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Showing 81 to 90 of 90 (0.289 seconds)Spelling suggestions: "subject:"jacobi ""
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[pt] APLICAÇÕES DA EQUAÇÃO DO CALOR NA INDÚSTRIA DO PETRÓLEO / [en] APPLICATIONS OF HEAT EQUATION IN OIL INDUSTRYIAGO ARCAS DA FONSECA 17 December 2020 (has links)
[pt] Neste trabalho focamos sobre alguns modelos matemáticos na área do
petróleo, com o objetivo de propor um modelo inicial de simulador numérico
de reservatórios. Inicialmente apresentamos uma EDP do calor não-linear
com um termo fonte de calor constante, estudada para o domínio sendo uma
placa plana quadrada homogênea e heterogênea, onde aplicamos soluções
numéricas utilizando o método das diferenças finitas implícito. Abordamos
o problema de refinamento da malha no entorno dos poços utilizando o
método JFNK (Jacobian-Free Newton-Krylov), que aumenta a eficiência
computacional através de uma aproximação para a matriz Jacobiana. Por
fim resolvemos um sistema de EDPs não-lineares que representam o escoamento
bifásico de água e óleo, constituído por equações de transporte em
termos da pressão e da saturação. Fizemos simulações numéricas de alguns
casos conhecidos e os resultados mostraram uma boa qualidade no nosso
método. / [en] In this work we focus on the numerical approximation of some
mathematical models in the oil field. First, we present a non-linear heat
equation with a constant heat source term, studied for the domain of a
homogeneous and heterogeneous square domain, where we apply numerical
solutions using an implicit finite difference method. We approach the
problem of mesh refinement around the wells using the JFNK (Jacobian-
Free Newton-Krylov) method, which improves the computational efficiency
through an approximation to the Jacobian matrix. Finally, we solve a system
of non-linear EDPs that represent the two-phase flow of water and oil,
consisting of equations of transport in terms of pressure and saturation.
Numerical simulations for some known cases showed accurate approximation
of our method.
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Géométrie et arithmétique explicites des variétés abéliennes et applications à la cryptographieArène, Christophe 27 September 2011 (has links)
Les principaux objets étudiés dans cette thèse sont les équations décrivant le morphisme de groupe sur une variété abélienne, plongée dans un espace projectif, et leurs applications en cryptographie. Notons g sa dimension et k son corps de définition. Ce mémoire est composé de deux parties. La première porte sur l'étude des courbes d'Edwards, un modèle pour les courbes elliptiques possédant un sous-groupe de points k-rationnels cyclique d'ordre 4, connues en cryptographie pour l'efficacité de leur loi d'addition et la possibilité qu'elle soit définie pour toute paire de points k-rationnels (loi d'addition k-complète). Nous en donnons une interprétation géométrique et en déduisons des formules explicites pour le calcul du couplage de Tate réduit sur courbes d'Edwards tordues, dont l'efficacité rivalise avec les modèles elliptiques couramment utilisés. Cette partie se conclut par la génération, spécifique au calcul de couplages, de courbes d'Edwards dont les tailles correspondent aux standards cryptographiques actuellement en vigueur. Dans la seconde partie nous nous intéressons à la notion de complétude introduite ci-dessus. Cette propriété est cryptographiquement importante car elle permet d'éviter des attaques physiques, comme les attaques par canaux cachés, sur des cryptosystèmes basés sur les courbes elliptiques ou hyperelliptiques. Un précédent travail de Lange et Ruppert, basé sur la cohomologie des fibrés en droite, permet une approche théorique des lois d'addition. Nous présentons trois résultats importants : tout d'abord nous généralisons un résultat de Bosma et Lenstra en démontrant que le morphisme de groupe ne peut être décrit par strictement moins de g+1 lois d'addition sur la clôture algébrique de k. Ensuite nous démontrons que si le groupe de Galois absolu de k est infini, alors toute variété abélienne peut être plongée dans un espace projectif de manière à ce qu'il existe une loi d'addition k-complète. De plus, l'utilisation des variétés abéliennes nous limitant à celles de dimension un ou deux, nous démontrons qu'une telle loi existe pour leur plongement projectif usuel. Finalement, nous développons un algorithme, basé sur la théorie des fonctions thêta, calculant celle-ci dans P^15 sur la jacobienne d'une courbe de genre deux donnée par sa forme de Rosenhain. Il est désormais intégré au package AVIsogenies de Magma. / The main objects we study in