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Haptic Intelligence Miscellaneous Explorations of Shape-Changing Haptic Interfaces for Blind and Sighted Pedestrian Navigation Spiers, A., Kuchenbecker, K. J. Workshop paper (6 pages) presented at the CHI Workshop on Hacking Blind Navigation, Glasgow, UK, May 2019 (Published)
Since the 1960s, technologists have worked to develop systems that facilitate independent navigation by vision-impaired (VI) pedestrians. These devices vary in terms of conveyed information and feedback modality. Unfortunately, many such prototypes never progress beyond laboratory testing. Conversely, smartphone-based navigation systems for sighted pedestrians have grown in robustness and capabilities, to the point of now being ubiquitous. How can we leverage the success of sighted navigation technology, which is driven by a larger global market, as a way to progress VI navigation systems? We believe one possibility is to make common devices that benefit both VI and sighted individuals, by providing information in a way that does not distract either user from their tasks or environment. To this end we have developed physical interfaces that eschew visual, audio or vibratory feedback, instead relying on the natural human ability to perceive the shape of a handheld object.
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Empirical Inference Conference Paper Foundations and New Horizons for Causal Inference Meinshausen, N., Peters, J., Richardson, T. S., Schölkopf, B. In Oberwolfach Reports, 16(2):1499-1571, May 2019 (Published) DOI URL BibTeX
Haptic Intelligence Conference Paper 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), 1-12, Glasgow, UK, May 2019 (Published)
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.
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Haptic Intelligence Conference Paper 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), 3804-3810, Montreal, Canada, May 2019 (Published)
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.
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Haptic Intelligence Conference Paper 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), 5411-5417, Montreal, Canada, May 2019, Hyosang Lee and Kyungseo Park contributed equally to this publication (Published) DOI BibTeX
Autonomous Motion Conference Paper Learning Latent Space Dynamics for Tactile Servoing Sutanto, G., Ratliff, N., Sundaralingam, B., Chebotar, Y., Su, Z., Handa, A., Fox, D. In Proceedings of the IEEE International Conference on Robotics and Automation (ICRA) 2019, IEEE, International Conference on Robotics and Automation, May 2019 (Accepted) pdf video BibTeX
Autonomous Motion Movement Generation and Control Conference Paper Leveraging Contact Forces for Learning to Grasp Merzic, H., Bogdanovic, M., Kappler, D., Righetti, L., Bohg, J. In Proceedings of the IEEE International Conference on Robotics and Automation (ICRA) 2019, IEEE, International Conference on Robotics and Automation, May 2019
Grasping objects under uncertainty remains an open problem in robotics research. This uncertainty is often due to noisy or partial observations of the object pose or shape. To enable a robot to react appropriately to unforeseen effects, it is crucial that it continuously takes sensor feedback into account. While visual feedback is important for inferring a grasp pose and reaching for an object, contact feedback offers valuable information during manipulation and grasp acquisition. In this paper, we use model-free deep reinforcement learning to synthesize control policies that exploit contact sensing to generate robust grasping under uncertainty. We demonstrate our approach on a multi-fingered hand that exhibits more complex finger coordination than the commonly used two- fingered grippers. We conduct extensive experiments in order to assess the performance of the learned policies, with and without contact sensing. While it is possible to learn grasping policies without contact sensing, our results suggest that contact feedback allows for a significant improvement of grasping robustness under object pose uncertainty and for objects with a complex shape.
