MPC-basierte Bewegungsplanung für Fahrsimulatoren mit echtzeitfähiger Fahrerprädiktion

The usage of human-centered motion simulation systems has been a significant component of the research and development process in various fields for many years. The predominant areas of application are in flight and driving simulation, where such systems are used for the testing of new components or setups as well as for pilot and driver training. The reasons for using a simulator rather than performing an experiment in the real world are safety, time and cost efficiency, as well as the perfectly controllable and reproducible experiment conditions. Independent of the particular application, the level of immersion for a test person in the simulator is crucial in order to be able to transfer the results from simulator experiments to the real world. Thus, modern motion simulation systems are equipped with various immersion systems including a visual system for environment representation, an audio system for noise simulations as well as a motion system to reproduce the real world forces. This thesis focuses on the motion planning for dynamic driving simulators, i.e. the reproduction of the physical accelerations and angular velocities acting on a driver in a real vehicle with the motion system of the simulator. The key challenges in this regard are the constrained motion space of technical simulation systems when compared to the practically unlimited motion space of a vehicle in the real world as well as the hard real-time constraint in combination with small sampling times of typically 1-10 ms for the online driver-in-the-loop application of the motion controller. Traditionally, the algorithms used for the motion planning of dynamic driving simulators, the so-called motion cueing algorithms (MCA), are based on a combination of linear, time-invariant high- and lowpass filters. These state-of-the-art approaches have some clear disadvantages such as the inability to directly incorporate the simulation system limitations into the motion planning or the incapability of dynamically prepositioning the simulator in order to increase the motion space for oncoming maneuvers. With the goal to resolve the key motion cueing challenges and to overcome the main disadvantages of the state-of-the-art filter-based approaches, a motion cueing algorithm based on nonlinear model predictive control (MPC) is developed in the context of this thesis. The key idea is to formulate the motion cueing problem as a dynamical optimization problem over a moving time horizon, which is iteratively solved at every sampling step. The underlying problem formulation includes a suitable cost function to reach the motion cueing control objective and is constraint by the system dynamics as well as the actuator limitations of the used simulator geometry. The derived control scheme is applicable to various simulator geometries and is especially suited to exploit redundant degrees of freedom in simulation systems. In order to fully exploit the predictive potential of the derived control approach in the online driver-in-the-loop application, an algorithm to predict the future driver behavior and consequently the future desired values for the MPC-based motion cueing algorithm is developed. The approach models the human driver as an optimal controller with the goal to follow a predefined reference route. Through this prediction approach, the controller is able to dynamically preposition the the simulator based on future maneuvers in order to increase the available motion space for their reproduction. Since different human drivers in general perform similar control actions when confronted with the same driving situation or task, learning-based methods are employed in order to further increase the accuracy of the predicted future driving actions. In this thesis, learning-based approaches are used for an automated tuning of the control-based prediction method as well as for the development of a purely data-driven prediction method based on neural networks. In order to be able to use the overall control scheme in the actual online driver-in-the-loop context, an efficient method for the numerical solution of the motion cueing as well as the driver prediction optimal control problems has to be used. In this thesis, an augmented Lagrangian approach to incorporate the nonlinear, state-dependent constraints in combination with a real-time capable projected gradient algorithm is employed. Objective evaluations as well as the subjective comparison of the newly developed overall control scheme to a filter-based approach by means of an online simulator experiment show the huge potential of the newly developed method when compared to the state-of-the-art MCA. Furthermore, the results show the broad applicability of the developed control scheme for various different use cases, including standard driving, driving dynamics applications as well as racetrack simulations. Finally, a run-time analysis demonstrates the efficiency of the employed numerical solution method and shows the real-time feasibility of the overall control scheme consisting of driver prediction and MPC-based motion cueing algorithm.Der Einsatz von Bewegungssimulationssystemen für Experimente mit menschlichen Probanden ist seit vielen Jahren ein wichtiger Bestandteil des Forschungs- und