this PhD thesis are the equations describing the group morphism on an abelian variety, embedded in a projective space, and their applications in cryptograhy. We denote by g its dimension and k its field of definition. This thesis is built in two parts. The first one is concerned by the study of Edwards curves, a model for elliptic curves having a cyclic subgroup of k-rational points of order 4, known in cryptography for the efficiency of their addition law and the fact that it can be defined for any couple of k-rational points (k-complete addition law). We give the corresponding geometric interpretation and deduce explicit formulae to calculate the reduced Tate pairing on twisted Edwards curves, whose efficiency compete with currently used elliptic models. The part ends with the generation, specific to pairing computation, of Edwards curves with today's cryptographic standard sizes. In the second part, we are interested in the notion of completeness introduced above. This property is cryptographically significant, indeed it permits to avoid physical attacks as side channel attacks, on elliptic -- or hyperelliptic -- curves cryptosystems. A preceeding work of Lange and Ruppert, based on cohomology of line bundles, brings a theoretic approach of addition laws. We present three important results: first of all we generalize a result of Bosma and Lenstra by proving that the group morphism can not be described by less than g+1 addition laws on the algebraic closure of k. Next, we prove that if the absolute Galois group of k is infinite, then any abelian variety can be projectively embedded together with a k-complete addition law. Moreover, a cryptographic use of abelian varieties restricting us to the dimension one and two cases, we prove that such a law exists for their classical projective embedding. Finally, we develop an algorithm, based on the theory of theta functions, computing this addition law in P^15 on the Jacobian of a genus two curve given in Rosenhain form. It is now included in AVIsogenies, a Magma package.
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3-D inversion of helicopter-borne electromagnetic dataScheunert, Mathias 19 January 2016 (has links) (PDF)
In an effort to improve the accuracy of common 1-D analysis for frequency domain helicopter-borne electromagnetic data at reasonable computing costs, a 3-D inversion approach is developed. The strategy is based on the prior localization of an entire helicopter-borne electromagnetic survey to parts which are actually affected by expected local 3-D anomalies and a separate inversion of those sections of the surveys (cut-&-paste strategy).
The discrete forward problem, adapted from the complete Helmholtz equation, is formulated in terms of the secondary electric field employing the finite difference method. The analytical primary field calculation incorporates an interpolation strategy that allows to effectively handle the enormous number of transmitters. For solving the inverse problem, a straightforward Gauss-Newton method and a Tikhonov-type regularization scheme are applied. In addition, different strategies for the restriction of the domain where the inverse problem is solved are used as an implicit regularization. The derived linear least squares problem is solved with Krylov-subspace methods, such as the LSQR algorithm, that are able to deal with the inherent ill-conditioning.
As the helicopter-borne electromagnetic problem is characterized by a unique transmitter-receiver relation, an explicit representation of the Jacobian matrix is used. It is shown that this ansatz is the crucial component of the 3-D HEM inversion. Furthermore, a tensor-based formulation is introduced that provides a fast update of the linear system of the forward problem and an effective handling of the sensitivity related algebraic quantities.
Based on a synthetic data set of a predefined model problem, different application examples are used to demonstrate the principal functionality of the presented algorithm. Finally, the algorithm is applied to a data set obtained from a real field survey in the Northern German Lowlands. / Die vorliegende Arbeit beschäftigt sich mit der 3-D Inversion von Hubschrauberelektromagnetikdaten im Frequenzbereich. Das vorgestellte Verfahren basiert auf einer vorhergehenden Eingrenzung des Messgebiets auf diejenigen Bereiche, in denen tatsächliche 3-D Strukturen im Untergrund vermutet werden. Die Resultate der 3-D Inversion dieser Teilbereiche können im Anschluss wieder in die Ergebnisse der Auswertung des komplementären Gesamtdatensatzes integriert werden, welche auf herkömmlichen 1-D Verfahren beruht (sog. Cut-&-Paste-Strategie).
