Real-Time Numerical Simulation for Accurate Soft Tissues Modeling during Haptic Interaction

The simulation of fabrics physics and its interaction with the human body has been largely studied in recent years to provide realistic-looking garments and wears specifically in the entertainment business. When the purpose of the simulation is to obtain scientific measures and detailed mechanical properties of the interaction, the underlying physical models should be enhanced to obtain better simulation accuracy increasing the modeling complexity and relaxing the simulation timing constraints to properly solve the set of equations under analysis. However, in the specific field of haptic interaction, the desiderata are to have both physical consistency and high frame rate to display stable and coherent stimuli as feedback to the user requiring a tradeoff between accuracy and real-time interaction. This work introduces a haptic system for the evaluation of the fabric hand of specific garments either existing or yet to be produced in a virtual reality simulation. The modeling is based on the co-rotational Finite Element approach that allows for large displacements but the small deformation of the elements. The proposed system can be beneficial for the fabrics industry both in the design phase or in the presentation phase, where a virtual fabric portfolio can be shown to customers around the world. Results exhibit the feasibility of high-frequency real-time simulation for haptic interaction with virtual garments employing realistic mechanical properties of the fabric materials

Étude de la rotation d'objets dans une scène par analyse polarimétrique et radiométrique de fronts d'ondes

Dans ce papier, nous présentons une méthode originale de détermination de paramètres de rotation d'objets fondée sur l'analyse de l'état de polarisation des faisceaux réfléchis par la scène étudiée et une mise en correspondance spatio-temporelle par étude des histogrammes. Des résultats sur scènes réelles sont présentés

Development of an instrumented customizable total knee prosthesis for experimental tests.

Total knee arthroplasty (TKA) has revolutionized the life of millions of patients and it is the most efficient treatment in cases of osteoarthritis. The increase in life expectancy has lowered the average age of the patient, which requires a more enduring and performing prosthesis. To improve the design of implants and satisfying the patient's needs, a deep understanding of the knee Biomechanics is needed. To overcome the uncertainties of numerical models, recently instrumented knee prostheses are spreading. The aim of the thesis was to design and manifacture a new prototype of instrumented implant, able to measure kinetics and kinematics (in terms of medial and lateral forces and patellofemoral forces) of different interchangeable designs of prosthesis during experiments tests within a research laboratory, on robotic knee simulator. Unlike previous prototypes it was not aimed for industrial applications, but purely focusing on research. After a careful study of the literature, and a preliminary analytic study, the device was created modifying the structure of a commercial prosthesis and transforming it in a load cell. For monitoring the kinematics of the femoral component a three-layers, piezoelettric position sensor was manifactured using a Velostat foil. This sensor has responded well to pilot test. Once completed, such device can be used to validate existing numerical models of the knee and of TKA and create new ones, more accurate.It can lead to refinement of surgical techniques, to enhancement of prosthetic designs and, once validated, and if properly modified, it can be used also intraoperatively

