describes seven representative algorithms and proposes four metrics based on the spectral match, the temporal match, and the average value and the variability of them across 3D rotations. These four performance metrics were applied to four texture recordings, and the method utilizing the discrete fourier transform (DFT) was found to be the best regardless of the sensing axis. We also recruited 16 participants to assess the perceptual similarity achieved by each algorithm in real time. We found the four metrics correlated well with the subjectively rated similarities for the six dimensional reduction algorithms, with the exception of taking the 3D vector magnitude, which was perceived to be good despite its low spectral and temporal match metrics.

hi

DOI [BibTex]

DOI [BibTex]


Event-triggered Pulse Control with Model Learning (if Necessary)
Event-triggered Pulse Control with Model Learning (if Necessary)

Baumann, D., Solowjow, F., Johansson, K. H., Trimpe, S.

In Proceedings of the American Control Conference, pages: 792-797, American Control Conference (ACC), July 2019 (inproceedings)

ics

arXiv PDF Project Page [BibTex]

arXiv PDF Project Page [BibTex]


Fingertip Interaction Metrics Correlate with Visual and Haptic Perception of Real Surfaces
Fingertip Interaction Metrics Correlate with Visual and Haptic Perception of Real Surfaces

Vardar, Y., Wallraven, C., Kuchenbecker, K. J.

In Proceedings of the IEEE World Haptics Conference (WHC), pages: 395-400, Tokyo, Japan, July 2019 (inproceedings)

Abstract
Both vision and touch contribute to the perception of real surfaces. Although there have been many studies on the individual contributions of each sense, it is still unclear how each modality’s information is processed and integrated. To fill this gap, we investigated the similarity of visual and haptic perceptual spaces, as well as how well they each correlate with fingertip interaction metrics. Twenty participants interacted with ten different surfaces from the Penn Haptic Texture Toolkit by either looking at or touching them and judged their similarity in pairs. By analyzing the resulting similarity ratings using multi-dimensional scaling (MDS), we found that surfaces are similarly organized within the three-dimensional perceptual spaces of both modalities. Also, between-participant correlations were significantly higher in the haptic condition. In a separate experiment, we obtained the contact forces and accelerations acting on one finger interacting with each surface in a controlled way. We analyzed the collected fingertip interaction data in both the time and frequency domains. Our results suggest that the three perceptual dimensions for each modality can be represented by roughness/smoothness, hardness/softness, and friction, and that these dimensions can be estimated by surface vibration power, tap spectral centroid, and kinetic friction coefficient, respectively.

hi

DOI Project Page [BibTex]

DOI Project Page [BibTex]


Data-driven inference of passivity properties via Gaussian process optimization
Data-driven inference of passivity properties via Gaussian process optimization

Romer, A., Trimpe, S., Allgöwer, F.

In Proceedings of the European Control Conference, European Control Conference (ECC), June 2019 (inproceedings)

ics

PDF [BibTex]

PDF [BibTex]


Trajectory-Based Off-Policy Deep Reinforcement Learning
Trajectory-Based Off-Policy Deep Reinforcement Learning

Doerr, A., Volpp, M., Toussaint, M., Trimpe, S., Daniel, C.

In Proceedings of the International Conference on Machine Learning (ICML), International Conference on Machine Learning (ICML), June 2019 (inproceedings)

Abstract
Policy gradient methods are powerful reinforcement learning algorithms and have been demonstrated to solve many complex tasks. However, these methods are also data-inefficient, afflicted with high variance gradient estimates, and frequently get stuck in local optima. This work addresses these weaknesses by combining recent improvements in the reuse of off-policy data and exploration in parameter space with deterministic behavioral policies. The resulting objective is amenable to standard neural network optimization strategies like stochastic gradient descent or stochastic gradient Hamiltonian Monte Carlo. Incorporation of previous rollouts via importance sampling greatly improves data-efficiency, whilst stochastic optimization schemes facilitate the escape from local optima. We evaluate the proposed approach on a series of continuous control benchmark tasks. The results show that the proposed algorithm is able to successfully and reliably learn solutions using fewer system interactions than standard policy gradient methods.

ics

arXiv PDF [BibTex]

arXiv PDF [BibTex]


Haptipedia: Accelerating Haptic Device Discovery to Support Interaction & Engineering Design
Haptipedia: Accelerating Haptic Device Discovery to Support Interaction & Engineering Design

Seifi, H., Fazlollahi, F., Oppermann, M., Sastrillo, J. A., Ip, J., Agrawal, A., Park, G., Kuchenbecker, K. J., MacLean, K. E.