Die Diskretisierung des Vorwärtsproblems, abgeleitet von einer Sekundärfeldformulierung der vollständigen Helmholtzgleichung, erfolgt mithilfe der Methode der Finiten Differenzen. Zur analytischen Berechnung der zugehörigen Primärfelder wird ein Interpolationsansatz verwendet, welcher den Umgang mit der enorm hohen Anzahl an Quellen ermöglicht. Die Lösung des inversen Problems basiert auf dem Gauß-Newton-Verfahren und dem Tichonow-Regularisierungsansatz. Als Mittel der zusätzlichen impliziten Regularisierung dient eine räumliche Eingrenzung des Gebiets, auf welchem das inverse Problem gelöst wird. Zur iterativen Lösung des zugrundeliegenden Kleinste-Quadrate-Problems werden Krylov-Unterraum-Verfahren, wie der LSQR Algorithmus, verwendet.
Aufgrund der charakteristischen Sender-Empfänger-Beziehung wird eine explizit berechnete Jakobimatrix genutzt. Ferner wird eine tensorbasierte Problemformulierung vorgestellt, welche die schnelle Assemblierung leitfähigkeitsabhängiger Systemmatrizen und die effektive Handhabung der zur Berechnung der Jakobimatrix notwendigen algebraischen Größen ermöglicht.
Die Funktionalität des beschriebenen Ansatzes wird anhand eines synthetischen Datensatzes zu einem definierten Testproblem überprüft. Abschließend werden Inversionsergebnisse zu Felddaten gezeigt, welche im Norddeutschen Tiefland erhoben worden.
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Abordagens do tipo livre de jacobiana na simulação do escoamento de fluidos compressíveis em meios porosos / Abordagens do tipo livre de jacobiana na simulação do escoamento de fluidos compressíveis em meios porosos / Study of a Jacobian-free approach in the simulation of compressible fluid flows in porous media using a derivative-free spectral method / Study of a Jacobian-free approach in the simulation of compressible fluid flows in porous media using a derivative-free spectral methodGisiane Santos Simão Ferreira 30 September 2014 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O desenvolvimento de software livre de Jacobiana para a resolução de problemas formulados por equações diferenciais parciais não-lineares é de interesse crescente para simular processos práticos de engenharia. Este trabalho utiliza o chamado algoritmo espectral livre de derivada para equações não-lineares na simulação de fluxos em meios porosos. O modelo aqui considerado é aquele empregado para descrever o deslocamento do fluido compressível miscível em meios porosos com fontes e sumidouros, onde a densidade da mistura de fluidos varia exponencialmente com a pressão. O algoritmo espectral utilizado é um método moderno para a solução de sistemas não-lineares de grande porte, o que não resolve sistemas lineares, nem usa qualquer informação explícita associados com a matriz Jacobiana, sendo uma abordagem livre de Jacobiana. Problemas bidimensionais são apresentados, juntamente com os resultados numéricos comparando o algoritmo espectral com um método de Newton inexato livre de Jacobiana. Os resultados deste trabalho mostram que este algoritmo espectral moderno é um método confiável e eficiente para a simulação de escoamentos compressíveis em meios porosos. / The development of Jacobian-free software for solving problems formulated by nonlinear partial differential equations is of increasing interest to simulate practical engineering processes. This work uses the so-called derivative-free spectral algorithm for nonlinear equations in the simulation of flows in porous media. The model considered here is the one employed to describe the displacement of miscible compressible fluid in porous media with point sources and sinks, where the density of the fluid mixture varies exponentially with the pressure. The spectral algorithm used is a modern method for solving large-scale nonlinear systems, which does not solve linear systems, nor use any explicit information associated with the Jacobin matrix, being a Jacobian-free approach. Two dimensional problems are presented, along with numerical results comparing the spectral algorithm to a well-developed Jacobian-free inexact Newton method. The results of this paper show that this modern spectral algorithm is a reliable and efficient method for simulation of compressible flows in porous media.