Recalage/Fusion d'images multimodales à l'aide de graphes d'ordres supérieurs

The main objective of this thesis is the exploration of higher order Markov Random Fields for image registration, specifically to encode the knowledge of global transformations, like rigid transformations, into the graph structure. Our main framework applies to 2D-2D or 3D-3D registration and use a hierarchical grid-based Markov Random Field model where the hidden variables are the displacements vectors of the control points of the grid.We first present the construction of a graph that allows to perform linear registration, which means here that we can perform affine registration, rigid registration, or similarity registration with the same graph while changing only one potential. Our framework is thus modular regarding the sought transformation and the metric used. Inference is performed with Dual Decomposition, which allows to handle the higher order hyperedges and which ensures the global optimum of the function is reached if we have an agreement among the slaves. A similar structure is also used to perform 2D-3D registration.Second, we fuse our former graph with another structure able to perform deformable registration. The resulting graph is more complex and another optimisation algorithm, called Alternating Direction Method of Multipliers is needed to obtain a better solution within reasonable time. It is an improvement of Dual Decomposition which speeds up the convergence. This framework is able to solve simultaneously both linear and deformable registration which allows to remove a potential bias created by the standard approach of consecutive registrations.L’objectif principal de cette thèse est l’exploration du recalage d’images à l’aide de champs aléatoires de Markov d’ordres supérieurs, et plus spécifiquement d’intégrer la connaissance de transformations globales comme une transformation rigide, dans la structure du graphe. Notre cadre principal s’applique au recalage 2D-2D ou 3D-3D et utilise une approche hiérarchique d’un modèle de champ de Markov dont le graphe est une grille régulière. Les variables cachées sont les vecteurs de déplacements des points de contrôle de la grille.Tout d’abord nous expliciterons la construction du graphe qui permet de recaler des images en cherchant entre elles une transformation affine, rigide, ou une similarité, tout en ne changeant qu’un potentiel sur l’ensemble du graphe, ce qui assure une flexibilité lors du recalage. Le choix de la métrique est également laissée à l’utilisateur et ne modifie pas le fonctionnement de notre algorithme. Nous utilisons l’algorithme d’optimisation de décomposition duale qui permet de gérer les hyper-arêtes du graphe et qui garantit l’obtention du minimum exact de la fonction pourvu que l’on ait un accord entre les esclaves. Un graphe similaire est utilisé pour réaliser du recalage 2D-3D.Ensuite, nous fusionnons le graphe précédent avec un autre graphe construit pour réaliser le recalage déformable. Le graphe résultant de cette fusion est plus complexe et, afin d’obtenir un résultat en un temps raisonnable, nous utilisons une méthode d’optimisation appelée ADMM (Alternating Direction Method of Multipliers) qui a pour but d’accélérer la convergence de la décomposition duale. Nous pouvons alors résoudre simultanément recalage affine et déformable, ce qui nous débarrasse du biais potentiel issu de l’approche classique qui consiste à recaler affinement puis de manière déformable

Shear-promoted drug encapsulation into red blood cells: a CFD model and μ-PIV analysis

The present work focuses on the main parameters that influence shear-promoted encapsulation of drugs into erythrocytes. A CFD model was built to investigate the fluid dynamics of a suspension of particles flowing in a commercial micro channel. Micro Particle Image Velocimetry (μ-PIV) allowed to take into account for the real properties of the red blood cell (RBC), thus having a deeper understanding of the process. Coupling these results with an analytical diffusion model, suitable working conditions were defined for different values of haematocrit

A numerical study on the aerodynamic forces and the wake stability of flapping flight at low Reynolds number