In Proceedings of the ACM SIGCHI Conference on Human Factors in Computing Systems (CHI), Glasgow, Scotland, May 2019 (inproceedings)

Abstract
Creating haptic experiences often entails inventing, modifying, or selecting specialized hardware. However, experience designers are rarely engineers, and 30 years of haptic inventions are buried in a fragmented literature that describes devices mechanically rather than by potential purpose. We conceived of Haptipedia to unlock this trove of examples: Haptipedia presents a device corpus for exploration through metadata that matter to both device and experience designers. It is a taxonomy of device attributes that go beyond physical description to capture potential utility, applied to a growing database of 105 grounded force-feedback devices, and accessed through a public visualization that links utility to morphology. Haptipedia's design was driven by both systematic review of the haptic device literature and rich input from diverse haptic designers. We describe Haptipedia's reception (including hopes it will redefine device reporting standards) and our plans for its sustainability through community participation.

hi

Project Page [BibTex]

Project Page [BibTex]


no image
Internal Array Electrodes Improve the Spatial Resolution of Soft Tactile Sensors Based on Electrical Resistance Tomography

Lee, H., Park, K., Kim, J., Kuchenbecker, K. J.

In Proceedings of the IEEE International Conference on Robotics and Automation (ICRA), pages: 5411-5417, Montreal, Canada, May 2019, Hyosang Lee and Kyungseo Park contributed equally to this publication (inproceedings)

hi

link (url) DOI Project Page [BibTex]

link (url) DOI Project Page [BibTex]


no image
A Clustering Approach to Categorizing 7 Degree-of-Freedom Arm Motions during Activities of Daily Living

Gloumakov, Y., Spiers, A. J., Dollar, A. M.

In Proceedings of the International Conference on Robotics and Automation (ICRA), pages: 7214-7220, Montreal, Canada, May 2019 (inproceedings)

Abstract
In this paper we present a novel method of categorizing naturalistic human arm motions during activities of daily living using clustering techniques. While many current approaches attempt to define all arm motions using heuristic interpretation, or a combination of several abstract motion primitives, our unsupervised approach generates a hierarchical description of natural human motion with well recognized groups. Reliable recommendation of a subset of motions for task achievement is beneficial to various fields, such as robotic and semi-autonomous prosthetic device applications. The proposed method makes use of well-known techniques such as dynamic time warping (DTW) to obtain a divergence measure between motion segments, DTW barycenter averaging (DBA) to get a motion average, and Ward's distance criterion to build the hierarchical tree. The clusters that emerge summarize the variety of recorded motions into the following general tasks: reach-to-front, transfer-box, drinking from vessel, on-table motion, turning a key or door knob, and reach-to-back pocket. The clustering methodology is justified by comparing against an alternative measure of divergence using Bezier coefficients and K-medoids clustering.

hi

DOI [BibTex]

DOI [BibTex]


Improving Haptic Adjective Recognition with Unsupervised Feature Learning
Improving Haptic Adjective Recognition with Unsupervised Feature Learning

Richardson, B. A., Kuchenbecker, K. J.

In Proceedings of the IEEE International Conference on Robotics and Automation (ICRA), pages: 3804-3810, Montreal, Canada, May 2019 (inproceedings)

Abstract
Humans can form an impression of how a new object feels simply by touching its surfaces with the densely innervated skin of the fingertips. Many haptics researchers have recently been working to endow robots with similar levels of haptic intelligence, but these efforts almost always employ hand-crafted features, which are brittle, and concrete tasks, such as object recognition. We applied unsupervised feature learning methods, specifically K-SVD and Spatio-Temporal Hierarchical Matching Pursuit (ST-HMP), to rich multi-modal haptic data from a diverse dataset. We then tested the learned features on 19 more abstract binary classification tasks that center on haptic adjectives such as smooth and squishy. The learned features proved superior to traditional hand-crafted features by a large margin, almost doubling the average F1 score across all adjectives. Additionally, particular exploratory procedures (EPs) and sensor channels were found to support perception of certain haptic adjectives, underlining the need for diverse interactions and multi-modal haptic data.

hi

link (url) DOI Project Page [BibTex]

link (url) DOI Project Page [BibTex]


Feedback Control Goes Wireless: Guaranteed Stability over Low-power Multi-hop Networks
Feedback Control Goes Wireless: Guaranteed Stability over Low-power Multi-hop Networks

(Best Paper Award)

Mager, F., Baumann, D., Jacob, R., Thiele, L., Trimpe, S., Zimmerling, M.