Entwicklungsprozesses in vielen Bereichen. Die vorherrschenden Anwendungsgebiete sind dabei die Flug- und Fahrsimulation, wo derartige Systeme für die Erprobung neuer Komponenten oder Einstellungen sowie für das Piloten- und Fahrertraining eingesetzt werden. Die Hauptgründe, ein Experiment in einem Simulator statt in der realen Welt durchzuführen, sind Sicherheit, Zeit- und Kosteneffizienz sowie die perfekt kontrollierbaren und reproduzierbaren Versuchsbedingungen. Unabhängig von der jeweiligen Anwendung ist es entscheidend, bei einer Testperson im Simulator einen möglichst realitätsnahen Gesamteindruck zu erzeugen, um die Ergebnisse aus Simulator-Experimenten in die reale Welt übertragen zu können. Moderne Bewegungssimulationssysteme sind daher mit verschiedenen Immersionssystemen ausgestattet, darunter ein visuelles System zur Umgebungsdarstellung, ein Audiosystem für Geräuschsimulationen sowie ein Bewegungssystem zur Reproduktion der in der Realität wirkenden physikalischen Kräfte. Der Fokus dieser Arbeit liegt auf der Bewegungsplanung für dynamische Fahrsimulatoren, d.h. der Nachbildung der physikalischen Beschleunigungen und Winkelgeschwindigkeiten, die auf einen Fahrer in einem realen Fahrzeug wirken, mit dem Bewegungssystem des Simulators. Die zentralen Herausforderungen sind dabei der stark eingeschränkte Bewegungsraum technischer Simulationssysteme im Vergleich zum praktisch unbegrenzten Bewegungsraum eines Fahrzeugs in der realen Welt sowie die harte Echtzeitanforderung in Kombination mit kleinen Abtastzeiten von typischerweise 1-10 ms für die Online-Anwendung. Traditionell bestehen die für die Bewegungsplanung von dynamischen Fahrsimulatoren verwendeten Algorithmen, die sogenannten Motion Cueing-Algorithmen (MCA), aus einer Kombination von linearen, zeitinvarianten Hoch- und Tiefpassfiltern. Diese Ansätze haben einige klare Nachteile. Beispielsweise können die Beschränkungen des Simulationssystems nicht direkt in der Bewegungsplanung berücksichtigt werden. Ebenso ist es nicht möglich, den Simulator dynamisch vorzupositionieren, um so den Bewegungsraum für bevorstehende Manöver zu vergrößern. Mit dem Ziel, die wichtigsten Herausforderungen des Motion Cueings anzugehen und die Hauptnachteile der filterbasierten Ansätze zu überwinden, wird im Rahmen dieser Arbeit ein Motion Cueing-Algorithmus basierend auf der nichtlinearen modellprädiktiven Regelung (MPC) entwickelt. Die Grundidee dabei besteht darin, das Motion Cueing-Problem als ein dynamisches Optimierungsproblem über einen bewegten Zeithorizont zu formulieren, das in jedem Abtastschritt iterativ gelöst wird. Die zugrundeliegende Problemformulierung beinhaltet eine geeignete Kostenfunktion zur Erreichung des Motion Cueing-Kontrollziels unter Berücksichtigung der Systemdynamik und der Aktorbeschränkungen der verwendeten Simulatorgeometrie. Der entwickelte Bewegungsplanungsansatz ist in Kombination mit verschiedenen Simulatorgeometrien anwendbar und eignet sich insbesondere zur Ausnutzung redundanter Freiheitsgrade in Simulationssystemen. Um das prädiktive Potenzial des entwickelten Bewegungsplanungsverfahrens in der Online-Anwendung voll ausnutzen zu können, wird ein Algorithmus zur Prädiktion des zukünftigen menschlichen Fahrerverhaltens und folglich der zukünftigen Sollwerte für den MPC-basierten Motion Cueing-Algorithmus entwickelt. Der Ansatz modelliert den menschlichen Fahrer als einen optimierungsbasierten Regler mit dem Ziel, einer vordefinierten Referenzroute zu folgen. Durch diesen Prädiktionsalgorithmus ist der entwickelte MCA in der Lage, den Simulator auf der Grundlage zukünftiger Manöver dynamisch vorzupositionieren, um so den verfügbaren Bewegungsraum für deren Reproduktion zu vergrößern. Da verschiedene menschliche Fahrer in der Regel ähnlich agieren, wenn sie mit der gleichen Fahrsituation konfrontiert sind, ist es möglich, lernbasierte Methoden zu verwenden, um die Genauigkeit der vorhergesagten zukünftigen Fahraktionen weiter zu erhöhen. In dieser Arbeit werden die lernbasierten Ansätze sowohl für eine automatisierte Parametrierung der reglerbasierten Prädiktionsmethode als auch für die Entwicklung einer rein datengetriebenen Vorhersagemethode auf der Basis neuronaler Netze verwendet. Um den Gesamtalgorithmus in der Online-Anwendung nutzen zu können, muss eine effiziente Methode zur numerischen Lösung der dynamischen Optimierungsprobleme für das Motion Cueing sowie für die Fahrerprädiktion gewählt werden. In dieser Arbeit wird ein erweiterter Lagrange-Ansatz zur Einbeziehung der nichtlinearen, zustandsabhängigen Beschränkungen in Kombination mit einem echtzeitfähigen projizierten Gradientenverfahren verwendet. Objektive Auswertungen sowie der subjektive Vergleich des neu entwickelten Bewegungsplanungsalgorithmus mit einem filterbasierten Ansatz mittels eines online Simulator-Experiments zeigen das große Potenzial des neu entwickelten Verfahrens im Vergleich zu den filterbasierten Ansätzen. Darüber hinaus zeigen die Ergebnisse die breite Anwendbarkeit des entwickelten MCAs für verschiedene Anwendungsfälle, darunter Standardfahrten, Fahrdynamikanwendungen sowie Rennstreckensimulationen. Abschließend zeigt eine Laufzeitanalyse die Effizienz der verwendeten numerischen Lösungsmethode und demonstriert die Echtzeitfähigkeit des Gesamtverfahrens bestehend aus Fahrerprädiktion und MPC-basiertem Motion Cueing-Algorithmus

