De nombreux scanners laser permettent d'obtenir la surface 3D a partir d'un objet. Néanmoins, la surface reconstruite est souvent lisse, ce qui est du au débruitage interne du scanner et aux décalages entre les scans. Cette these utilise des scans haute precision et choisit de ne pas perdre ni alterer les echantillons initiaux au cours du traitement afin de les visualiser. C'est en effet la seule façon de decouvrir les imperfections (trous, decalages de scans). De plus, comme les donnees haute precision capturent meme le plus leger detail, tout debruitage ou sous-echantillonnage peut amener a perdre ces details.La these s'attache a prouver que l'on peut trianguler le nuage de point initial en ne perdant presque aucun echantillon. Le probleme de la visualisation exacte sur des donnees de plus de 35 millions de points et de 300 scans differents est ainsi resolu. Deux problemes majeurs sont traites: le premier est l'orientation du nuage de point brut complet et la creation d'un maillage. Le second est la correction des petits decalages entre les scans qui peuvent creer un tres fort aliasing et compromettre la visualisation de la surface. Le second developpement de la these est une decomposition des nuages de points en hautes/basses frequences. Ainsi, des methodes classiques pour l'analyse d'image, l'arbre des ensembles de niveau et la representation MSER, sont etendues aux maillages, ce qui donne une methode intrinseque de segmentation de maillages. Une analyse mathematiques d'operateurs differentiels discrets, proposes dans la litterature et operant sur des nuages de points est realisee. En considerant les developpements asymptotiques de ces operateurs sur une surface reguliere, ces operateurs peuvent etre classifies. Cette analyse amene au developpement d'un operateur discret consistant avec Ie mouvement par courbure moyenne (l'equation de la chaleur intrinseque) definissant ainsi un espace-echelle numerique simple et remarquablement robuste. Cet espace-echelle permet de resoudre de maniere unifiee tous les problemes mentionnes auparavant (orientation et triangulation du nuage de points, fusion de scans, segmentation de maillages) qui sont ordinairement traites avec des techniques distinctes. / Many laser devices acquire directly 3D objects and reconstruct their surface. Nevertheless, the final reconstructed surface is usually smoothed out as a result of the scanner internal de-noising process and the offsets between different scans. This thesis, working on results from high precision scans, adopts the somewhat extreme conservative position, not to loose or alter any raw sample throughout the whole processing pipeline, and to attempt to visualize them. Indeed, it is the only way to discover all surface imperfections (holes, offsets). Furthermore, since high precision data can capture the slightest surface variation, any smoothing and any sub-sampling can incur in the loss of textural detail.The thesis attempts to prove that one can triangulate the raw point cloud with almost no sample loss. It solves the exact visualization problem on large data sets of up to 35 million points made of 300 different scan sweeps and more. Two major problems are addressed. The first one is the orientation of the complete raw point set, an the building of a high precision mesh. The second one is the correction of the tiny scan misalignments which can cause strong high frequency aliasing and hamper completely a direct visualization.The second development of the thesis is a general low-high frequency decomposition algorithm for any point cloud. Thus classic image analysis tools, the level set tree and the MSER representations, are extended to meshes, yielding an intrinsic mesh segmentation method.The underlying mathematical development focuses on an analysis of a half dozen discrete differential operators acting on raw point clouds which have been proposed in the literature. By considering the asymptotic behavior of these operators on a smooth surface, a classification by their underlying curvature operators is obtained.This analysis leads to the development of a discrete operator consistent with the mean curvature motion (the intrinsic heat equation) defining a remarkably simple and robust numerical scale space. By this scale space all of the above mentioned problems (point set orientation, raw point set triangulation, scan merging, segmentation), usually addressed by separated techniques, are solved in a unified framework.