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Abordagens do tipo livre de jacobiana na simulação do escoamento de fluidos compressíveis em meios porosos / Abordagens do tipo livre de jacobiana na simulação do escoamento de fluidos compressíveis em meios porosos / Study of a Jacobian-free approach in the simulation of compressible fluid flows in porous media using a derivative-free spectral method / Study of a Jacobian-free approach in the simulation of compressible fluid flows in porous media using a derivative-free spectral methodGisiane Santos Simão Ferreira 30 September 2014 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O desenvolvimento de software livre de Jacobiana para a resolução de problemas formulados por equações diferenciais parciais não-lineares é de interesse crescente para simular processos práticos de engenharia. Este trabalho utiliza o chamado algoritmo espectral livre de derivada para equações não-lineares na simulação de fluxos em meios porosos. O modelo aqui considerado é aquele empregado para descrever o deslocamento do fluido compressível miscível em meios porosos com fontes e sumidouros, onde a densidade da mistura de fluidos varia exponencialmente com a pressão. O algoritmo espectral utilizado é um método moderno para a solução de sistemas não-lineares de grande porte, o que não resolve sistemas lineares, nem usa qualquer informação explícita associados com a matriz Jacobiana, sendo uma abordagem livre de Jacobiana. Problemas bidimensionais são apresentados, juntamente com os resultados numéricos comparando o algoritmo espectral com um método de Newton inexato livre de Jacobiana. Os resultados deste trabalho mostram que este algoritmo espectral moderno é um método confiável e eficiente para a simulação de escoamentos compressíveis em meios porosos. / The development of Jacobian-free software for solving problems formulated by nonlinear partial differential equations is of increasing interest to simulate practical engineering processes. This work uses the so-called derivative-free spectral algorithm for nonlinear equations in the simulation of flows in porous media. The model considered here is the one employed to describe the displacement of miscible compressible fluid in porous media with point sources and sinks, where the density of the fluid mixture varies exponentially with the pressure. The spectral algorithm used is a modern method for solving large-scale nonlinear systems, which does not solve linear systems, nor use any explicit information associated with the Jacobin matrix, being a Jacobian-free approach. Two dimensional problems are presented, along with numerical results comparing the spectral algorithm to a well-developed Jacobian-free inexact Newton method. The results of this paper show that this modern spectral algorithm is a reliable and efficient method for simulation of compressible flows in porous media.
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Grafické demo s inverzní kinematikou / Graphics Demo with Inverse KinematicsKárníková, Pavlína January 2010 (has links)
This work deals with the creation of a graphic demo with the use of inverse kinematics. It explains the motivations that led to the creation of the demo; it briefly mentions the history of the demo as well as the principles of animation. It describes in detail the fundamentals of inverse kinematics as well as the terminology needed for the understanding of inverse kinematics. It also includes some selected algorithms. The issue of inverse kinematics is further developed in the part of the work where the principles of skinning are being described. The principles of the collision detection are also mentioned here. The conclusion consists of a detailed explanation of some of the techniques used in graphic demo, such as the L-systems or procedural textures.
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3-D inversion of helicopter-borne electromagnetic dataScheunert, Mathias 27 November 2015 (has links)
In an effort to improve the accuracy of common 1-D analysis for frequency domain helicopter-borne electromagnetic data at reasonable computing costs, a 3-D inversion approach is developed. The strategy is based on the prior localization of an entire helicopter-borne electromagnetic survey to parts which are actually affected by expected local 3-D anomalies and a separate inversion of those sections of the surveys (cut-&-paste strategy).