Acoustic Pressure Pipette Aspiration Method Combined with Finite Element Analysis for Isotropic Materials

A measurement setup combined with a numerical simulation by a linear finite element analysis is presented as a method to determine the elastic modulus of both artificial and real tissue as a function of frequency. At the end, the future goal is to develop and validate the method to measure the elastic modulus of in-vivo human vocal folds over the human phonation frequency range. In the present study, a miniaturized acoustic pressure pipette aspiration technique is developed to measure the material characteristics of an isotropic silicone specimen with similar characteristics as human vocal folds. In previous studies, friction and compression force effects of the pipette tip wall on the surface of the sample and the radius of the pipette were not investigated. Moreover, the large scale of the measurement setups made them impossible to use for clinical applications. Therefore, two different pipette sample cross-section boundary conditions and two different pipette radii were used. With the aim of ensuring reliable results, we tested our method with pipettes of two different radii on four silicone samples with different consistencies over a frequency range of 50–500 Hz. The simulation verified the measurement results in which the strong dependency of the elastic modulus on the excitation frequency, radius of the pipette, the pipette tip compression force and friction was revealed. By the simulation results, two different frequency dependent equations were developed for calculating elastic modulus of the silicone mixtures in the two cross-section boundary conditions. It was concluded that using a very small gap in between the pipette tip and the specimen can cancel the impact of the pipette tip force and friction which are the major cause of uncertainty. However, if a connection between the pipette and the surface is unpreventable, the contact force should be restricted to be absolutely zero

Dynamic Biomechanical Analysis of Vocal Folds Using Pipette Aspiration Technique

The voice producing process is a complex interplay between glottal pressure, vocal folds, their elasticity and tension. The material properties of vocal folds are still insufficiently studied, because the determination of material properties in soft tissues is often difficult and connected to extensive experimental setups. To shed light on this less researched area, in this work, a dynamic pipette aspiration technique is utilized to measure the elasticity in a frequency range of 100–1000 Hz. The complex elasticity could be assessed with the phase shift between exciting pressure and tissue movement. The dynamic pipette aspiration setup has been miniaturized with regard to a future in-vivo application. The techniques were applied on 3 different porcine larynges 4 h and 1 d postmortem, in order to investigate the deterioration of the tissue over time and analyze correlation in elasticity values between vocal fold pairs. It was found that vocal fold pairs do have different absolute elasticity values but similar trends. This leads to the assumption that those trends are more important for phonation than having same absolute values

A Quasi-Static Quantitative Ultrasound Elastography Algorithm Using Optical Flow

Ultrasound elastography is a constantly developing imaging technique which is capable of displaying the elastic properties of tissue. The measured characteristics could help to refine physiological tissue models, but also indicate pathological changes. Therefore, elastography data give valuable insights into tissue properties. This paper presents an algorithm that measures the spatially resolved Young’s modulus of inhomogeneous gelatin phantoms using a CINE sequence of a quasi-static compression and a load cell measuring the compressing force. An optical flow algorithm evaluates the resulting images, the stresses and strains are computed, and, conclusively, the Young’s modulus and the Poisson’s ratio are calculated. The whole algorithm and its results are evaluated by a performance descriptor, which determines the subsequent calculation and gives the user a trustability index of the modulus estimation. The algorithm shows a good match between the mechanically measured modulus and the elastography result—more precisely, the relative error of the Young’s modulus estimation with a maximum error 35%. Therefore, this study presents a new algorithm that is capable of measuring the elastic properties of gelatin specimens in a quantitative way using only the image data. Further, the computation is monitored and evaluated by a performance descriptor, which measures the trustability of the results