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Empirical Inference Conference Paper MYND: A Platform for Large-scale Neuroscientific Studies Hohmann, M. R., Hackl, M., Wirth, B., Zaman, T., Enficiaud, R., Grosse-Wentrup, M., Schölkopf, B. Proceedings of the 2019 Conference on Human Factors in Computing Systems (CHI), 1-6, Association for Computing Machinery, May 2019 DOI BibTeX
Autonomous Vision Conference Paper Project AutoVision: Localization and 3D Scene Perception for an Autonomous Vehicle with a Multi-Camera System Heng, L., Choi, B., Cui, Z., Geppert, M., Hu, S., Kuan, B., Liu, P., Nguyen, R. M. H., Yeo, Y. C., Geiger, A., Lee, G. H., Pollefeys, M., Sattler, T. In Proceedings of the IEEE International Conference on Robotics and Automation (ICRA) 2019, IEEE, International Conference on Robotics and Automation, May 2019
Project AutoVision aims to develop localization and 3D scene perception capabilities for a self-driving vehicle. Such capabilities will enable autonomous navigation in urban and rural environments, in day and night, and with cameras as the only exteroceptive sensors. The sensor suite employs many cameras for both 360-degree coverage and accurate multi-view stereo; the use of low-cost cameras keeps the cost of this sensor suite to a minimum. In addition, the project seeks to extend the operating envelope to include GNSS-less conditions which are typical for environments with tall buildings, foliage, and tunnels. Emphasis is placed on leveraging multi-view geometry and deep learning to enable the vehicle to localize and perceive in 3D space. This paper presents an overview of the project, and describes the sensor suite and current progress in the areas of calibration, localization, and perception.
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Autonomous Vision Conference Paper Real-Time Dense Mapping for Self-Driving Vehicles using Fisheye Cameras Cui, Z., Heng, L., Yeo, Y. C., Geiger, A., Pollefeys, M., Sattler, T. In Proceedings of the IEEE International Conference on Robotics and Automation (ICRA) 2019, IEEE, International Conference on Robotics and Automation, May 2019
We present a real-time dense geometric mapping algorithm for large-scale environments. Unlike existing methods which use pinhole cameras, our implementation is based on fisheye cameras which have larger field of view and benefit some other tasks including Visual-Inertial Odometry, localization and object detection around vehicles. Our algorithm runs on in-vehicle PCs at 15 Hz approximately, enabling vision-only 3D scene perception for self-driving vehicles. For each synchronized set of images captured by multiple cameras, we first compute a depth map for a reference camera using plane-sweeping stereo. To maintain both accuracy and efficiency, while accounting for the fact that fisheye images have a rather low resolution, we recover the depths using multiple image resolutions. We adopt the fast object detection framework YOLOv3 to remove potentially dynamic objects. At the end of the pipeline, we fuse the fisheye depth images into the truncated signed distance function (TSDF) volume to obtain a 3D map. We evaluate our method on large-scale urban datasets, and results show that our method works well even in complex environments.
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Haptic Intelligence Miscellaneous Toward Expert-Sourcing of a Haptic Device Repository Seifi, H., Ip, J., Agrawal, A., Kuchenbecker, K. J., MacLean, K. E. Workshop paper (5 pages) published at the CHI Workshop on Designing Crowd-powered Creativity Support Systems, Glasgow, UK, May 2019 (Published)
Haptipedia is an online taxonomy, database, and visualization that aims to accelerate ideation of new haptic devices and interactions in human-computer interaction, virtual reality, haptics, and robotics. The current version of Haptipedia (105 devices) was created through iterative design, data entry, and evaluation by our team of experts. Next, we aim to greatly increase the number of devices and keep Haptipedia updated by soliciting data entry and verification from haptics experts worldwide.