Mención Internacional en el título de doctorThe unsteady aerodynamics that govern flapping flight at low Reynolds number are not yet properly understood. This means that air vehicles that use flapping wings to generate both thrust and lift do not show the desired performance. Many works on the aerodynamic forces of flapping airfoils can be found in the literature, but still our capability to predict these forces is limited. Most of these studies focus on flapping airfoils, assuming infinite aspect ratio wings and Two Dimensional (2D) flow. To what extent the 2D assumption is valid is uncertain. Furthermore, a very few studies address the effect that Three Dimensional (3D) flow structures originated by flow instabilities in infinite aspect ratio wings have on the aerodynamic forces. In this work we present Direct Numerical Simulations of heaving and pitching airfoils at low Reynolds number where the airfoil motion is prescribed by sinusoidal laws. The parameter space of this problem is huge, so only the mean pitch angle and the phase shift between the heaving and pitching motions are modified. We generate a database of 18 cases and analyze the integrated values of thrust and lift of each case. Also, a reference case is selected to perform a detailed analysis of the forces and decompose the total aerodynamic force in contributions from body motion, vorticity within the flow and surface vorticity. This analysis is extended to a subset of cases from the database in order to study the influence of the motion parameters on the aerodynamic forces. After that, we proceed to estimate the aerodynamic forces by existing models from the literature and, based on observations made through this work, we propose a modification to increase the accuracy of the predicted forces. Finally, we compute the total aerodynamic force as the combination of the contribution from body motion and vorticity within the flow, neglecting surface vorticity effects. This proposed model shows remarkable results for the prediction of thrust and good results for the lift. After analyzing the aerodynamic forces of the 2D cases, we proceed to study the three-dimensionality of the flow of part of the database. First, we present a stability analysis of four of the cases from the database. Each case is studied by Floquet stability analysis. The four cases considered display different wake structures resulting in different mean aerodynamic forces. Two cases produce thrust and lift, one case only thrust (with symmetric heaving and pitching) and the remaining case mainly lift (with the highest mean pitch angle). In addition, the latter case displays a period doubling phenomenon, and it is found to be linearly unstable for long wavelengths, with an instability mode that resembles that of mode A found in the wake of cylinders. Other cases, although being linearly stable, present a convective instability at smaller wavelengths. Finally, the unstable case has been studied with a fully 3D DNS to evaluate the effect of the three-dimensionality on the forces. The resulting flow structure is consistent with the linear stability analysis in the near wake. Further downstream nonlinearities lead to a fully 3D wake. Despite this, the aerodynamic forces on the 3D wing are very similar to those obtained in the 2D simulation.La aerodinámica no estacionaria que gobierna el vuelo de alas batientes a bajo número de Reynolds todavía no se entiende correctamente. Esto significa que los vehículos aéreos que usan alas batientes para generar empuje y sustentación no consiguen el rendimiento deseado. En la literatura, se pueden encontrar muchos trabajos sobre fuerzas aerodinámicas en perfiles batientes, pero aún así nuestra capacidad para predecir estas fuerzas es limitada. La mayoría de estos estudios se centran en perfiles, asumiendo un ala de relación de aspecto infinito y flujo bidimensional (2D). El rango de validez de la hipótesis 2D es es incierto. Además, muy pocos estudios abordan el efecto que tienen las estructuras tridimensionales (3D) originadas por inestabilidades del flujo en alas de relación de aspecto infinito sobre las fuerzas aerodinámicas. En este trabajo presentamos simulaciones numéricas directas de perfiles batientes a bajo número de Reynolds donde el movimiento del perfil aerodinámico es prescrito por leyes sinusoidales. El espacio de paramétrico de este problema es enorme, por lo que sólo se modifican el ángulo de ataque medio y la diferencia de fase entre los movimientos vertical y de cabeceo. Generamos una base de datos de 18 casos y analizamos los valores medios de empuje y sustentación para cada caso. También se selecciona un caso de referencia para realizar un análisis detallado de las fuerzas y, además, descomponer la fuerza aerodinámica total en las contribuciones de movimiento del cuerpo, de vorticidad contenida en el flujo y de vorticidad superficial. Este análisis se extiende a un subconjunto de casos de la base de datos con el fin de estudiar la influencia de los parámetros de movimiento sobre las fuerzas aerodinámicas. Posteriormente, se procede a estimar las fuerzas aerodinámicas por modelos de orden reducido presentes en la literatura y, a basándones en observaciones realizadas en este trabajo, se propone una modificación para aumentar la precisión de las fuerzas obtenidas. Finalmente, se calcula la fuerza aerodinámica total como la suma de la contribución de movimiento del cuerpo y de vorticidad contenida en el flujo, sin considerar efectos de la vorticidad superficial. Este modelo propuesto muestra resultados notables para la predicción del empuje y buenos resultados para la sustentación.Programa Oficial de Doctorado en Mecánica de FluidosPresidente: Ramón Fernández Feria.- Secretario: Javier Rodríguez Rodríguez.- Vocal: Jan Wissin

Robot Manipulators

Robot manipulators are developing more in the direction of industrial robots than of human workers. Recently, the applications of robot manipulators are spreading their focus, for example Da Vinci as a medical robot, ASIMO as a humanoid robot and so on. There are many research topics within the field of robot manipulators, e.g. motion planning, cooperation with a human, and fusion with external sensors like vision, haptic and force, etc. Moreover, these include both technical problems in the industry and theoretical problems in the academic fields. This book is a collection of papers presenting the latest research issues from around the world

Turbulent structure in environmental flows: effects of stratification and rotation