Im Jahr 1991 wurde erstmals die Interferenz von Atomen experimentell nachgewiesen. Seitdem wird dieses Phänomen in vielen Bereichen der Grundlagenforschung angewendet, unter anderem zur Bestimmung von Naturkonstanten mit bisher unerreichter Genauigkeit oder für Tests des Äquivalenzprinzips. Grundsätzlich können auch geophysikalische Vermessungen des Schwerefeldes der Erde von dieser neuen Technik profitieren, allerdings waren Atominterferometrie-Experimente aufgrund ihrer Komplexität bisher nur in Laboren möglich. Erst kürzlich wurde mit der Entwicklung mobiler Atominterferometer begonnen, die nun die hochpräzise Messung von Rotationen, Gravitationsgradienten sowie der absoluten Schwerebeschleunigung außerhalb von Laboren ermöglichen. Im Rahmen dieser Arbeit wurde ein absolutes Gravimeter entwickelt, konstruiert und getestet. Es basiert auf Rb87-Atomen, die in einer Vakuumumgebung gefangen, gekühlt und senkrecht entgegen der Erdanziehung beschleunigt werden. Während des anschließenden freien Falls werden die atomaren Ensembles durch drei Raman Lichtpulse aufgespalten und rekombiniert. Die lokale Schwerebeschleunigung kann aus den resultierenden Interferenzmustern bestimmt werden, die abhängig von der Bewegung der Atome in einem Gravitationspotential sind. Wir haben den Wert der lokalen Schwerebeschleunigung, g, mit einer Auflösung von 1 : 10^10 bei einer Integrationszeit von 12 Stunden vermessen. Dies entspricht 2,2 * 10^-7 m/s^2/Sqrt(Hz). Mit dieser Genauigkeit konnten bereits zeitliche Veränderungen des lokalen Schwerefeldes registriert werden, hervorgerufen durch eine Vielzahl an Effekten wie Erd- und Ozeangezeiten oder atmosphärischen Variationen. In einem Vergleich unter ähnlichen Messbedingungen konnte unser Instrument die lokale Schwerebeschleunigung mit einer um fast eine Größenordnung höheren Genauigkeit bestimmen als ein herkömmliches Gravimeter. / Since 1991, matter wave interferometry has been used in many laboratories for a variety of fundamental physics experiments, e.g. measurement of the fine-structure and gravity constants or equivalence principle tests. This new technique is also ideally suited for high-accuracy geophysical gravity measurements. However, due to the complexity of these experiments they were so far confined to laboratory environments. Only in recent years efforts have been undertaken to develop mobile atom interferometers. These new sensors now open up the possibility to perform on-site high-precision measurements of rotations, gravity gradients as well as absolute accelerations. This work reports on the design, construction and first tests of an absolute gravimeter. It is based on interfering ensembles of laser cooled Rb87 atoms in a one meter high atomic fountain configuration. Local gravity is measured by applying three Raman light pulses while the atoms are in free fall, thereby splitting and recombining the atomic wave packets. The resulting interference fringes are sensitive to the movement of the atoms within a gravitational potential. We have measured the value of local gravity g at a resolution of one part in 10^10 at an integration time of 12 hours, or 2.2 * 10^-7 m/s^2/Sqrt(Hz). This was high enough to be sensitive to a number of time varying gravity effects like tides, ocean loading or changes in gravity caused by air pressure. In a comparison under similar measurement conditions, the instrument has surpassed the performance of conventional mobile gravimeters by almost one order of magnitude.