In Proceedings of the 10th ACM/IEEE International Conference on Cyber-Physical Systems, pages: 97-108, 10th ACM/IEEE International Conference on Cyber-Physical Systems, April 2019 (inproceedings)

Abstract
Closing feedback loops fast and over long distances is key to emerging applications; for example, robot motion control and swarm coordination require update intervals below 100 ms. Low-power wireless is preferred for its flexibility, low cost, and small form factor, especially if the devices support multi-hop communication. Thus far, however, closed-loop control over multi-hop low-power wireless has only been demonstrated for update intervals on the order of multiple seconds. This paper presents a wireless embedded system that tames imperfections impairing control performance such as jitter or packet loss, and a control design that exploits the essential properties of this system to provably guarantee closed-loop stability for linear dynamic systems. Using experiments on a testbed with multiple cart-pole systems, we are the first to demonstrate the feasibility and to assess the performance of closed-loop control and coordination over multi-hop low-power wireless for update intervals from 20 ms to 50 ms.

ics

arXiv PDF DOI Project Page [BibTex]

arXiv PDF DOI Project Page [BibTex]


A Novel Texture Rendering Approach for Electrostatic Displays
A Novel Texture Rendering Approach for Electrostatic Displays

Fiedler, T., Vardar, Y.

In Proceedings of International Workshop on Haptic and Audio Interaction Design (HAID), Lille, France, March 2019 (inproceedings)

Abstract
Generating realistic texture feelings on tactile displays using data-driven methods has attracted a lot of interest in the last decade. However, the need for large data storages and transmission rates complicates the use of these methods for the future commercial displays. In this paper, we propose a new texture rendering approach which can compress the texture data signicantly for electrostatic displays. Using three sample surfaces, we first explain how to record, analyze and compress the texture data, and render them on a touchscreen. Then, through psychophysical experiments conducted with nineteen participants, we show that the textures can be reproduced by a signicantly less number of frequency components than the ones in the original signal without inducing perceptual degradation. Moreover, our results indicate that the possible degree of compression is affected by the surface properties.

hi

Fiedler19-HAID-Electrostatic [BibTex]

Fiedler19-HAID-Electrostatic [BibTex]

2017


On the Design of {LQR} Kernels for Efficient Controller Learning
On the Design of LQR Kernels for Efficient Controller Learning

Marco, A., Hennig, P., Schaal, S., Trimpe, S.

Proceedings of the 56th IEEE Annual Conference on Decision and Control (CDC), pages: 5193-5200, IEEE, IEEE Conference on Decision and Control, December 2017 (conference)

Abstract
Finding optimal feedback controllers for nonlinear dynamic systems from data is hard. Recently, Bayesian optimization (BO) has been proposed as a powerful framework for direct controller tuning from experimental trials. For selecting the next query point and finding the global optimum, BO relies on a probabilistic description of the latent objective function, typically a Gaussian process (GP). As is shown herein, GPs with a common kernel choice can, however, lead to poor learning outcomes on standard quadratic control problems. For a first-order system, we construct two kernels that specifically leverage the structure of the well-known Linear Quadratic Regulator (LQR), yet retain the flexibility of Bayesian nonparametric learning. Simulations of uncertain linear and nonlinear systems demonstrate that the LQR kernels yield superior learning performance.

am ics pn

arXiv PDF On the Design of LQR Kernels for Efficient Controller Learning - CDC presentation DOI Project Page [BibTex]

2017


arXiv PDF On the Design of LQR Kernels for Efficient Controller Learning - CDC presentation DOI Project Page [BibTex]


no image
Synchronicity Trumps Mischief in Rhythmic Human-Robot Social-Physical Interaction

Fitter, N. T., Kuchenbecker, K. J.

In Proceedings of the International Symposium on Robotics Research (ISRR), Puerto Varas, Chile, December 2017 (inproceedings) In press

Abstract
Hand-clapping games and other forms of rhythmic social-physical interaction might help foster human-robot teamwork, but the design of such interactions has scarcely been explored. We leveraged our prior work to enable the Rethink Robotics Baxter Research Robot to competently play one-handed tempo-matching hand-clapping games with a human user. To understand how such a robot’s capabilities and behaviors affect user perception, we created four versions of this interaction: the hand clapping could be initiated by either the robot or the human, and the non-initiating partner could be either cooperative, yielding synchronous motion, or mischievously uncooperative. Twenty adults tested two clapping tempos in each of these four interaction modes in a random order, rating every trial on standardized scales. The study results showed that having the robot initiate the interaction gave it a more dominant perceived personality. Despite previous results on the intrigue of misbehaving robots, we found that moving synchronously with the robot almost always made the interaction more enjoyable, less mentally taxing, less physically demanding, and lower effort for users than asynchronous interactions caused by robot or human mischief. Taken together, our results indicate that cooperative rhythmic social-physical interaction has the potential to strengthen human-robot partnerships.

hi

[BibTex]

[BibTex]


Optimizing Long-term Predictions for Model-based Policy Search
Optimizing Long-term Predictions for Model-based Policy Search

Doerr, A., Daniel, C., Nguyen-Tuong, D., Marco, A., Schaal, S., Toussaint, M., Trimpe, S.