Imaging the Vocal Folds: A Feasibility Study on Strain Imaging and Elastography of Porcine Vocal Folds

Vocal folds are an essential part of human voice production. The biomechanical properties are a good indicator for pathological changes. In particular, as an oscillation system, changes in the biomechanical properties have an impact on the vibration behavior. Subsequently, those changes could lead to voice-related disturbances. However, no existing examination combines biomechanical properties and spatial imaging. Therefore, we propose an image registration-based approach, using ultrasound in order to gain this information synchronously. We used a quasi-static load to compress the tissue and measured the displacement by image registration. The strain distribution was directly calculated from the displacement field, whereas the elastic properties were estimated by a finite element model. In order to show the feasibility and reliability of the algorithm, we tested it on gelatin phantoms. Further, by examining ex vivo porcine vocal folds, we were able to show the practicability of the approach. We displayed the strain distribution in the tissue and the elastic properties of the vocal folds. The results were superimposed on the corresponding ultrasound images. The findings are promising and show the feasibility of the suggested approach. Possible applications are in improved diagnosis of voice disorders, by measuring the biomechanical properties of the vocal folds with ultrasound. The transducer will be placed on the vocal folds of the anesthetized patient, and the elastic properties will be measured. Further, the understanding of the vocal folds’ biomechanics and the voice forming process could benefit from it

Electronic-photonic board as an integration platform for Tb/s multi-chip optical communication

Chip-on-board silicon photonics O-band wavelength-division multiplexing transceivers have been developed that will eventually enable high-throughput on-board optical communication for multi-socket on-board communication. This direct, any-to-any configuration yields low-latency, low-power optical communication among multiple compute nodes on the board. Silicon photonic transceiver chips are flip-chipped on a polymer waveguide containing an electro-optical circuit board using adiabatic coupling and then completed with driver and amplifier electronic chips. A transceiver assembly based on wire-bond technology verifies 50 Gb/s operation per channel, and the flip-chip version demonstrates the chip on-board assembly techniques for compact on-board transceivers

Stimmen von Schweizer Grossunternehmen zur digitalen Verwaltung der Schweiz

Die Digitalisierung bietet der öffentlichen Hand die Chance, durch innovative und moderne Interaktionsformen die bisherigen Dienstleistungen zu optimieren und neu zu gestalten. Es gilt dabei die Regulierungsvorschriften soweit wie möglich zu harmonisieren, Verwaltungsprozesse zu standardisieren und die entsprechenden technischen Systeme zu synchronisieren. Mit diesem Vorgehen können die Kosten bei Schweizer Unternehmen unmittelbar gesenkt, die Standortattraktivität der Schweiz mittelbar erhöht und gleichzeitig auch Effizienz und Effektivitätssteigerungen seitens der Verwaltung erzielt werden. Bei der digitalen Transformation der Verwaltung sind die Bedürfnisse der Unternehmen als Nutzende und Mitwirkende zu beachten, um eine benutzerfreundliche und zweckgemässe Umsetzung sicherzustellen. Dies ergab eine Umfrage bei acht grossen Schweizer Unternehmen (Migros, SBB, Novartis, Zurich Insurance Group, Nestlé, Swisscom, Swiss Life, IBM Schweiz), die in unterschiedlichen Branchen tätig und unterschiedlichen staatlichen Regulierungen (Lebensmittelhygiene, Berufsbildung/Lernende, Bauvorhaben, Rechnungslegung/Versicherungsaufsicht, Ein- und Ausfuhr von Waren, öffentliche Beschaffung, Mehrwertsteuer, ausländische Mitarbeitende) unterworfen sind. In Interviews gaben zwei der acht befragten Unternehmen an, dass die jeweiligen Verwaltungsdienstleistungen aktuell ausschliesslich digital erfolgen. Eine Mehrheit der befragten Unternehmen erachtet die Kommunikation mit der Verwaltung als einen wichtigen Standortvorteil. Bei der Realisierung von Schnittstellen zwischen Unternehmen und Verwaltung gilt es zu beachten, dass die vorherrschende Diversität durch Standardisierungen reduziert wird. Eine bundesweite und kantonsübergreifende Etablierung von offenen Schnittstellen zwischen Systemen der Unternehmen und jenen der Verwaltung kann zudem die Standortattraktivität der Schweiz erhöhen. In den Interviews gab die Mehrheit der Unternehmen an, dass die Standortattraktivität insgesamt in den letzten Jahren gleich geblieben ist. Digitale Interaktionen zwischen Unternehmen und Verwaltung sind zukunftsweisend und aus Sicht der befragten Unternehmen dringend auszubauen. Digitale Dienstleistungen schaffen gemäss diesen Unternehmen allerdings nur dann einen Mehrwert, wenn sie einen neuartigen und zeitsparenden Zugang zur Verwaltung ermöglichen und nicht nur die bestehenden analogen Prozesse übersetzen

