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Institute Talks

"Exploring” Haptics: Human-Machine Interactive Applications from Mid-Air Laser Haptics to Sensorimotor Skill Learning

  • 25 February 2019 • 10:30 11:15
  • Hojin Lee
  • MPI-IS Stuttgart, Heisenbergstr. 3, Room 2P4

Haptic technologies in both kinesthetic and tactile aspects benefit a brand-new opportunity to recent human-machine interactive applications. In this talk, I, who believe in that one of the essential role of a researcher is pioneering new insights and knowledge, will present my previous research topics about haptic technologies and human-machine interactive applications in two branches: laser-based mid-air haptics and sensorimotor skill learning. For the former branch, I will introduce our approach named indirect laser radiation and its application. Indirect laser radiation utilizes a laser and a light-absorbing elastic medium to evoke a tapping-like tactile sensation. For the latter, I will introduce our data-driven approach for both modeling and learning of sensorimotor skills (especially, driving) with kinesthetic assistance and artificial neural networks; I call it human-like haptic assistance. To unify two different branches of my earlier studies for exploring the feasibility of the sensory channel named "touch", I will present a general research paradigm for human-machine interactive applications to which current haptic technologies can aim in future.

Organizers: Katherine J. Kuchenbecker

Virtual Reality Based Needle Insertion Simulation With Haptic Feedback: A Psychophysical Study

  • 25 February 2019 • 11:15 12:00
  • Ravali Gourishetti
  • MPI-IS Stuttgart, Heisenbergstr. 3, Room 2P4

Needle insertion is the most essential skill in medical care; training has to be imparted not only for physicians but also for nurses and paramedics. In most needle insertion procedures, haptic feedback from the needle is the main stimulus that novices are to be trained in. For better patient safety, the classical methods of training the haptic skills have to be replaced with simulators based on new robotic and graphics technologies. The main objective of this work is to develop analytical models of needle insertion (a special case of epidural anesthesia) including the biomechanical and psychophysical concepts that simulate the needle-tissue interaction forces in linear heterogeneous tissues and to validate the model with a series of experiments. The biomechanical and perception models were validated with experiments in two stages: with and without the human intervention. The second stage is the validation using the Turing test with two different experiments: 1) to observe the perceptual difference between the simulated and the physical phantom model, and 2) to verify the effectiveness of perceptual filter between the unfiltered and filtered model response. The results showed that the model could replicate the physical phantom tissues with good accuracy. This can be further extended to a non-linear heterogeneous model. The proposed needle/tissue interaction force models can be used more often in improving realism, performance and enabling future applications in needle simulators in heterogeneous tissue. Needle insertion training simulator was developed with the simulated models using Omni Phantom and clinical trials are conducted for the face validity and construct validity. The face validity results showed that the degree of realism of virtual environments and instruments had the overall lowest mean score and ease of usage and training in hand – eye coordination had the highest mean score. The construct validity results showed that the simulator was able to successfully differentiate force and psychomotor signatures of anesthesiologists with experiences less than 5 years and more than 5 years. For the performance index of the trainees, a novel measure, Just Controllable Difference (JCD) was proposed and a preliminary study on JCD measure is explored using two experiments for the novice. A preliminary study on the use of clinical training simulations, especially needle insertion procedure in virtual environments is emphasized on two objectives: Firstly, measures of force JND with the three fingers and secondly, comparison of these measures in Non-Immersive Virtual Reality (NIVR) to that of the Immersive Virtual Reality (IVR) using psychophysical study with the Force Matching task, Constant Stimuli method, and Isometric Force Probing stimuli. The results showed a better force JND in the IVR compared to that of the NIVR. Also, a simple state observer model was proposed to explain the improvement of force JND in the IVR. This study would quantitatively reinforce the use of the IVR for the design of various medical simulators.

Organizers: Katherine J. Kuchenbecker

Design of functional polymers for biomedical applications

  • 27 February 2019 • 14:00 15:00
  • Dr. Salvador Borrós Gómez
  • Stuttgart 2P4

Functional polymers can be easily tailored for their interaction with living organismes. In our Group, we have worked during the last 15 years in the development of this kind of polymeric materials with different funcionalities, high biocompatibility and in different forms. In this talk, we will describe the synthesis of thermosensitive thin films that can be used to prevent biofilm formation in medical devices, the preparation of biodegradable polymers specially designed for vectors for gene transfection and a new familliy of zwitterionic polymers that are able to cross intestine mucouse for oral delivery applications. The relationship between structure-functionality- applications will be discussed for every example.