The discrete forward problem, adapted from the complete Helmholtz equation, is formulated in terms of the secondary electric field employing the finite difference method. The analytical primary field calculation incorporates an interpolation strategy that allows to effectively handle the enormous number of transmitters. For solving the inverse problem, a straightforward Gauss-Newton method and a Tikhonov-type regularization scheme are applied. In addition, different strategies for the restriction of the domain where the inverse problem is solved are used as an implicit regularization. The derived linear least squares problem is solved with Krylov-subspace methods, such as the LSQR algorithm, that are able to deal with the inherent ill-conditioning.
As the helicopter-borne electromagnetic problem is characterized by a unique transmitter-receiver relation, an explicit representation of the Jacobian matrix is used. It is shown that this ansatz is the crucial component of the 3-D HEM inversion. Furthermore, a tensor-based formulation is introduced that provides a fast update of the linear system of the forward problem and an effective handling of the sensitivity related algebraic quantities.
Based on a synthetic data set of a predefined model problem, different application examples are used to demonstrate the principal functionality of the presented algorithm. Finally, the algorithm is applied to a data set obtained from a real field survey in the Northern German Lowlands. / Die vorliegende Arbeit beschäftigt sich mit der 3-D Inversion von Hubschrauberelektromagnetikdaten im Frequenzbereich. Das vorgestellte Verfahren basiert auf einer vorhergehenden Eingrenzung des Messgebiets auf diejenigen Bereiche, in denen tatsächliche 3-D Strukturen im Untergrund vermutet werden. Die Resultate der 3-D Inversion dieser Teilbereiche können im Anschluss wieder in die Ergebnisse der Auswertung des komplementären Gesamtdatensatzes integriert werden, welche auf herkömmlichen 1-D Verfahren beruht (sog. Cut-&-Paste-Strategie).
Die Diskretisierung des Vorwärtsproblems, abgeleitet von einer Sekundärfeldformulierung der vollständigen Helmholtzgleichung, erfolgt mithilfe der Methode der Finiten Differenzen. Zur analytischen Berechnung der zugehörigen Primärfelder wird ein Interpolationsansatz verwendet, welcher den Umgang mit der enorm hohen Anzahl an Quellen ermöglicht. Die Lösung des inversen Problems basiert auf dem Gauß-Newton-Verfahren und dem Tichonow-Regularisierungsansatz. Als Mittel der zusätzlichen impliziten Regularisierung dient eine räumliche Eingrenzung des Gebiets, auf welchem das inverse Problem gelöst wird. Zur iterativen Lösung des zugrundeliegenden Kleinste-Quadrate-Problems werden Krylov-Unterraum-Verfahren, wie der LSQR Algorithmus, verwendet.
Aufgrund der charakteristischen Sender-Empfänger-Beziehung wird eine explizit berechnete Jakobimatrix genutzt. Ferner wird eine tensorbasierte Problemformulierung vorgestellt, welche die schnelle Assemblierung leitfähigkeitsabhängiger Systemmatrizen und die effektive Handhabung der zur Berechnung der Jakobimatrix notwendigen algebraischen Größen ermöglicht.
Die Funktionalität des beschriebenen Ansatzes wird anhand eines synthetischen Datensatzes zu einem definierten Testproblem überprüft. Abschließend werden Inversionsergebnisse zu Felddaten gezeigt, welche im Norddeutschen Tiefland erhoben worden.
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Inverse Methods In Freeform OpticsLandwehr, Philipp, Cebatarauskas, Paulius, Rosztoczy, Csaba, Röpelinen, Santeri, Zanrosso, Maddalena 13 September 2023 (has links)
Traditional methods in optical design like ray tracing suffer from slow convergence and are not constructive, i.e., each minimal perturbation of input parameters might lead to “chaotic” changes in the output. However, so-called inverse methods can be helpful in designing optical systems of reflectors and lenses. The equations in R2 become ordinary differential equations, while in R3 the equations become partial differential equations. These equations are then used to transform source distributions into target distributions, where the distributions are arbitrary, though assumed to be positive and integrable. In this project, we derive the governing equations and solve them numerically, for the systems presented by our instructor Martijn Anthonissen [Anthonissen et al. 2021]. Additionally, we show how point sources can be derived as a special case of a interval source with di- rected source interval, i.e., with each point in the source interval there is also an associated unit direction vector which could be derived from a system of two interval sources in R2. This way, it is shown that connecting source distributions with target distributions can be classified into two instead of three categories.