Several series of experiments in stratified and in rotating/stratified decaying flows after a grid is used to stir the two layer stable fluid brine and fresh water set up. We measure by comparing the gained potential energy with the available kinetic energy AKE, the relative efficiency of mixing. The experiments in stratified rotating flows with grid driven turbulence were both periodic (quasi stationary) and non-monotonic (decaying) forcing. This thesis compares experimental, numerical and field observations on the structure and Topology of the Stratified Rotating Flows as well as their decay, the horizontal spectra changes appreciable with slopes from 1.1 to 5, but vorticity and local circulation, and also the initial topology and forcing of the flow. A detailed study of the vorticity decay and vortex and energy structure has been performed, the new results show that neither stratified nor rotating flows exhibit pure 2D structures. The work parameterizes the role of the Richardson number and the Rossby number, both in the experiments and in the ocean visualizations is very important. The conditions of vortex decay show the effects of the internal waves in the decay turbulent conditions both for stratified and rotating flows. The parameter space (Re,Ri,Ro) has been used to interpret many previously disconnected explanations of the 2D-3D turbulent behaviour. The comparison of numerical simulations with experiments has allowed implementing new theoretical aspects of the interaction between waves and vortices finding the surprising and very interesting result that these interactions depend on the level of enstrophy. This also leads to new ways of using multifractal analysis ad intermittency in ocean environmental observations. A large collection of SAR images obtained from three European coastal areas were used for routine satellite analysis by SAR and other sensors, which seem very important to build seasonal databases of the dynamic conditions of ocean mixing. The topology of the basic flow is very important and in particular the topology of the vortices and their decay which depends on ambient factors such as wave activity, wind and currents. We find more realistic estimates of the spatial/temporal non-homogeneities (and intermittency obtained as spatial correlations of the turbulent dissipation); these values are used to parameterize the sea surface turbulence, as well as a laboratory experiments at a variety of scales. Using multi-fractal geometry as well, we can establish now a theoretical pattern for the turbulence behaviour that is reflected in the different descriptors. Vorticity evolution is smoother and different than that of scalar or tracer density. The correlation between the local Ri and the fractal dimension detected from energy or entropy is good. Using multi-fractal geometry we can also establish certain regions of higher local activity used to establish the geometry of the turbulence mixing that needs to be studied in detail when interpreting the complex balance between the direct 3D Kolmogorov type cascade and the Inverse 2D Kraichnan type cascade

A Panorama on Multiscale Geometric Representations, Intertwining Spatial, Directional and Frequency Selectivity

The richness of natural images makes the quest for optimal representations in image processing and computer vision challenging. The latter observation has not prevented the design of image representations, which trade off between efficiency and complexity, while achieving accurate rendering of smooth regions as well as reproducing faithful contours and textures. The most recent ones, proposed in the past decade, share an hybrid heritage highlighting the multiscale and oriented nature of edges and patterns in images. This paper presents a panorama of the aforementioned literature on decompositions in multiscale, multi-orientation bases or dictionaries. They typically exhibit redundancy to improve sparsity in the transformed domain and sometimes its invariance with respect to simple geometric deformations (translation, rotation). Oriented multiscale dictionaries extend traditional wavelet processing and may offer rotation invariance. Highly redundant dictionaries require specific algorithms to simplify the search for an efficient (sparse) representation. We also discuss the extension of multiscale geometric decompositions to non-Euclidean domains such as the sphere or arbitrary meshed surfaces. The etymology of panorama suggests an overview, based on a choice of partially overlapping "pictures". We hope that this paper will contribute to the appreciation and apprehension of a stream of current research directions in image understanding.Comment: 65 pages, 33 figures, 303 reference

Integración de Proyección de Franjas y Correlación digital de imagines 2D para la medida de deformaciones y desplazamientos

[ES] En esta tesis se presenta un novedoso sistema que permite medir los desplazamientos en las direcciones X-, Y- y Z- ocurridos en la superficie de un objeto sometido a deformación. El método seguido se basa en combinar las técnicas 2D-DIC y FP. Éste sistema propuesto obtiene dichos resultados a partir de la adquisición de tan sólo una imagen por cada etapa de la deformación del objeto, lo que permite la adquisición de datos en tiempo real. Además, permite una completa y sencilla calibración de los parámetros necesarios para la corrección de los desplazamientos medidos en el plano. Para ilustrar el potencial del sistema propuesto, se ha realizado una serie de experimentos estáticos y dinámicos. Los resultados se han comparado con los obtenidos empleando un sistema Correlación Digital de Imágenes 3D comercial, manifestando un nivel de concordancia muy alto con diferencias menores del 5%.[EN]This thesis presents a novel system to measure displacements in X-, Y-and Z-directions occurring on the surface of an object under deformation. The employed method is based on combining 2D-DIC and FP techniques. This proposed system obtains those results from the acquisition of only one image per each stage of the deformation of the object, enabling real time data acquisition. In addition it allows a complete and simple calibration procedure of the required parameters for the correction of the measured in the plane displacements. To illustrate the potential of the proposed system it has been performed a series of static and dynamic experiments. The results were compared with those obtained using a Digital Mapping 3D images commercial system, showing a high level of concordance with differences lower to 5%.Tesis Univ. Jaén. Departamento de Ingeniería Mecánica y Minera, leída el 25 de marzo de 201