Organizers: Metin Sitti

A new path to understanding biological/human vision: theory and experiments

IS Colloquium
  • 11 March 2019 • 14:00 15:00
  • Zhaoping Li
  • MPI-IS lecture hall (N0.002)

Since Hubel and Wiesel's seminal findings in the primary visual cortex (V1) more than 50 years ago, progress in vision science has been very limited along previous frameworks and schools of thoughts on understanding vision. Have we been asking the right questions? I will show observations motivating the new path. First, a drastic information bottleneck forces the brain to process only a tiny fraction of the massive visual input information; this selection is called the attentional selection, how to select this tiny fraction is critical. Second, a large body of evidence has been accumulating to suggest that the primary visual cortex (V1) is where this selection starts, suggesting that the visual cortical areas along the visual pathway beyond V1 must be investigated in light of this selection in V1. Placing attentional selection as the center stage, a new path to understanding vision is proposed (articulated in my book "Understanding vision: theory, models, and data", Oxford University Press 2014). I will show a first example of using this new path, which aims to ask new questions and make fresh progresses. I will relate our insights to artificial vision systems to discuss issues like top-down feedbacks in hierachical processing, analysis-by-synthesis, and image understanding.

Organizers: Timo Bolkart Aamir Ahmad

  • Silvia Zuffi
  • N3.022

Animals are widespread in nature and the analysis of their shape and motion is of importance in many fields and industries. Modeling 3D animal shape, however, is difficult because the 3D scanning methods used to capture human shape are not applicable to wild animals or natural settings. In our previous SMAL model, we learn animal shape from toys figurines, but toys are limited in number and realism, and not every animal is sufficiently popular for there to be realistic toys depicting it. What is available in large quantities are images and videos of animals from nature photographs, animal documentaries, and webcams. In this talk I will present our recent work for capturing the detailed 3D shape of animals from images alone. Our method extracts significantly more 3D shape detail than previous work and is able to model new species using only a few video frames. Additionally, we extract realistic texture map from images for capturing both animal shape and appearance.

  • Sergio Pascual Díaz
  • S2.014

My plan is to present the motivation behind Deep GPs as well as some of the current approximate inference schemes available with their limitations. Then, I will explain how Deep GPs fit into the BayesOpt framework and the specific problems they could potentially solve.

Organizers: Philipp Hennig

  • Patrick Bajari
  • MPI IS lecture hall (N0.002)

In academic and policy circles, there has been considerable interest in the impact of “big data” on firm performance. We examine the question of how the amount of data impacts the accuracy of Machine Learned models of weekly retail product forecasts using a proprietary data set obtained from Amazon. We examine the accuracy of forecasts in two relevant dimensions: the number of products (N), and the number of time periods for which a product is available for sale (T). Theory suggests diminishing returns to larger N and T, with relative forecast errors diminishing at rate 1/sqrt(N) + 1/sqrt(T) . Empirical results indicate gains in forecast improvement in the T dimension; as more and more data is available for a particular product, demand forecasts for that product improve over time, though with diminishing returns to scale. In contrast, we find an essentially flat N effect across the various lines of merchandise: with a few exceptions, expansion in the number of retail products within a category does not appear associated with increases in forecast performance. We do find that the firm’s overall forecast performance, controlling for N and T effects across product lines, has improved over time, suggesting gradual improvements in forecasting from the introduction of new models and improved technology.

Organizers: Michel Besserve Michael Hirsch

Political Science and Data Science: What we can learn from each other

IS Colloquium
  • 12 March 2018 • 11:15 12:15
  • Simon Hegelich
  • MPI-IS lecture hall (N0.002)

Political science is integrating computational methods like machine learning into its own toolbox. At the same time the awareness rises that the utilization of machine learning algorithms in our daily life is a highly political issue. These two trends - the integration of computational methods into political science and the political analysis of the digital revolution - form the ground for a new transdisciplinary approach: political data science. Interestingly, there is a rich tradition of crossing the borders of the disciplines, as can be seen in the works of Paul Werbos and Herbert Simon (both political scientists). Building on this tradition and integrating ideas from deep learning and Hegel's philosophy of logic a new perspective on causality might arise.