Proceedings of 1st Annual Conference on Robot Learning (CoRL), 78, pages: 227-238, (Editors: Sergey Levine and Vincent Vanhoucke and Ken Goldberg), 1st Annual Conference on Robot Learning, November 2017 (conference)

Abstract
We propose a novel long-term optimization criterion to improve the robustness of model-based reinforcement learning in real-world scenarios. Learning a dynamics model to derive a solution promises much greater data-efficiency and reusability compared to model-free alternatives. In practice, however, modelbased RL suffers from various imperfections such as noisy input and output data, delays and unmeasured (latent) states. To achieve higher resilience against such effects, we propose to optimize a generative long-term prediction model directly with respect to the likelihood of observed trajectories as opposed to the common approach of optimizing a dynamics model for one-step-ahead predictions. We evaluate the proposed method on several artificial and real-world benchmark problems and compare it to PILCO, a model-based RL framework, in experiments on a manipulation robot. The results show that the proposed method is competitive compared to state-of-the-art model learning methods. In contrast to these more involved models, our model can directly be employed for policy search and outperforms a baseline method in the robot experiment.

am ics

PDF Project Page [BibTex]

PDF Project Page [BibTex]


A Robotic Framework to Overcome Sensory Overload in Children on the Autism Spectrum: A Pilot Study
A Robotic Framework to Overcome Sensory Overload in Children on the Autism Spectrum: A Pilot Study

Javed, H., Burns, R., Jeon, M., Howard, A., Park, C. H.

In International Conference on Intelligent Robots and Systems (IROS) 2017, International Conference on Intelligent Robots and Systems, September 2017 (inproceedings)

Abstract
This paper discusses a novel framework designed to provide sensory stimulation to children with Autism Spectrum Disorder (ASD). The set up consists of multi-sensory stations to stimulate visual/auditory/olfactory/gustatory/tactile/vestibular senses, together with a robotic agent that navigates through each station responding to the different stimuli. We hypothesize that the robot’s responses will help children learn acceptable ways to respond to stimuli that might otherwise trigger sensory overload. Preliminary results from a pilot study conducted to examine the effectiveness of such a setup were encouraging and are described briefly in this text.

hi

[BibTex]

[BibTex]


An Interactive Robotic System for Promoting Social Engagement
An Interactive Robotic System for Promoting Social Engagement

Burns, R., Javed, H., Jeon, M., Howard, A., Park, C. H.

In International Conference on Intelligent Robots and Systems (IROS) 2017, International Conference on Intelligent Robots and Systems, September 2017 (inproceedings)

Abstract
This abstract (and poster) is a condensed version of Burns' Master's thesis and related journal article. It discusses the use of imitation via robotic motion learning to improve human-robot interaction. It focuses on the preliminary results from a pilot study of 12 subjects. We hypothesized that the robot's use of imitation will increase the user's openness towards engaging with the robot. Post-imitation, experimental subjects displayed a more positive emotional state, had higher instances of mood contagion towards the robot, and interpreted the robot to have a higher level of autonomy than their control group counterparts. These results point to an increased user interest in engagement fueled by personalized imitation during interaction.

hi

[BibTex]

[BibTex]


no image
Stiffness Perception during Pinching and Dissection with Teleoperated Haptic Forceps

Ng, C., Zareinia, K., Sun, Q., Kuchenbecker, K. J.

In Proceedings of the International Symposium on Robot and Human Interactive Communication (RO-MAN), pages: 456-463, Lisbon, Portugal, August 2017 (inproceedings)

hi

link (url) DOI [BibTex]

link (url) DOI [BibTex]


no image
Towards quantifying dynamic human-human physical interactions for robot assisted stroke therapy

Mohan, M., Mendonca, R., Johnson, M. J.

In Proceedings of the IEEE International Conference on Rehabilitation Robotics (ICORR), London, UK, July 2017 (inproceedings)

Abstract
Human-Robot Interaction is a prominent field of robotics today. Knowledge of human-human physical interaction can prove vital in creating dynamic physical interactions between human and robots. Most of the current work in studying this interaction has been from a haptic perspective. Through this paper, we present metrics that can be used to identify if a physical interaction occurred between two people using kinematics. We present a simple Activity of Daily Living (ADL) task which involves a simple interaction. We show that we can use these metrics to successfully identify interactions.

hi

DOI [BibTex]

DOI [BibTex]


no image
Design of a Parallel Continuum Manipulator for 6-DOF Fingertip Haptic Display

Young, E. M., Kuchenbecker, K. J.