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Autonomous Learning Conference Paper Falsification of hybrid systems using symbolic reachability and trajectory splicing Bogomolov, S., Frehse, G., Gurung, A., Li, D., Martius, G., Ray, R. In Proceedings International Conference on Hybrid Systems: Computation and Control (HSCC ’19), 1-10, ACM, International Conference on Hybrid Systems: Computation and Control (HSCC '19), April 2019 (Published) Personal Copy DOI BibTeX
Probabilistic Numerics Empirical Inference Conference Paper Active Probabilistic Inference on Matrices for Pre-Conditioning in Stochastic Optimization de Roos, F., Hennig, P. Proceedings of the 22nd International Conference on Artificial Intelligence and Statistics (AISTATS), 89:1448-1457, (Editors: Kamalika Chaudhuri and Masashi Sugiyama), PMLR, April 2019 (Published)
Pre-conditioning is a well-known concept that can significantly improve the convergence of optimization algorithms. For noise-free problems, where good pre-conditioners are not known a priori, iterative linear algebra methods offer one way to efficiently construct them. For the stochastic optimization problems that dominate contemporary machine learning, however, this approach is not readily available. We propose an iterative algorithm inspired by classic iterative linear solvers that uses a probabilistic model to actively infer a pre-conditioner in situations where Hessian-projections can only be constructed with strong Gaussian noise. The algorithm is empirically demonstrated to efficiently construct effective pre-conditioners for stochastic gradient descent and its variants. Experiments on problems of comparably low dimensionality show improved convergence. In very high-dimensional problems, such as those encountered in deep learning, the pre-conditioner effectively becomes an automatic learning-rate adaptation scheme, which we also empirically show to work well.
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Haptic Intelligence Miscellaneous Bimanual Wrist-Squeezing Haptic Feedback Changes Speed-Force Tradeoff in Robotic Surgery Training Cao, E., Machaca, S., Bernard, T., Wolfinger, B., Patterson, Z., Chi, A., Adrales, G. L., Kuchenbecker, K. J., Brown, J. D. Extended abstract presented as an ePoster at the Annual Meeting of the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES), Baltimore, USA, April 2019 (Published) URL BibTeX
Intelligent Control Systems Poster Demo Abstract: Fast Feedback Control and Coordination with Mode Changes for Wireless Cyber-Physical Systems Mager, F., Baumann, D., Jacob, R., Thiele, L., Trimpe, S., Zimmerling, M. Proceedings of the 18th ACM/IEEE Conference on Information Processing in Sensor Networks (IPSN), 340-341, 18th ACM/IEEE Conference on Information Processing in Sensor Networks (IPSN), April 2019 (Published) arXiv PDF DOI BibTeX
Empirical Inference Conference Paper Fast Gaussian Process Based Gradient Matching for Parameter Identification in Systems of Nonlinear ODEs Wenk, P., Gotovos, A., Bauer, S., Gorbach, N., Krause, A., Buhmann, J. M. Proceedings of the 22nd International Conference on Artificial Intelligence and Statistics (AISTATS), 89:1351-1360, (Editors: Kamalika Chaudhuri and Masashi Sugiyama), PMLR, April 2019 (Published) PDF PDF URL BibTeX
Probabilistic Numerics Empirical Inference Conference Paper Fast and Robust Shortest Paths on Manifolds Learned from Data Arvanitidis, G., Hauberg, S., Hennig, P., Schober, M. Proceedings of the 22nd International Conference on Artificial Intelligence and Statistics (AISTATS), 89:1506-1515, (Editors: Kamalika Chaudhuri and Masashi Sugiyama), PMLR, April 2019 (Published) PDF URL BibTeX
Intelligent Control Systems Conference Paper Feedback Control Goes Wireless: Guaranteed Stability over Low-power Multi-hop Networks 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, 97-108, 10th ACM/IEEE International Conference on Cyber-Physical Systems, April 2019 (Published)
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.
