A 3D environment for surgical planning and simulation

The use of Computed Tomography (CT) images and their three-dimensional (3D) reconstruction has spread in the last decade for implantology and surgery. A common use of acquired CT datasets is to be handled by dedicated software that provide a work context to accomplish preoperative planning upon. These software are able to exploit image processing techniques and computer graphics to provide fundamental information needed to work in safety, in order to minimize the surgeon possible error during the surgical operation. However, most of them carry on lacks and flaws, that compromise the precision and additional safety that their use should provide. The research accomplished during my PhD career has concerned the development of an optimized software for surgical preoperative planning. With this purpose, the state of the art has been analyzed, and main deficiencies have been identified. Then, in order to produce practical solutions, those lacks and defects have been contextualized in a medical field in particular: it has been opted for oral implantology, due to the available support of a pool of implantologists. It has emerged that most software systems for oral implantology, that are based on a multi-view approach, often accompanied with a 3D rendered model, are affected by the following problems: unreliability of measurements computed upon misleading views (panoramic one), as well as a not optimized use of the 3D environment, significant planning errors implied by the software work context (incorrect cross-sectional planes), and absence of automatic recognition of fundamental anatomies (as the mandibular canal). Thus, it has been defined a fully 3D approach, and a planning software system in particular, where image processing and computer graphic techniques have been used to create a smooth and user-friendly completely-3D environment to work upon for oral implant planning and simulation. Interpolation of the axial slices is used to produce a continuous radiographic volume and to get an isotropic voxel, in order to achieve a correct work context. Freedom of choosing, arbitrarily, during the planning phase, the best cross-sectional plane for achieving correct measurements is obtained through interpolation and texture generation. Correct orientation of the planned implants is also easily computed, by exploiting a radiological mask with radio-opaque markers, worn by the patient during the CT scan, and reconstructing the cross-sectional images along the preferred directions. The mandibular canal is automatically recognised through an adaptive surface-extracting statistical-segmentation based algorithm developed on purpose. Then, aiming at completing the overall approach, interfacing between the software and an anthropomorphic robot, in order to being able to transfer the planning on a surgical guide, has been achieved through proper coordinates change and exploiting a physical reference frame in the radiological stent. Finally, every software feature has been evaluated and validated, statistically or clinically, and it has resulted that the precision achieved outperforms the one in literature

Deterministic Sampling for Nonlinear Dynamic State Estimation

The goal of this work is improving existing and suggesting novel filtering algorithms for nonlinear dynamic state estimation. Nonlinearity is considered in two ways: First, propagation is improved by proposing novel methods for approximating continuous probability distributions by discrete distributions defined on the same continuous domain. Second, nonlinear underlying domains are considered by proposing novel filters that inherently take the underlying geometry of these domains into account

Trajectory generation for autonomous unmanned aircraft using inverse dynamics

The problem addressed in this research is the in-flight generation of trajectories for autonomous unmanned aircraft, which requires a method of generating pseudo-optimal trajectories in near-real-time, on-board the aircraft, and without external intervention. The focus of this research is the enhancement of a particular inverse dynamics direct method that is a candidate solution to the problem. This research introduces the following contributions to the method. A quaternion-based inverse dynamics model is introduced that represents all orientations without singularities, permits smooth interpolation of orientations, and generates more accurate controls than the previous Euler-angle model. Algorithmic modifications are introduced that: overcome singularities arising from parameterization and discretization; combine analytic and finite difference expressions to improve the accuracy of controls and constraints; remove roll ill-conditioning when the normal load factor is near zero, and extend the method to handle negative-g orientations. It is also shown in this research that quadratic interpolation improves the accuracy and speed of constraint evaluation. The method is known to lead to a multimodal constrained nonlinear optimization problem. The performance of the method with four nonlinear programming algorithms was investigated: a differential evolution algorithm was found to be capable of over 99% successful convergence, to generate solutions with better optimality than the quasi- Newton and derivative-free algorithms against which it was tested, but to be up to an order of magnitude slower than those algorithms. The effects of the degree and form of polynomial airspeed parameterization on optimization performance were investigated, and results were obtained that quantify the achievable optimality as a function of the parameterization degree. Overall, it was found that the method is a potentially viable method of on-board near- real-time trajectory generation for unmanned aircraft but for this potential to be realized in practice further improvements in computational speed are desirable. Candidate optimization strategies are identified for future research.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Enhancing Mesh Deformation Realism: Dynamic Mesostructure Detailing and Procedural Microstructure Synthesis