In Proceedings of the IEEE World Haptics Conference (WHC), pages: 599-604, Munich, Germany, June 2017, Finalist for best poster paper (inproceedings)

Abstract
Despite rapid advancements in the field of fingertip haptics, rendering tactile cues with six degrees of freedom (6 DOF) remains an elusive challenge. In this paper, we investigate the potential of displaying fingertip haptic sensations with a 6-DOF parallel continuum manipulator (PCM) that mounts to the user's index finger and moves a contact platform around the fingertip. Compared to traditional mechanisms composed of rigid links and discrete joints, PCMs have the potential to be strong, dexterous, and compact, but they are also more complicated to design. We define the design space of 6-DOF parallel continuum manipulators and outline a process for refining such a device for fingertip haptic applications. Following extensive simulation, we obtain 12 designs that meet our specifications, construct a manually actuated prototype of one such design, and evaluate the simulation's ability to accurately predict the prototype's motion. Finally, we demonstrate the range of deliverable fingertip tactile cues, including a normal force into the finger and shear forces tangent to the finger at three extreme points on the boundary of the fingertip.

hi

DOI Project Page [BibTex]

DOI Project Page [BibTex]


no image
High Magnitude Unidirectional Haptic Force Display Using a Motor/Brake Pair and a Cable

Hu, S., Kuchenbecker, K. J.

In Proceedings of the IEEE World Haptics Conference (WHC), pages: 394-399, Munich, Germany, June 2017 (inproceedings)

Abstract
Clever electromechanical design is required to make the force feedback delivered by a kinesthetic haptic interface both strong and safe. This paper explores a onedimensional haptic force display that combines a DC motor and a magnetic particle brake on the same shaft. Rather than a rigid linkage, a spooled cable connects the user to the actuators to enable a large workspace, reduce the moving mass, and eliminate the sticky residual force from the brake. This design combines the high torque/power ratio of the brake and the active output capabilities of the motor to provide a wider range of forces than can be achieved with either actuator alone. A prototype of this device was built, its performance was characterized, and it was used to simulate constant force sources and virtual springs and dampers. Compared to the conventional design of using only a motor, the hybrid device can output higher unidirectional forces at the expense of free space feeling less free.

hi

DOI Project Page [BibTex]

DOI Project Page [BibTex]


no image
A Stimulus-Response Model Of Therapist-Patient Interactions In Task-Oriented Stroke Therapy Can Guide Robot-Patient Interactions

Johnson, M., Mohan, M., Mendonca, R.

In Proceedings of the Annual Rehabilitation Engineering and Assistive Technology Society of North America (RESNA) Conference, New Orleans, USA, June 2017 (inproceedings)

Abstract
Current robot-patient interactions do not accurately model therapist-patient interactions in task-oriented stroke therapy. We analyzed patient-therapist interactions in task-oriented stroke therapy captured in 8 videos. We developed a model of the interaction between a patient and a therapist that can be overlaid on a stimulus-response paradigm where the therapist and the patient take on a set of acting states or roles and are motivated to move from one role to another when certain physical or verbal stimuli or cues are sensed and received. We examined how the model varies across 8 activities of daily living tasks and map this to a possible model for robot-patient interaction.

hi

link (url) [BibTex]

link (url) [BibTex]


no image
A Wrist-Squeezing Force-Feedback System for Robotic Surgery Training

Brown, J. D., Fernandez, J. N., Cohen, S. P., Kuchenbecker, K. J.

In Proceedings of the IEEE World Haptics Conference (WHC), pages: 107-112, Munich, Germany, June 2017 (inproceedings)

Abstract
Over time, surgical trainees learn to compensate for the lack of haptic feedback in commercial robotic minimally invasive surgical systems. Incorporating touch cues into robotic surgery training could potentially shorten this learning process if the benefits of haptic feedback were sustained after it is removed. In this paper, we develop a wrist-squeezing haptic feedback system and evaluate whether it holds the potential to train novice da Vinci users to reduce the force they exert on a bimanual inanimate training task. Subjects were randomly divided into two groups according to a multiple baseline experimental design. Each of the ten participants moved a ring along a curved wire nine times while the haptic feedback was conditionally withheld, provided, and withheld again. The realtime tactile feedback of applied force magnitude significantly reduced the integral of the force produced by the da Vinci tools on the task materials, and this result remained even when the haptic feedback was removed. Overall, our findings suggest that wrist-squeezing force feedback can play an essential role in helping novice trainees learn to minimize the force they exert with a surgical robot.

hi

DOI [BibTex]

DOI [BibTex]


no image
Handling Scan-Time Parameters in Haptic Surface Classification

Burka, A., Kuchenbecker, K. J.