Organizers: Philipp Geiger

  • Giacomo Garegnani
  • Tübingen, S2 seminar room

We present a novel probabilistic integrator for ordinary differential equations (ODEs) which allows for uncertainty quantification of the numerical error [1]. In particular, we randomise the time steps and build a probability measure on the deterministic solution, which collapses to the true solution of the ODE with the same rate of convergence as the underlying deterministic scheme. The intrinsic nature of the random perturbation guarantees that our probabilistic integrator conserves some geometric properties of the deterministic method it is built on, such as the conservation of first integrals or the symplecticity of the flow. Finally, we present a procedure to incorporate our probabilistic solver into the frame of Bayesian inference inverse problems, showing how inaccurate posterior concentrations given by deterministic methods can be corrected by a probabilistic interpretation of the numerical solution.

Organizers: Hans Kersting

  • Bin Yu
  • Tübingen, IS Lecture Hall (N0.002)

In this talk, I'd like to discuss the intertwining importance and connections of three principles of data science in the title. They will be demonstrated in the context of two collaborative projects in neuroscience and genomics, respectively. The first project in neuroscience uses transfer learning to integrate fitted convolutional neural networks (CNNs) on ImageNet with regression methods to provide predictive and stable characterizations of neurons from the challenging primary visual cortex V4. The second project proposes iterative random forests (iRF) as a stablized RF to seek predictable and interpretable high-order interactions among biomolecules.

Organizers: Michel Besserve

  • Prof. Constantin Rothkopf
  • Tübingen, 3rd Floor Intelligent Systems: Aquarium

Active vision has long put forward the idea, that visual sensation and our actions are inseparable, especially when considering naturalistic extended behavior. Further support for this idea comes from theoretical work in optimal control, which demonstrates that sensing, planning, and acting in sequential tasks can only be separated under very restricted circumstances. The talk will present experimental evidence together with computational explanations of human visuomotor behavior in tasks ranging from classic psychophysical detection tasks to ball catching and visuomotor navigation. Along the way it will touch topics such as the heuristics hypothesis and learning of visual representations. The connecting theme will be that, from the switching of visuomotor behavior in response to changing task-constraints down to cortical visual representations in V1, action and perception are inseparably intertwined in an ambiguous and uncertain world

Organizers: Betty Mohler

A naturalistic perspective on optic flow processing in the fly

  • 27 February 2018 • 3:00 p.m. 4:00 p.m.
  • Aljoscha Leonhardt
  • N4.022, EI Glass Seminar Room

Optic flow offers a rich source of information about an organism’s environment. Flies, for instance, are thought to make use of motion vision to control and stabilise their course during acrobatic airborne manoeuvres. How these computations are implemented in neural hardware and how such circuits cope with the visual complexity of natural scenes, however, remain open questions. This talk outlines some of the progress we have made in unraveling the computational substrate underlying optic flow processing in Drosophila. In particular, I will focus on our efforts to connect neural mechanisms and real-world demands via task-driven modelling.

Organizers: Michel Besserve

Patient Inspired Engineering: Problem, device, solution

  • 26 February 2018 • 11:00 12:00
  • Professor Rahmi Oklu
  • Room 3P02 - Stuttgart

Minimally invasive approaches to the treatment of vascular diseases are constantly evolving. These diseases are among the most prevalent medical problems today including stroke, myocardial infarction, pulmonary emboli, hemorrhage and aneurysms. I will review current approaches to vascular embolization and thrombosis, the challenges they pose and the limitations of current devices and end with patient inspired engineering approaches to the treatment of these conditions.

Organizers: Metin Sitti

Deriving a Tongue Model from MRI Data

  • 20 February 2018 • 14:00 14:45
  • Alexander Hewer
  • Aquarium

The tongue plays a vital part in everyday life where we use it extensively during speech production. Due to this importance, we want to derive a parametric shape model of the tongue. This model enables us to reconstruct the full tongue shape from a sparse set of points, like for example motion capture data. Moreover, we can use such a model in simulations of the vocal tract to perform articulatory speech synthesis or to create animated virtual avatars. In my talk, I describe a framework for deriving such a model from MRI scans of the vocal tract. In particular, this framework uses image denoising and segmentation methods to produce a point cloud approximating the vocal tract surface. In this context, I will also discuss how palatal contacts of the tongue can be handled, i.e., situations where the tongue touches the palate and thus no tongue boundary is visible. Afterwards, template matching is used to derive a mesh representation of the tongue from this cloud. The acquired meshes are finally used to construct a multilinear model.

Organizers: Timo Bolkart