Atom Interferometrie ist eine sehr genaue und sensitive Methode mit einer Vielzahl von Anwendungsmöglichkeiten, zu der auch die Messung der Erdbeschleunigung zählt. Während die meisten Atom Interferometer aus großen, ortsfesten Aufbauten bestehen, werden auf diesem Gebiet häufig mobile Messgeräte benötigt. Das Gravimetric Atom Interferometer (GAIN) Projekt wurde ins Leben gerufen, um dieser zusätzlichen Anforderung bei bestmöglicher Messgenauigkeit gerecht zu werden. Es soll eine Alternative zu anderen modernsten Gravimetertypen geschaffen werden, die wichtige funktionale Eigenschaften wie eine hohe Auflösung und absolute Genauigkeit in einem Gerät vereint. Der GAIN Sensor verwendet lasergekühlte Rb87 Atome in einer 1 m hohen Fontäne. Mit Hilfe von stimulierten Raman Übergängen wird ein beschleunigungssensitives Interferometer realisiert. In dieser Arbeit wurde der Sensor mit Blick auf mobile und driftfreie Langzeitmessungen weiterentwickelt. Dafür wurden einzelne Subsysteme des Laseraufbaus auf die daraus resultierenden Anforderungen hin angepasst oder neu entwickelt. Mit derselben Zielstellung wurden weiterhin systematische Effekte in dem Messaufbau untersucht und Maßnahmen für ihre Reduzierung realisiert. Der Aufbau wurde transportiert und in relevanten Umgebungen getestet. Dabei konnte gezeigt werden, dass die Leistungsfäigkeit dieses Aufbaus mit denen der wichtigsten und modernsten Gravimeter konkurieren kann, sie teilweise übertrifft und dass dieser Sensor zur präzisen Kalibrierung der relativen Gravimeter verwendet werden kann. In den Messungen wurde eine Sensitivität von 138 nm/s^2/Sqrt(Hz) sowie eine Langzeitstabilität von 5 x 10^−11 g über 10^5 s erreicht. / Atom interferometry offers a very precise and sensitive measurement tool for various areas of application whereof one is the registration of the gravity acceleration. While the vast majority of atom interferometers include large and stationary setups, this field very often implies the additional request for a mobile apparatus. The Gravimetric Atom Interferometer (GAIN) project has been started to meet this requirement and to provide best possible accuracy at the same time. It aims to realize an alternative to other types of gravimeters and to combine important qualities such as high sensitivity and absolute accuracy in one instrument. The GAIN sensor is based on laser-cooled Rb87 atoms in a 1 m atomic fountain. Stimulated Raman transitions form a Mach-Zehnder type interferometer which is sensitive to accelerations. In this work it has been advanced to meet all requirements for mobile and drift-free long-term operation. Therefore, selected parts of the laser system have been improved or redeveloped. A second focus has been on systematic effects for the same objective. They have been analyzed and measures for their suppression have been undertaken. The apparatus has been transported, tested in relevant environments, and compared to the most important state-of-the-art gravimeter types where a competitive performance has been achieved. It is demonstrated, that the gravity signal of this sensor allows for a precise calibration of the relative gravimeter types. During the measurements a best sensitivity of 138 nm/s^2/Sqrt(Hz) and a stability of 5 x 10^−11 g after 10^5 s has been reached.

On-machine inspection (OMI) via on-machine probing (OMP) is a technology that has the potential to provide a step change in the manufacturing of high precision products. Bringing product inspection closer to the machining process is very attractive proposition for many manufacturers who demand ever better quality, process control and efficiency from their manufacturing systems. However, there is a shortness of understanding, experience, and knowledge with regards to efficiently implementing OMI on industrially-based multi-axis machine tools. Coupled with the risks associated to this disruptive technology, these are major obstacles preventing OMI from being confidently adopted in many high precision manufacturing environments. The research pursued in this thesis investigates the concept of enabling high precision machine tools as measurement devices and focuses upon the question of: “How can traceable on-machine inspection be enabled and sustained in an industrial environment?” As highlighted by the literature and state-of-the-art review, much research and development focuses on the technology surrounding particular aspects of machine tool metrology and measurement whether this is theory, hardware, software, or simulation. Little research has been performed in terms of confirming the viability of industrial OMI and the systematic and holistic application of existing and new technology to enable optimal intervention. This EngD research has contributed towards the use of industrial machine tools as traceable measurement systems. Through the test cases performed, the novel concepts proposed, and solutions tested, a series of fundamental questions have been addressed. Thus, providing new knowledge and use to future researchers, engineers, consultants and manufacturing professionals.

The object of this master´s thesis was levelling and weight measurement of the Tetčice polygon through which passes the fault of the Boskovice furrow. This is the 10th period of levelling and the second period of gravimetric measurement. The theoretical part describes the geological structure of the site, technology of high-precision levelling and technology of gravimetric measurement. The first part of the practical part deals with my own levelling measurement, the calculation of the resulting cambers and heights, consequential comparasion of the results with previous periods and, especially, with evaluation of the vertical movement tendecies. The second part of the practical part deals with my own gravimetric measurement, the calculation of the complete Bouguer gravity anomaly, creation map of complete Bouguer gravity anomaly and as well as evaluation of gravimetric measurement in relation to the results of the previous periods.