In Proceedings of the IEEE World Haptics Conference (WHC), pages: 424-429, Munich, Germany, June 2017 (inproceedings)

hi

DOI Project Page [BibTex]

DOI Project Page [BibTex]


Model-Based Policy Search for Automatic Tuning of Multivariate PID Controllers
Model-Based Policy Search for Automatic Tuning of Multivariate PID Controllers

Doerr, A., Nguyen-Tuong, D., Marco, A., Schaal, S., Trimpe, S.

In Proceedings of the IEEE International Conference on Robotics and Automation (ICRA), pages: 5295-5301, IEEE, Piscataway, NJ, USA, IEEE International Conference on Robotics and Automation (ICRA), May 2017 (inproceedings)

am ics

PDF arXiv DOI Project Page [BibTex]

PDF arXiv DOI Project Page [BibTex]


Virtual vs. {R}eal: Trading Off Simulations and Physical Experiments in Reinforcement Learning with {B}ayesian Optimization
Virtual vs. Real: Trading Off Simulations and Physical Experiments in Reinforcement Learning with Bayesian Optimization

Marco, A., Berkenkamp, F., Hennig, P., Schoellig, A. P., Krause, A., Schaal, S., Trimpe, S.

In Proceedings of the IEEE International Conference on Robotics and Automation (ICRA), pages: 1557-1563, IEEE, Piscataway, NJ, USA, IEEE International Conference on Robotics and Automation (ICRA), May 2017 (inproceedings)

am ics pn

PDF arXiv ICRA 2017 Spotlight presentation Virtual vs. Real - Video explanation DOI Project Page [BibTex]

PDF arXiv ICRA 2017 Spotlight presentation Virtual vs. Real - Video explanation DOI Project Page [BibTex]


no image
Proton 2: Increasing the Sensitivity and Portability of a Visuo-haptic Surface Interaction Recorder

Burka, A., Rajvanshi, A., Allen, S., Kuchenbecker, K. J.

In Proceedings of the IEEE International Conference on Robotics and Automation (ICRA), pages: 439-445, Singapore, May 2017 (inproceedings)

Abstract
The Portable Robotic Optical/Tactile ObservatioN PACKage (PROTONPACK, or Proton for short) is a new handheld visuo-haptic sensing system that records surface interactions. We previously demonstrated system calibration and a classification task using external motion tracking. This paper details improvements in surface classification performance and removal of the dependence on external motion tracking, necessary before embarking on our goal of gathering a vast surface interaction dataset. Two experiments were performed to refine data collection parameters. After adjusting the placement and filtering of the Proton's high-bandwidth accelerometers, we recorded interactions between two differently-sized steel tooling ball end-effectors (diameter 6.35 and 9.525 mm) and five surfaces. Using features based on normal force, tangential force, end-effector speed, and contact vibration, we trained multi-class SVMs to classify the surfaces using 50 ms chunks of data from each end-effector. Classification accuracies of 84.5% and 91.5% respectively were achieved on unseen test data, an improvement over prior results. In parallel, we pursued on-board motion tracking, using the Proton's camera and fiducial markers. Motion tracks from the external and onboard trackers agree within 2 mm and 0.01 rad RMS, and the accuracy decreases only slightly to 87.7% when using onboard tracking for the 9.525 mm end-effector. These experiments indicate that the Proton 2 is ready for portable data collection.

hi

DOI Project Page [BibTex]

DOI Project Page [BibTex]


Robot Therapist for Assisting in At-Home Rehabilitation of Shoulder Surgery Patients
Robot Therapist for Assisting in At-Home Rehabilitation of Shoulder Surgery Patients

(Recipient of Innovation & Entrepreneurship Prize)

Burns, R., Alborz, M., Chalup, Z., Downen, S., Genuino, K., Nayback, C., Nesbitt, N., Park, C. H.

In 2017 GW Research Days, Department of Biomedical Engineering Posters and Presentations, April 2017 (inproceedings)

Abstract
The number of middle-aged to elderly patients receiving shoulder surgery is increasing. However, statistically, very few of these patients perform the necessary at-home physical therapy regimen they are prescribed post-surgery. This results in longer recovery times and/or incomplete healing. We propose the use of a robotic therapist, with customized training and encouragement regimens, to increase physical therapy adherence and improve the patient’s recovery experience.

hi

link (url) [BibTex]

link (url) [BibTex]


Motion Learning for Emotional Interaction and Imitation of Children with Autism Spectrum Disorder
Motion Learning for Emotional Interaction and Imitation of Children with Autism Spectrum Disorder

(First place tie in category, "Biomedical Engineering, Graduate Research")

Burns, R., Cowin, S.