The resulting description of point sources as a source along an interval with directed rays could potentially be extended to three dimensions, leading to interpretations of point sources as directed sources on convex or star-shaped sets.:1 Abstract 4
2 Notation And Conventions 4
3 Introduction 5
4 ECMI Modeling Week Challenges 5
4.1 Problem 1 - Parallel to Near-Field Target 5
4.1.1 Description 5
4.1.2 Deriving The Equations 5
4.2 Problem 2 - Parallel Source To Two Targets 8
4.3 Problem 3 - Point Source To Near-Field Target 9
4.3.1 Deriving The Equations 9
4.4 Problem 4 - Point Source To Two Targets 11
5 Validation - Ray tracing 13
5.1 Splines 13
5.1.1 Piece-Wise Affine Reflectors 13
5.1.2 Piece-Wise Cubic Reflectors 14
5.2 Error Estimates For Spline Reflectors 14
5.2.1 Lemma: A Priori Feasibility Of Starting Values For Near-Field Problems 15
5.2.2 Estimates for single reflector, near-field targets 16
5.3 Ray Tracing Errors - Illumination Errors 17
5.3.1 Definition: Axioms For Errors 18
5.3.2 Extrapolated Ray Tracing Error (ERTE) 18
5.3.3 Definition: Minimal Distance Ray Tracing Error (MIRTE) 19
5.3.4 Lemma: Continuity Of The Ray Traced Reflection Projection Of Smooth Reflectors 19
5.3.5 Theorem: Convergence Of The MIRTE 20
5.3.6 Convergence Of The ERTE 21
5.3.7 Application 21
6 Numerical Implementation 21
6.1 The DOPTICS Library 21
6.2 Pseudocode Of The Implementation 21
6.2.1 Solutions Of The Problems 22
6.2.2 Ray Tracing And Ray Tracing Error 22
6.3 ERTE Implementation 25
7 Results 26
7.1 Problem 1: Results 26
7.2 Problem 2: Results 26
7.3 Problem 3: Results 27
7.4 Problem 4: Results 27
8 Generalizations In Two Dimensions 29
8.1 Directed Densities 29
8.2 Generalized, Orthogonally Emitting Sources in R2 30
8.2.1 Point Light Sources As Orthogonally Emitting Sources 30
9 Conclusion and Future Research 32
10 Group Dynamic 32
References 32
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Design, Modeling, and Testing of a Force Feedback Haptic Device for Simulated Robot Interaction / Design, modellering, och test av en kraftåterkopplad haptisk pryl för simulerad robot interaktionLindström, Patrik January 2023 (has links)
Haptic feedback is a growing phenomenon that incorporates the sense of touch through tactile sensations such as vibrations, electrical signals, air pressure, and sound waves or through force feedback, which employs torques and/or forces to replicate the pressure and weight of a simulated object. Utilizing haptic technology establishes a communication bridge between the user and the technical component, enhancing the user's understanding of the technical component's surroundings. This thesis focuses on designing a force feedback haptic device with an impedance control strategy, enabling the imposition of dynamic behavior during simulated robot interactions. Impedance control is a commonly employed approach in haptic devices, utilizing a mass-spring-damper model to vary stiffness, damping, and inertia levels, thereby simulating realistic forces and torques in master-slave interactions. Initially, a haptic device resembling the shape of a Delta robot was designed using Solidworks, with size and weight distribution serving as the primary design considerations. Subsequently, the device was further represented using a generic robot description format, incorporating the design's joints and links. This representation was then paired with kinematic connections delineating the robot's motion and dynamic matrices to simulate the robot's movement. Alongside the integration of an impedance control strategy, simulations were conducted to emulate robot interactions. These simulations tested the system under various conditions, including scenarios with and without introduced torque disturbances. Including torque disturbances was intended to enhance the simulation's realism and assess the impact of impedance control parameter choices on the system's behavior. In summary, the research concludes how a closed-chain robot, the Delta robot, can be modeled as a haptic device with an impedance control strategy, offering valuable guidance for future research. / Haptisk återkoppling är ett växande fenomen som integreras i allt fler användningsområden. Genom att återskapa känslan av att röra vid eller interagera med föremål, antingen genom att