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Haptic Intelligence Miscellaneous Interactive Augmented Reality for Robot-Assisted Surgery Forte, M., Kuchenbecker, K. J. Extended abstract presented as an Emerging Technology ePoster at the Annual Meeting of the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES), Baltimore, USA, April 2019 (Published) BibTeX
Movement Generation and Control Article Optimal Stair Climbing Pattern Generation for Humanoids Using Virtual Slope and Distributed Mass Model Shahrokhshahi, A., Yousefi-Koma, A., Khadiv, M., Mansouri, S., Mohtasebi, S. S. Journal of Intelligent and Robotics Systems, 94:1:43-59, April 2019 (Published) DOI BibTeX
Empirical Inference Conference Paper Resampled Priors for Variational Autoencoders Bauer, M., Mnih, A. Proceedings of the 22nd International Conference on Artificial Intelligence and Statistics (AISTATS), 89:66-75, Proceedings of Machine Learning Research, (Editors: Kamalika Chaudhuri and Masashi Sugiyama), PMLR, April 2019 (Published) arXiv URL BibTeX
Empirical Inference Article SPINDLE: End-to-end learning from EEG/EMG to extrapolate animal sleep scoring across experimental settings, labs and species Miladinovic, D., Muheim, C., Bauer, S., Spinnler, A., Noain, D., Bandarabadi, M., Gallusser, B., Krummenacher, G., Baumann, C., Adamantidis, A., Brown, S. A., Buhmann, J. M. PLOS Computational Biology, 15(4):article no. e1006968, Public Library of Science, April 2019 (Published) DOI URL BibTeX
Empirical Inference Conference Paper Semi-Generative Modelling: Covariate-Shift Adaptation with Cause and Effect Features von Kügelgen, J., Mey, A., Loog, M. In Proceedings of the 22nd International Conference on Artificial Intelligence and Statistics (AISTATS), 89:1361-1369, (Editors: Kamalika Chaudhuri and Masashi Sugiyama), PMLR, April 2019 (Published) PDF Poster URL BibTeX
Empirical Inference Conference Paper Sobolev Descent Mroueh, Y., Sercu, T., Raj, A. Proceedings of the 22nd International Conference on Artificial Intelligence and Statistics (AISTATS), 89:2976-2985, (Editors: Kamalika Chaudhuri and Masashi Sugiyama), PMLR, April 2019 (Published) PDF URL BibTeX
Micro, Nano, and Molecular Systems Article Self-Assembled Phage-Based Colloids for High Localized Enzymatic Activity Alarcon-Correa, M., Guenther, J., Troll, J., Kadiri, V. M., Bill, J., Fischer, P., Rothenstein, D. ACS Nano, 13:5810–5815, March 2019
Catalytically active colloids are model systems for chemical motors and active matter. It is desirable to replace the inorganic catalysts and the toxic fuels that are often used, with biocompatible enzymatic reactions. However, compared to inorganic catalysts, enzyme-coated colloids tend to exhibit less activity. Here, we show that the self-assembly of genetically engineered M13 bacteriophages that bind enzymes to magnetic beads ensures high and localized enzymatic activity. These phage-decorated colloids provide a proteinaceous environment for directed enzyme immobilization. The magnetic properties of the colloidal carrier particle permit repeated enzyme recovery from a reaction solution, while the enzymatic activity is retained. Moreover, localizing the phage-based construct with a magnetic field in a microcontainer allows the enzyme-phage-colloids to function as an enzymatic micropump, where the enzymatic reaction generates a fluid flow. This system shows the fastest fluid flow reported to date by a biocompatible enzymatic micropump. In addition, it is functional in complex media including blood where the enzyme driven micropump can be powered at the physiological blood-urea concentration.
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Haptic Intelligence Miscellaneous A Design Tool for Therapeutic Social-Physical Human-Robot Interactions Mohan, M., Kuchenbecker, K. J. 727-729, Workshop paper (3 pages) presented at the HRI Pioneers Workshop, Daegu, South Korea, March 2019 (Published)
We live in an aging society; social-physical human-robot interaction has the potential to keep our elderly adults healthy by motivating them to exercise. After summarizing prior work, this paper proposes a tool that can be used to design exercise and therapy interactions to be performed by an upper-body humanoid robot. The interaction design tool comprises a teleoperation system that transmits the operator’s arm motions, head motions and facial expression along with an interface to monitor and assess the motion of the user interacting with the robot. We plan to use this platform to create dynamic and intuitive exercise interactions.
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Haptic Intelligence Conference Paper 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 (Published)
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.