In 2017 GW Research Days, Department of Biomedical Engineering Posters and Presentations, April 2017 (inproceedings)

Abstract
We aim to use motion learning to teach a robot to imitate people's unique gestures. Our robot, ROBOTIS-OP2, can ultimately use imitation to practice social skills with children with autism. In this abstract, two methods of motion learning were compared: Dynamic motion primitives with least squares (DMP with WLS), and Dynamic motion primitives with a Gaussian Mixture Regression (DMP with GMR). Movements with sharp turns were most accurately reproduced using DMP with GMR. Additionally, more states are required to accurately recreate more complex gestures.

hi

link (url) [BibTex]

link (url) [BibTex]


Roughness perception of virtual textures displayed by electrovibration on touch screens
Roughness perception of virtual textures displayed by electrovibration on touch screens

Vardar, Y., Isleyen, A., Saleem, M. K., Basdogan, C.

In 2017 IEEE World Haptics Conference (WHC), pages: 263-268, 2017 (inproceedings)

Abstract
In this study, we have investigated the human roughness perception of periodical textures on an electrostatic display by conducting psychophysical experiments with 10 subjects. To generate virtual textures, we used low frequency unipolar pulse waves in different waveform (sinusoidal, square, saw-tooth, triangle), and spacing. We modulated these waves with a 3kHz high frequency sinusoidal carrier signal to minimize perceptional differences due to the electrical filtering of human finger and eliminate low-frequency distortions. The subjects were asked to rate 40 different macro textures on a Likert scale of 1-7. We also collected the normal and tangential forces acting on the fingers of subjects during the experiment. The results of our user study showed that subjects perceived the square wave as the roughest while they perceived the other waveforms equally rough. The perceived roughness followed an inverted U-shaped curve as a function of groove width, but the peak point shifted to the left compared to the results of the earlier studies. Moreover, we found that the roughness perception of subjects is best correlated with the rate of change of the contact forces rather than themselves.

hi

vardar_whc2017 DOI [BibTex]

vardar_whc2017 DOI [BibTex]


no image
Feeling multiple edges: The tactile perception of short ultrasonic square reductions of the finger-surface friction

Gueorguiev, D., Vezzoli, E., Sednaoui, T., Grisoni, L., Lemaire-Semail, B.

In 2017 IEEE World Haptics Conference (WHC), pages: 125-129, 2017 (inproceedings)

hi

DOI [BibTex]

DOI [BibTex]

2014


no image
Automatic Skill Evaluation for a Needle Passing Task in Robotic Surgery

Leung, S., Kuchenbecker, K. J.

In Proc. IROS Workshop on the Role of Human Sensorimotor Control in Robotic Surgery, Chicago, Illinois, sep 2014, Poster presentation given by Kuchenbecker. Best Poster Award (inproceedings)

hi

[BibTex]

2014


[BibTex]


no image
A Data-driven Approach to Remote Tactile Interaction: From a BioTac Sensor to Any Fingertip Cutaneous Device

Pacchierotti, C., Prattichizzo, D., Kuchenbecker, K. J.

In Haptics: Neuroscience, Devices, Modeling, and Applications, Proc. EuroHaptics, Part I, 8618, pages: 418-424, Lecture Notes in Computer Science, Springer-Verlag, Berlin Heidelberg, June 2014, Poster presentation given by Pacchierotti in Versailles, France (inproceedings)

hi

[BibTex]

[BibTex]


no image
Evaluating the BioTac’s Ability to Detect and Characterize Lumps in Simulated Tissue

Hui, J. C. T., Kuchenbecker, K. J.

In Haptics: Neuroscience, Devices, Modeling, and Applications, Proc. EuroHaptics, Part II, 8619, pages: 295-302, Lecture Notes in Computer Science, Springer-Verlag, Berlin Heidelberg, June 2014, Poster presentation given by Hui in Versailles, France (inproceedings)

hi

[BibTex]

[BibTex]


no image
Analyzing Human High-Fives to Create an Effective High-Fiving Robot

Fitter, N. T., Kuchenbecker, K. J.

In Proc. ACM/IEEE International Conference on Human-Robot Interaction (HRI), pages: 156-157, Bielefeld, Germany, March 2014, Poster presentation given by Fitter (inproceedings)

hi

[BibTex]

[BibTex]


no image
Dynamic Modeling and Control of Voice-Coil Actuators for High-Fidelity Display of Haptic Vibrations

McMahan, W., Kuchenbecker, K. J.

In Proc. IEEE Haptics Symposium, pages: 115-122, Houston, Texas, USA, February 2014, Oral presentation given by Kuchenbecker (inproceedings)

hi

[BibTex]

[BibTex]


no image
A Wearable Device for Controlling a Robot Gripper With Fingertip Contact, Pressure, Vibrotactile, and Grip Force Feedback

Pierce, R. M., Fedalei, E. A., Kuchenbecker, K. J.