simulera taktila sensationer som vibrationer, elektriska signaler, lufttryck och ljudvågor eller genom att återge kraftåterkoppling till användaren, kan användarens förståelse för tekniska komponenter och deras omgivning öka. Kraftåterkoppling möjliggör imitation av tryck och vikt hos simulaterade objekt, vilket förbättrar realismen i användarupplevelsen. Detta examensarbete har inriktat sig på att designa en haptisk pryl med kraftåterkoppling och en styrmekanism baserad på impedanskontroll. Genom att implementera impedanskontroll kan dynamiska beteenden inkorporeras i systemet genom varierande styrka, dämpning och tröghet. Dessa impedansparametrar möjliggör realistiska simuleringar av kraft och vridmoment i samband med virtuella robotinteraktioner. Först utformades en haptisk pryl som efterliknar formen av en Delta-robot med hjälp av CAD-programmet Solidworks. Här var storlek och viktfördelning primära överväganden i designprocessen. Därefter representerades enheten genom en generisk robotbeskrivning som inkluderade dess leder och länkar. Denna representation kopplades sedan ihop med kinematiska samband som reglerade enhetens rörelse. Tillsammans med integreringen av impedanskontrollstrategin genomfördes simuleringar som efterliknade robotinteraktioner. Dessa simuleringar omfattade olika scenarier, inklusive de med vridmomentsstörningar och de utan. Syftet med att inkludera vridmomentsstörningar var att öka realismen i simuleringen och utvärdera påverkan av valda parametrar för impedanskontrollen på systemets beteende. Sammanfattningsvis har detta arbete resulterat i utformningen av en haptisk pryl med kraftåterkoppling, som efterliknar en Delta-robot. Prylen har modellerats som en trädstruktur, med kinematiska samband som sammanfogar dess ändnoder. Det här arbetet har bidragit till kunskapen om hur realistiska haptiska interaktioner kan skapas och öppnat möjligheter för framtida forskning och utveckling inom detta område.
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Evaluation of Target Tracking Using Multiple Sensors and Non-Causal AlgorithmsVestin, Albin, Strandberg, Gustav January 2019 (has links)
Today, the main research field for the automotive industry is to find solutions for active safety. In order to perceive the surrounding environment, tracking nearby traffic objects plays an important role. Validation of the tracking performance is often done in staged traffic scenarios, where additional sensors, mounted on the vehicles, are used to obtain their true positions and velocities. The difficulty of evaluating the tracking performance complicates its development. An alternative approach studied in this thesis, is to record sequences and use non-causal algorithms, such as smoothing, instead of filtering to estimate the true target states. With this method, validation data for online, causal, target tracking algorithms can be obtained for all traffic scenarios without the need of extra sensors. We investigate how non-causal algorithms affects the target tracking performance using multiple sensors and dynamic models of different complexity. This is done to evaluate real-time methods against estimates obtained from non-causal filtering. Two different measurement units, a monocular camera and a LIDAR sensor, and two dynamic models are evaluated and compared using both causal and non-causal methods. The system is tested in two single object scenarios where ground truth is available and in three multi object scenarios without ground truth. Results from the two single object scenarios shows that tracking using only a monocular camera performs poorly since it is unable to measure the distance to objects. Here, a complementary LIDAR sensor improves the tracking performance significantly. The dynamic models are shown to have a small impact on the tracking performance, while the non-causal application gives a distinct improvement when tracking objects at large distances. Since the sequence can be reversed, the non-causal estimates are propagated from more certain states when the target is closer to the ego vehicle. For multiple object tracking, we find that correct associations between measurements and tracks are crucial for improving the tracking performance with non-causal algorithms.
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