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Micro, Nano, and Molecular Systems Article Absolute diffusion measurements of active enzyme solutions by NMR Guenther, J., Majer, G., Fischer, P. J. Chem. Phys., 150(124201), March 2019
The diffusion of enzymes is of fundamental importance for many biochemical processes. Enhanced or directed enzyme diffusion can alter the accessibility of substrates and the organization of enzymes within cells. Several studies based on fluorescence correlation spectroscopy (FCS) report enhanced diffusion of enzymes upon interaction with their substrate or inhibitor. In this context, major importance is given to the enzyme fructose-bisphosphate aldolase, for which enhanced diffusion has been reported even though the catalysed reaction is endothermic. Additionally, enhanced diffusion of tracer particles surrounding the active aldolase enzymes has been reported. These studies suggest that active enzymes can act as chemical motors that self-propel and give rise to enhanced diffusion. However, fluorescence studies of enzymes can, despite several advantages, suffer from artefacts. Here we show that the absolute diffusion coefficients of active enzyme solutions can be determined with Pulsed Field Gradient Nuclear Magnetic Resonance (PFG-NMR). The advantage of PFG-NMR is that the motion of the molecule of interest is directly observed in its native state without the need for any labelling. Further, PFG-NMR is model-free and thus yields absolute diffusion constants. Our PFG-NMR experiments of solutions containing active fructose-bisphosphate aldolase from rabbit muscle do not show any diffusion enhancement for the active enzymes nor the surrounding molecules. Additionally, we do not observe any diffusion enhancement of aldolase in the presence of its inhibitor pyrophosphate.
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Perceiving Systems Conference Paper Distributed, Collaborative Virtual Reality Application for Product Development with Simple Avatar Calibration Method Dixken, M., Diers, D., Wingert, B., Hatzipanayioti, A., Mohler, B. J., Riedel, O., Bues, M. IEEE Conference on Virtual Reality and 3D User Interfaces, (VR), 1299-1300, IEEE, March 2019 (Published)
In this work we present a collaborative virtual reality application for distributed engineering tasks, including a simple avatar calibration method. Use cases for the application include CAD review, ergonomics analyses or virtual training. Full-body avatars with approximately natural motion characteristics are used to improve collaboration in terms of co-presence and embodiment. Through a calibration process, scaled avatars based on body measurements can be generated by users from within the VR application. For motion tracking, only the tracking capabilities of the VR devices used (head mounted display and hand controllers) are required, in order to achieve a low initialization effort for usage of the application. We demonstrate a simple, yet effective method for measuring the human body which requires these VR devices only. Tracking only the user's head and hands, we require inverse kinematics (IK) for avatar motion reconstruction. On the other hand, this requires a calibrated avatar, otherwise body postures and gestures will be misrepresented. In the first step of the demo, two users can create their calibrated avatar at the same time and then carry out a collaborative CAD review in the second step.
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Optics and Sensing Laboratory Article Elastic Scattering Time of Matter-Waves in Disordered Potentials Richard, J., Lim, L., Denechaud, V., Volchkov, V., Lecoutre, B., Mukhtar, M., Jendrzejewski, F., Aspect, A., Signoles, A., Sanchez-Palencia, L., Josse, V. Physical Review Letters, 122:100403, American Physical Society (APS), March 2019 (Published)
We report on an extensive study of the elastic scattering time $τ_\mathrm{s}$ of matter waves in optical disordered potentials. Using direct experimental measurements, numerical simulations, and comparison with the first-order Born approximation based on the knowledge of the disorder properties, we explore the behavior of $τ_\mathrm{s}$ over more than 3 orders of magnitude, ranging from the weak to the strong scattering regime. We study in detail the location of the crossover and, as a main result, we reveal the strong influence of the disorder statistics, especially on the relevance of the widely used Ioffe-Regel-like criterion $k l_\mathrm{s}\sim 1$. While it is found to be relevant for Gaussian-distributed disordered potentials, we observe significant deviations for laser speckle disorders that are commonly used with ultracold atoms. Our results are crucial for connecting experimental investigation of complex transport phenomena, such as Anderson localization, to microscopic theories.