In Proc. IEEE Haptics Symposium, pages: 19-25, Houston, Texas, USA, February 2014, Oral presentation given by Pierce (inproceedings)

hi

[BibTex]

[BibTex]


no image
Methods for Robotic Tool-Mediated Haptic Surface Recognition

Romano, J. M., Kuchenbecker, K. J.

In Proc. IEEE Haptics Symposium, pages: 49-56, Houston, Texas, USA, February 2014, Oral presentation given by Kuchenbecker. Finalist for Best Paper Award (inproceedings)

hi

[BibTex]

[BibTex]


no image
One Hundred Data-Driven Haptic Texture Models and Open-Source Methods for Rendering on 3D Objects

Culbertson, H., Delgado, J. J. L., Kuchenbecker, K. J.

In Proc. IEEE Haptics Symposium, pages: 319-325, Houston, Texas, USA, February 2014, Poster presentation given by Culbertson. Finalist for Best Poster Award (inproceedings)

hi

[BibTex]

[BibTex]


no image
A Self-Tuning LQR Approach Demonstrated on an Inverted Pendulum

Trimpe, S., Millane, A., Doessegger, S., D’Andrea, R.

In Proceedings of the 19th IFAC World Congress, Cape Town, South Africa, 2014 (inproceedings)

am ics

PDF Supplementary material DOI [BibTex]

PDF Supplementary material DOI [BibTex]


no image
Cutaneous Feedback of Planar Fingertip Deformation and Vibration on a da Vinci Surgical Robot

Pacchierotti, C., Shirsat, P., Koehn, J. K., Prattichizzo, D., Kuchenbecker, K. J.

In Proc. IROS Workshop on the Role of Human Sensorimotor Control in Robotic Surgery, Chicago, Illinois, 2014, Poster presentation given by Koehn (inproceedings)

hi

[BibTex]

[BibTex]


no image
Stability Analysis of Distributed Event-Based State Estimation

Trimpe, S.

In Proceedings of the 53rd IEEE Conference on Decision and Control, Los Angeles, CA, 2014 (inproceedings)

Abstract
An approach for distributed and event-based state estimation that was proposed in previous work [1] is analyzed and extended to practical networked systems in this paper. Multiple sensor-actuator-agents observe a dynamic process, sporadically exchange their measurements over a broadcast network according to an event-based protocol, and estimate the process state from the received data. The event-based approach was shown in [1] to mimic a centralized Luenberger observer up to guaranteed bounds, under the assumption of identical estimates on all agents. This assumption, however, is unrealistic (it is violated by a single packet drop or slight numerical inaccuracy) and removed herein. By means of a simulation example, it is shown that non-identical estimates can actually destabilize the overall system. To achieve stability, the event-based communication scheme is supplemented by periodic (but infrequent) exchange of the agentsâ?? estimates and reset to their joint average. When the local estimates are used for feedback control, the stability guarantee for the estimation problem extends to the event-based control system.

am ics

PDF Supplementary material DOI Project Page [BibTex]

PDF Supplementary material DOI Project Page [BibTex]


no image
Increasing the sensor performance using Au modified high temperature superconducting YBa2Cu3O7-delta thin films

Katzer, C., Stahl, C., Michalowski, P., Treiber, S., Westernhausen, M., Schmidl, F., Seidel, P., Schütz, G., Albrecht, J.

In 507, IOP Pub., Genova, Italy, 2014 (inproceedings)

mms

DOI [BibTex]

DOI [BibTex]

2007


no image
The power of external mentors for women pursuing academic careers in engineering and science: Stories of MentorNet ACE and its Proteges and Mentors

Muller, C. B., Smith, E. H. B., Chou-Green, J., Daniels-Race, T., Drummond, A., Kuchenbecker, K. J.

In Proc. Women in Engineering Programs and Advocates Network (WEPAN) National Conference, Lake Buena Vista, Florida, USA, June 2007, Oral presentation given by Muller (inproceedings)

hi

[BibTex]

2007


[BibTex]


no image
Effects of Visual and Proprioceptive Position Feedback on Human Control of Targeted Movement

Kuchenbecker, K. J., Gurari, N., Okamura, A. M.

In Proc. IEEE International Conference on Rehabilitation Robotics, pages: 513-524, Noordwijk, Netherlands, June 2007, Oral and poster presentations given by Kuchenbecker (inproceedings)

hi

[BibTex]

[BibTex]


no image
Quantifying the value of visual and haptic position feedback in force-based motion control

Kuchenbecker, K. J., Gurari, N., Okamura, A. M.

In Proc. IEEE World Haptics Conference, pages: 561-562, Tsukuba, Japan, March 2007, Poster presentation given by Kuchenbecker (inproceedings)

hi

[BibTex]

[BibTex]