Colonyzer: automated quantification of micro-organism growth characteristics on solid agar

<p>Abstract</p> <p>Background</p> <p>High-throughput screens comparing growth rates of arrays of distinct micro-organism cultures on solid agar are useful, rapid methods of quantifying genetic interactions. Growth rate is an informative phenotype which can be estimated by measuring cell densities at one or more times after inoculation. Precise estimates can be made by inoculating cultures onto agar and capturing cell density frequently by plate-scanning or photography, especially throughout the exponential growth phase, and summarising growth with a simple dynamic model (e.g. the logistic growth model). In order to parametrize such a model, a robust image analysis tool capable of capturing a wide range of cell densities from plate photographs is required.</p> <p>Results</p> <p>Colonyzer is a collection of image analysis algorithms for automatic quantification of the size, granularity, colour and location of micro-organism cultures grown on solid agar. Colonyzer is uniquely sensitive to extremely low cell densities photographed after dilute liquid culture inoculation (spotting) due to image segmentation using a mixed Gaussian model for plate-wide thresholding based on pixel intensity. Colonyzer is robust to slight experimental imperfections and corrects for lighting gradients which would otherwise introduce spatial bias to cell density estimates without the need for imaging dummy plates. Colonyzer is general enough to quantify cultures growing in any rectangular array format, either growing after pinning with a dense inoculum or growing with the irregular morphology characteristic of spotted cultures. Colonyzer was developed using the open source packages: Python, RPy and the Python Imaging Library and its source code and documentation are available on SourceForge under GNU General Public License. Colonyzer is adaptable to suit specific requirements: e.g. automatic detection of cultures at irregular locations on streaked plates for robotic picking, or decreasing analysis time by disabling components such as lighting correction or colour measures.</p> <p>Conclusion</p> <p>Colonyzer can automatically quantify culture growth from large batches of captured images of microbial cultures grown during genome-wide scans over the wide range of cell densities observable after highly dilute liquid spot inoculation, as well as after more concentrated pinning inoculation. Colonyzer is open-source, allowing users to assess it, adapt it to particular research requirements and to contribute to its development.</p

Language-Driven Engineering An Interdisciplinary Software Development Paradigm

We illustrate how purpose-specific, graphical modeling enables application experts with different levels of expertise to collaboratively design and then produce complex applications using their individual, purpose-specific modeling language. Our illustration includes seven graphical Integrated Modeling Environments (IMEs) that support full code generation, as well as four browser-based applications that were modeled and then fully automatically generated and produced using DIME, our most complex graphical IME. While the seven IMEs were chosen to illustrate the types of languages we support with our Language-Driven Engineering (LDE) approach, the four DIME products were chosen to give an impression of the power of our LDE-generated IMEs. In fact, Equinocs, Springer Nature's future editorial system for proceedings, is also being fully automatically generated and then deployed at their Dordrecht site using a deployment pipeline generated with Rig, one of the IMEs presented. Our technology is open source and the products presented are currently in use.Comment: 43 pages, 30 figure

Medical student ultrasound education, a WFUMB position paper, Part II. A consensus statement by ultrasound societies

Publisher Copyright: © 2020 Societatea Romana de Ultrasonografie in Medicina si Biologie. All rights reserved. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.Ultrasound is becoming a fundamental first-line diagnostic tool for most medical specialties and an innovative tool to teach anatomy, physiology and pathophysiology to undergraduate and graduate students. However, availability of structured training programs during medical school is lagging behind and many physicians still acquire all their ultrasound skills during postgraduate training. There is wide variation in medical student ultrasound education worldwide. Sharing successful educational strategies from early adopter medical schools and learning from leading education programs should advance the integration of ultrasound into the university medical school curricula. In this overview, we present current approaches and suggestions by ultrasound societies concerning medical student education throughout the world. Based on these examples, we formulate a consensus statement with suggestions on how to integrate ultrasound teaching into the preclinical and clinical medical curricula.publishersversionPeer reviewe