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Physical Intelligence Article Elastic modulus affects adhesive strength of gecko-inspired synthetics in variable temperature and humidity Mitchell, C. T., Drotlef, D., Dayan, C. B., Sitti, M., Stark, A. Y. Integrative and Comparative Biology, 59(Supplement 1):E372-E372, March 2019 DOI BibTeX
Conference Paper Obstacles Awareness Methods from Occupancy Map for Free Walking in VR Keller, M., Tchilinguirian, T. In Proceedings IEEE Conference on Virtual Reality and 3D User Interfaces (VR) , 1012-1013, IEEE, 2019 IEEE Conference on Virtual Reality and 3D User Interfaces (VR), March 2019
With Head Mounted Displays (HMD) equipped with extended tracking features, users can now walk in a room scale space while being immersed in a virtual world. However, to fully exploit this feature and enable free-walking, these devices still require a large physical space, cleared of obstacles. This is an essential requirement that not any user can meet, especially at home, thus this constraint limits the use of free-walking in Virtual Reality (VR) applications. In this poster, we propose ways of representing the physical obstacles surrounding the user. There are generated from an occupancy map and compared to the representation as a point cloud. We propose three visualisation modes: integrating an occupancy map into the virtual floor, generating lava lakes where obstacles are and building a semi-transparent wall along the obstacles boundaries. We found that although showing the obstacles on the floor only impacts lightly the navigation, the preferred visualization mode remains the point cloud.
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Physical Intelligence Article Programmable collective behavior in dynamically self‐assembled mobile microrobotic swarms Berk Yigit, Y. A. M. S. Advanced Science, 6(6):1801837, March 2019 DOI BibTeX
Micro, Nano, and Molecular Systems Article Chemical Nanomotors at the Gram Scale Form a Dense Active Optorheological Medium Choudhury, U., Singh, D. P., Qiu, T., Fischer, P. Adv. Mat., 31(1807382), February 2019
The rheological properties of a colloidal suspension are a function of the concentration of the colloids and their interactions. While suspensions of passive colloids are well studied and have been shown to form crystals, gels, and glasses, examples of energy‐consuming “active” colloidal suspensions are still largely unexplored. Active suspensions of biological matter, such as motile bacteria or dense mixtures of active actin–motor–protein mixtures have, respectively, reveals superfluid‐like and gel‐like states. Attractive inanimate systems for active matter are chemically self‐propelled particles. It has so far been challenging to use these swimming particles at high enough densities to affect the bulk material properties of the suspension. Here, it is shown that light‐triggered asymmetric titanium dioxide that self‐propel, can be obtained in large quantities, and self‐organize to make a gram‐scale active medium. The suspension shows an activity‐dependent tenfold reversible change in its bulk viscosity.
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Perceiving Systems Article Perceptual Effects of Inconsistency in Human Animations Kenny, S., Mahmood, N., Honda, C., Black, M. J., Troje, N. F. ACM Trans. Appl. Percept., 16(1):2:1-2:18, February 2019
The individual shape of the human body, including the geometry of its articulated structure and the distribution of weight over that structure, influences the kinematics of a person’s movements. How sensitive is the visual system to inconsistencies between shape and motion introduced by retargeting motion from one person onto the shape of another? We used optical motion capture to record five pairs of male performers with large differences in body weight, while they pushed, lifted, and threw objects. From these data, we estimated both the kinematics of the actions as well as the performer’s individual body shape. To obtain consistent and inconsistent stimuli, we created animated avatars by combining the shape and motion estimates from either a single performer or from different performers. Using these stimuli we conducted three experiments in an immersive virtual reality environment. First, a group of participants detected which of two stimuli was inconsistent. Performance was very low, and results were only marginally significant. Next, a second group of participants rated perceived attractiveness, eeriness, and humanness of consistent and inconsistent stimuli, but these judgements of animation characteristics were not affected by consistency of the stimuli. Finally, a third group of participants rated properties of the objects rather than of the performers. Here, we found strong influences of shape-motion inconsistency on perceived weight and thrown distance of objects. This suggests that the visual system relies on its knowledge of shape and motion and that these components are assimilated into an altered perception of the action outcome. We propose that the visual system attempts to resist inconsistent interpretations of human animations. Actions involving object manipulations present an opportunity for the visual system to reinterpret the introduced inconsistencies as a change in the dynamics of an object rather than as an unexpected combination of body shape and body motion.