The new generation of giant ground-based telescopes will see their first light this decade. These state-of-the-art facilities will significantly surpass the resolving power of modern space-based observatories such as the James Webb telescope, thanks to their enormous aperture size and adaptive optics (AO) facilities. Without AO, atmospheric turbulence would degrade the image quality of these enormous telescopes to that of a 50 cm amateur one. These extremely large telescopes (ELTs) will further benefit from a particular branch of AO called multi-conjugate adaptive optics (MCAO), which provides an extremely high resolving power over a much wider field of view as compared to classical AO systems. The design and fabrication of such systems, as well as their optimal use for science operation, pose a great challenge as they are an order of magnitude more complicated than current AO systems. To face such a challenge, the combined knowledge of MCAO system design and fabrication, working in tandem with scientific insights into new astronomy science cases, is an extremely valuable and essential pairing. This thesis is an effort to not only contribute to the design and fabrication of ELT MCAO facilities, but also provide guidance on the optimal method to utilize these giant telescopes to achieve unprecedented astrometric measurements. On the instrumentation side, in partnership with the National Research Council of Canada's - Herzberg Astronomy and Astrophysics Institute as well as W.M. Keck Observatory in Hawaii, I was involved in the design and fabrication of a cutting edge new wavefront sensor, which is the eye of an AO system. I performed opto-mechanical design and verification studies for components of the Keck infrared pyramid wavefront sensor (IR-PWFS) as well as the Keck Planet Imager and characterizer (KPIC) instrument, which have both been commissioned and are in science operation. Furthermore, I designed the alignment plan and participated in the modification and alignment operation of a few components on the Keck II adaptive optics bench on the summit of Mauna Kea. To pave the way for the design verification of future MCAO systems for ELTs, I proposed a new method for an old challenge in the path of AO system design and verification: a flexible method for precise intensity pattern injection into laboratory AO benches. AO benches are the backbone of instrument design and modeling. One of the challenges especially important for the future generation of MCAO systems for ELTs is the verification of the effect of shadowed regions on the primary mirror. During my PhD, I successfully demonstrated the feasibility of a new proposed method to accurately model the telescope pupil. This work was done in partnership with the Laboratoire d'Astrophysique de Marseille (LAM) in France. The method I developed at LAM will be implemented in the AO Lab at NRC Herzberg Astronomy and Astrophysics. As an observational astronomer, I focused on developing methods for making optimal astrometric measurements with MCAO-enabled telescopes. The expected unparalleled astrometric precision of ELTs comes with many unprecedented challenges that if left unresolved, would jeopardize the success of these facilities as they would not be able to reach their science goals. I used observations with the only available MCAO system in science operation, the Gemini MCAO system on the 8-meter Gemini South telescope in Chile, to develop and verify a pipeline specifically designed for very high-precision astrometric studies with MCAO-fed imagers. I successfully used the pipeline to provide the precise on-sky differential distortion of the Gemini South telescope and its MCAO facilities by looking deep into the core of globular cluster NGC~6723. Using this pipeline, I produced high quality proper motions with an uncertainty floor of $\sim 45$\,$\mu$as~yr$^{-1}$ as well as measured the proper motion dispersion profile of NGC~6723 from a radius of $\sim 10$ arcseconds out to $\sim 1$\,arcminute, based on $\sim 12000$ stars. I also produced a high-quality optical-near-infrared color magnitude diagram which clearly shows the extreme horizontal branch and main-sequence knee of this cluster. / Graduate