Propomos uma solução para gerar dados de mapas de relevo dinâmicos para simular deformações em superfícies macias, com foco na pele humana. A solução incorpora a simulação de rugas ao nível mesoestrutural e utiliza texturas procedurais para adicionar detalhes de microestrutura estáticos. Oferece flexibilidade além da pele humana, permitindo a geração de padrões que imitam deformações em outros materiais macios, como couro, durante a animação. As soluções existentes para simular rugas e pistas de deformação frequentemente dependem de hardware especializado, que é dispendioso e de difícil acesso. Além disso, depender exclusivamente de dados capturados limita a direção artística e dificulta a adaptação a mudanças. Em contraste, a solução proposta permite a síntese dinâmica de texturas que se adaptam às deformações subjacentes da malha de forma fisicamente plausível. Vários métodos foram explorados para sintetizar rugas diretamente na geometria, mas sofrem de limitações como auto-interseções e maiores requisitos de armazenamento. A intervenção manual de artistas na criação de mapas de rugas e mapas de tensão permite controle, mas pode ser limitada em deformações complexas ou onde maior realismo seja necessário. O nosso trabalho destaca o potencial dos métodos procedimentais para aprimorar a geração de padrões de deformação dinâmica, incluindo rugas, com maior controle criativo e sem depender de dados capturados. A incorporação de padrões procedimentais estáticos melhora o realismo, e a abordagem pode ser estendida além da pele para outros materiais macios.We propose a solution for generating dynamic heightmap data to simulate deformations for soft surfaces, with a focus on human skin. The solution incorporates mesostructure-level wrinkles and utilizes procedural textures to add static microstructure details. It offers flexibility beyond human skin, enabling the generation of patterns mimicking deformations in other soft materials, such as leater, during animation. Existing solutions for simulating wrinkles and deformation cues often rely on specialized hardware, which is costly and not easily accessible. Moreover, relying solely on captured data limits artistic direction and hinders adaptability to changes. In contrast, our proposed solution provides dynamic texture synthesis that adapts to underlying mesh deformations. Various methods have been explored to synthesize wrinkles directly to the geometry, but they suffer from limitations such as self-intersections and increased storage requirements. Manual intervention by artists using wrinkle maps and tension maps provides control but may be limited to the physics-based simulations. Our research presents the potential of procedural methods to enhance the generation of dynamic deformation patterns, including wrinkles, with greater creative control and without reliance on captured data. Incorporating static procedural patterns improves realism, and the approach can be extended to other soft-materials beyond skin

Light Scattering by Non-Spherical Particles

Nicht-sphärische Teilchen sind in der Natur sowie in verfahrenstechnischen Anwendungen sehr häufig anzutreffen. Insbesondere die Detektion von Eiskristallen während des Fluges durch Verkehrsflugzeuge ist ein Problem, dass in den vergangenen Jahren vermehrt Aufmerksamkeit erhalten hat. Während das Problem der Streuung einer ebenen elektromagnetischen Welle durch ein homogenes und isotropes sphärisches Teilchen, wie z.B. einen Regentropfen als vollständig gelöst anzusehen ist, ist dies bei nicht-sphärischen Partikeln nicht der Fall. Hier existiert nach wie vor ein Fokus der Forschung und Entwicklung sowohl auf theoretischer, numerischer, als auch experimenteller Seite, aufgrund einer Vielzahl an unterschiedlichen Schwierigkeiten. Diese Arbeit beschreibt verschiedene numerische und semianalytische Verfahren, die auf das Streuproblem angewandt werden können und dabei die gesamte Reichweite des maßgeblichen Mie-Größenparameters abdecken. Diese Methoden werden auf die Kalibration und Interpretation der Messergebnisse des PHIPS-Messinstruments angewandt, welches in einer HALO Kampagne zur Charakterisierung von atmosphärischen Eiskristallen erprobt wurde. Die Berechnungsmethoden im Einzelnen beinhalten zwei Derivate der geometrischen Optik, anwendbar auf beliebige Partikel-Geometrien mit homogenem, als auch inhomogenem Brechungsindex, das numerisch exakte Verfahren der Finiten Integration der Maxwell-Gleichungen, sowie die in der Lichtstreuung und Quantenmechanik häufig verwendete Transitionsoperator-Methode. Diese Berechnungsmethoden werden auf eine Reihe von Beispiel- Geometrien angewandt und der Einfluss von Polarisation und gemittelter Partikel-Orientierung werden untersucht. Zusätzlich wurde ein Verfahren implementiert, dass das Strahlprofil eines Laserstrahls auf die gestreute Lichtintensität berücksichtigt, welches beispielsweise in der Anwendung bei Time-Shift Messungen eine zentrale Rolle spielt. Die Grenzen der Anwendbarkeit der verschiedenen Berechnungsmethoden werden in der Arbeit erläutert. Des Weiteren werden mehrere moderne Messverfahren auf ihre Anwendbarkeit im Hinblick auf nicht-sphärische Teilchen hin überprüft. Dies beinhaltet unter anderem das Time-Shift Messverfahren, sowie interferometrische bildgebende Verfahren. Die Analyse der Anwendbarkeit der verschiedenen Messmethoden ist im experimentellen Abschnitt der Arbeit dokumentiert. Messungen der Streulicht-Phasenfunktionen von natürlichen Eiskristallen wurden ebenfalls durchgeführt und die spezifischen Vorbereitungen für die Untersuchungen von Eiskristallen in einem optischen Experiment werden in dieser Arbeit ebenfalls erläutert. Als gemeinsame Problematik konnte bei vielen Verfahren der limitierte Dynamikbereich der verwendeten Detektoren identifiziert werden. Ein abschließender wichtiger Aspekt in dieser Arbeit ist die Produktion und Aufbewahrung von Eiskristallen mit möglichst natürlichen optischen Eigenschaften in einer Laborumgebung. Hierfür wurde eine kompakte Wolkenkammer entwickelt, die die geforderten Eigenschaften an Produktionsmenge und Qualität von Eiskristallen erfüllt. Auslegung, Konstruktion und Betrieb des Apparates werden im letzten Kapitel der Dissertation detailliert wiedergegeben

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