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Intelligent Control Systems Ph.D. Thesis Fast and Resource-Efficient Control of Wireless Cyber-Physical Systems Baumann, D. KTH Royal Institute of Technology, Stockholm, February 2019 (Published) PDF BibTeX
Empirical Inference Ph.D. Thesis Learning Transferable Representations Rojas-Carulla, M. University of Cambridge, UK, February 2019 (Published) BibTeX
Empirical Inference Probabilistic Learning Group Conference Paper Automatic Bayesian Density Analysis Vergari, A., Molina, A., Peharz, R., Ghahramani, Z., Kersting, K., Valera, I. Proceedings of the AAAI Conference on Artificial Intelligence (AAAI-19), 33:01, 5207-5215, AAAI.org, AAAI-19, January 2019 (Published) arXiv DOI BibTeX
Micro, Nano, and Molecular Systems Article First Observation of Optical Activity in Hyper-Rayleigh Scattering Collins, J., Rusimova, K., Hooper, D., Jeong, H. H., Ohnoutek, L., Pradaux-Caggiano, F., Verbiest, T., Carbery, D., Fischer, P., Valev, V. Phys. Rev. X, 9(011024), January 2019
Chiral nano- or metamaterials and surfaces enable striking photonic properties, such as negative refractive index and superchiral light, driving promising applications in novel optical components, nanorobotics, and enhanced chiral molecular interactions with light. In characterizing chirality, although nonlinear chiroptical techniques are typically much more sensitive than their linear optical counterparts, separating true chirality from anisotropy is a major challenge. Here, we report the first observation of optical activity in second-harmonic hyper-Rayleigh scattering (HRS). We demonstrate the effect in a 3D isotropic suspension of Ag nanohelices in water. The effect is 5 orders of magnitude stronger than linear optical activity and is well pronounced above the multiphoton luminescence background. Because of its sensitivity, isotropic environment, and straightforward experimental geometry, HRS optical activity constitutes a fundamental experimental breakthrough in chiral photonics for media including nanomaterials, metamaterials, and chemical molecules.
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Physical Intelligence MPI Year Book "Jellyfishbot"- Ein Schwimmroboter inspiriert von Quallen / Scientists invent jellyfish-inspired swimming robot “Jellyfishbot” Ren, Z., Hu, W., Dong, X., Sitti, M. January 2019 (Published)
Am Max-Planck-Instituts für Intelligente Systeme in Stuttgart entwickeln wir einen Roboter, der wie eine Qualle aussieht und sich auch so bewegt: den "Jellyfishbot". Der nicht kabelgebundene Roboter verfügt wie sein natürliches Vorbild über eine schirmförmige Glocke und nachziehende Tentakel. Die Forschungsarbeit birgt großes Potenzial, sowohl die Auswirkungen von Umweltveränderungen auf die Ökosysteme der Ozeane zu untersuchen als auch die Behandlung von Krebs zu revolutionieren. ENGLISH: At the Max Planck Institute for Intelligent Systems in Stuttgart we develop a robot that looks and moves like a jellyfish, one of the world’s most common marine animals: the “jellyfishbot”. The untethered robot features an umbrella-shaped bell and trailing tentacles just like its natural model. The research holds great potential when investigating the impact of environmental changes on the oceans’ ecosystems. Another vision for the jellyfishbot is to revolutionize the treatment of cancer. Den gesamten Forschungsbeitrag finden Sie auf der Homepage der Max-Planck-Gesellschaft.