Robot arms require actuators that are powerful, precise and safe. The safety concern is amplified when these robots work closely with people in collaborative applications. This thesis investigates the design and implementation of hybrid pneumatic-electric actuators (HPEA) for use in robot arms, particularly those intended for collaborative applications. The initial focus was on improving the control of an existing single HPEA-driven rotary joint. The torque is produced by four pneumatic cylinders connected in parallel with a small DC motor. The DC motor is directly connected to the output shaft. A cascaded control system is designed that consists of an outer position control loop and an inner pressure control loop. The pressure controller is based on a novel inverse valve model. High precision position tracking control is achieved due to the combination of the model-based pressure controller, model-based position controller, adaptive friction compensator and offline payload estimator. Experiments are performed with the actuator prototype rotating a link and payload with a rotational inertia equivalent to a linear actuator moving a 573 kg mass. Averaged over five tests, a root-mean-square error of 0.024° and a steady-state error (SSE) of 0.0045° are achieved for a fast multi-cycloidal trajectory. This SSE is almost ten times smaller than the best value reported for previous HPEAs. An offline payload estimation algorithm is used to improve the control system’s robustness. The superior safety of the HPEA is shown by modeling and simulating a constrained robot-head impact, and comparing the result with equivalent electric and pneumatic actuators. This research produced two journal papers. Since HPEAs are redundant actuators that combine the large force, low bandwidth characteristics of pneumatic actuators with the large bandwidth, small force characteristics of electric actuators, the effect of using optimization-based input allocation for HPEAs was studied. The goal was to improve the HPEA’s performance by distributing the required input (force or torque) between the redundant actuators in accordance with each actuator’s advantages and limitations. Three novel model-predictive control (MPC) approaches are designed to solve the position tracking and input allocation problems using convex optimization. The approaches are simulated on a HPEA-driven system and compared to a conventional linear controller without active input allocation. The first MPC approach uses a model that includes the dynamics of the payload and pneumatics; and performs the motion control using a single loop. The latter methods simplify the MPC law by separating the position and pressure controllers. Although the linear controller is the most computationally efficient, it is inferior to the MPC-based controllers in position tracking and force allocation performance. The third MPC-based controller design demonstrated the best position tracking with root mean square errors of 46%, 20%, and 55% smaller than the other three approaches. It also demonstrated sufficient speed for real-time operation. This research produced one journal paper. The research continued with the design and implementation of a two degree-of-freedom HPEA-driven arm. A HPEA-driven “elbow” joint is designed and added to the existing “shoulder” joint. The force from a single pneumatic cylinder is converted into torque using a 4-bar linkage. To eliminate backlash and keep the weight of the arm low, a 2nd smaller DC motor is directly connected to the joint. The kinematic and kinetic models of the new arm, as well as the geometry of the new elbow joint are studied. The resulting joint design is implemented, tested and controlled. This joint could achieve a SSE of 0.0045° in spite of its nonlinear joint geometry. The arm is experimentally tested for simultaneous tracking control of the two joints, and for end-effector position tracking in Cartesian space. The end-effector is able to follow a circular trajectory in pneumatic mode with position errors below 0.005 m. / Thesis / Doctor of Philosophy (PhD) / Robots that work with, or near, humans require greater safety considerations than other robots. A significant concern is collisions between the robot and humans that may happen when sensors or software fails. An actuator for robots that combines the inherent safety of pneumatic actuators with the accuracy of electric actuators, termed a “hybrid pneumatic electric actuator” (HPEA), is investigated. The design, instrumentation, modelling, and control of HPEAs are studied theoretically and experimentally. The proposed actuator could achieve high position control accuracy in a variety of experiments, with steady state error of less than 0.0045 degrees. Simulated impacts with a human head also showed that a HPEA-driven robot arm can achieve a 52% lower impact force, compared to an arm driven by conventional electric actuators. The HPEA design and control experiments are performed on a single HPEA-driven joint and extended to an arm consisting of two HPEA-driven revolute joints.

No description available.

Gitter QCD strebt nach höherer Präzision. Hier untersuchen wir zwei kritische Punkte, die zur Genauigkeit von Gitter-Ergebnissen beitragen. Im ersten Teil kalibrieren wir Gitterabstände von QCD Simulationen mit 2 + 1 Arten (flavor) dynamischer Quarks. Dabei nutzen wir neue Messungen und eine mehrere Modelle für den chiralen- und Kontinuumslimes, um die Ergebnisse der 2017 durchgeführten Studie [1] zu verbessern. Der zweite Teil befasst sich mit Simulationsalgorithmen. Wir testen einen Algorithmus, der eine schnellere Lösung der Dirac-Gleichung verspricht. Wir analysieren die Anwendung des FETI-Algorithmus (Finite Element Tear and Interconnect) im Zusammenhang mit Gitter-QCD-Simulationen und vergleichen ihn mit anderen modernen Lösungsverfahren aus der Klasse der Domänendekompositionslösern. Wir untersuchen verschiedene Präkonditionierer und ihre Auswirkungen auf die Konvergenz der Lösung. / Lattice QCD simulations strive for higher precision. Here, we study two critical points in the generation of high precision lattice results. In the first part, we calibrate the lattice spacings of QCD simulation with 2 + 1 flavors of dynamical fermions. We incorporate new measurements and use additional models for the chiral and continuum extrapolations to refine the result obtained in 2017 [1]. The second part focuses on simulation algorithms. We test an algorithm which promises faster solution of the Dirac equation. We analyze the application of the Finite Element Tear and Interconnect (FETI) algorithm in the context of lattice QCD simulations and compare it to other state-of-the-art domain decomposition solvers. We examine various preconditioners and their effects on the convergence of the solution.

No description available.