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Perceiving Systems MPI Year Book Colour patch could throw self-driving vehicles off track Ranjan, A., Janai, J., Geiger, A., Black, M. J. January 2019 (Published)
In our team of researchers at the Max-Planck-Institute for Intelligent Systems in Tübingen we show that optical flow systems based on deep neural networks – a likely component of future autonomous cars – are vulnerable to adversarial attacks. The computer vision experts are shaking up the automotive industry by warning car manufacturers around the globe that it could take a simple color pattern to put the brakes on computer vision systems in autonomous cars. The full article can be read on the website of the Max Planck Society.
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Theory of Inhomogeneous Condensed Matter Article Active rotational dynamics of a self-diffusiophoretic colloidal motor Reigh, S., Huang, M., Löwen, H., Lauga, E., Kapral, R. Soft Matter, 16(5):1236-1245, 2019 (Published) DOI BibTeX
Physical Intelligence Article 3D-printed biodegradable microswimmer for theranostic cargo delivery and release Ceylan, H., Yasa, I. C., Yasa, O., Tabak, A. F., Giltinan, J., Sitti, M. ACS Nano, 13(3):3353-3362, ACS Publications, 2019 BibTeX
Physical Intelligence Article 3D‐printed microrobotic transporters with recapitulated stem cell niche for programmable and active cell delivery Yasa, I. C., Tabak, A. F., Yasa, O., Ceylan, H., Sitti, M. Advanced Functional Materials, 29(17):1808992, 2019 DOI BibTeX
Article A Distributed ADMM Approach to Non-Myopic Path Planning for Multi-Target Tracking Park, S., Min, Y., Ha, J., Cho, D., Choi, H. IEEE Access, 7:163589-163603, IEEE, New York, NY, 2019 DOI BibTeX
Movement Generation and Control Article A Robustness Analysis of Inverse Optimal Control of Bipedal Walking Rebula, J. R., Schaal, S., Finley, J., Righetti, L. IEEE Robotics and Automation Letters, 4(4):4531-4538, 2019 (Published) DOI BibTeX
Physical Intelligence Conference Paper A bio-inspired robotic fish fin with mechanosensation using conductive liquid-metal-infused soft actuators Liu, Z., Sun, W., Ren, Z., Hu, K., Wang, T., Wen, L. 2019 IEEE 9th Annual International Conference on CYBER Technology in Automation, Control, and Intelligent Systems (CYBER 2019), 689-694, IEEE, Piscataway, NJ, IEEE 9th Annual International Conference on CYBER Technology in Automation, Control, and Intelligent Systems (CYBER 2019) , 2019 (Published) DOI URL BibTeX
Physical Intelligence Article A force-measuring and behaviour-recording system consisting of 24 individual 3D force plates for the study of single limb forces in climbing animals on a quasi-cylindrical tower Ji, A., Yuan, S., Endlein, T., Hill, I. D., Wang, W., Wang, H., Jiang, N., Zhao, Z., Barnes, W. J. P., Dai, Z. Bioinspiration \& biomimetics, 14(4):046004, IOP Publishing, 2019 BibTeX
Physical Intelligence Article A general electromechanical model for plates with integrated piezo-patches using spectral-Tchebychev method Aghakhani, A., Motlagh, P. L., Bediz, B., Basdogan, I. Journal of Sound and Vibration, 458:74-88, Elsevier, 2019 BibTeX
Physical Intelligence Patent A liquid repellent fibrillar dry adhesive material and a method of producing the same Sitti, M., Liimatainen, V. 2019, EP Patent App. 19 218 616.1, Dec.2019 BibTeX