Robots moving about in complex environments must be capable of determining and performing difficult motion sequences to accomplish tasks. As the tasks become more complicated, robots with greater dexterity are required. An increase in the number of degrees of freedom and a desire for autonomy in uncertain environments with real-time requirements leaves much room for improvement in the current popular robot motion planning algorithms. In this thesis, state of the art robot motion planning techniques are surveyed. A solution to the general movers problem in the context of motion planning for robots is presented. The proposed robot motion planner solves the general movers problem using a sample-based tree planner combined with an incremental simulator. The robot motion planner is demonstrated both in simulation and the real world. Experiments are conducted and the results analyzed. Based on the results, methods for tuning the robot motion planner to improve the performance are proposed.

This paper proposes the position control of an articulated manipulator of two degrees of freedom driven by induction motors with a controller in the current loop. The work includes the mechanical modeling of the handler that will be developed from the direct and inverse kinematics and position control of induction motors operating system and uncoupled allocated in the manipulator. Thus, we developed two strategies for control of manipulators with two degrees of freedom, one using the scheme for field-oriented vector control and other means of indirect sliding mode control (Sliding-Mode Control - SMC). These control strategies are applied to current loop of induction motors that drive the manipulator. The parameters of the position controller of manipulator are taken into account in calculating the controller parameters of the current control loop, in order to obtain satisfactory results in the positioning the degrees of freedom. In addition, we performed a comparative study between the indirect field-oriented vector control and sliding mode control applied to the current loop. The advantage of the SMC compared to the indirect field-oriented vector control due to the first had in its control law, developed in this thesis, the use of position degree of freedom manipulator applied directly in the control law, while the second acted only as a disturbed rejection controller for the position loop. The Proportional-Integral (PI) was used in the position and speed loops for both current control algorithms to provide a standard for comparison between. For the purpose of implementing the control system individually for each engine and motors coupled to the manipulator used a digital signal processor. / O presente trabalho propÃe o controle de posiÃÃo de um manipulador articulado de dois graus de liberdade acionado a partir de motores de induÃÃo trifÃsicos com um controlador na malha de corrente. O trabalho contempla a modelagem mecÃnica do manipulador que serà desenvolvida a partir das cinemÃticas direta e inversa e o controle de posiÃÃo dos motores de induÃÃo atuando desacoplados do sistema e alocados no manipulador. Deste modo, foram desenvolvidas duas estratÃgias de controle de manipuladores com dois graus de liberdade, uma utilizando o esquema por controle vetorial de campo orientado indireto e outra atravÃs de controle por modos deslizantes (Sliding Mode Control â SMC). Estas estratÃgias de controle sÃo aplicadas a malha de corrente dos motores de induÃÃo que acionam o manipulador. Os parÃmetros do controlador de posiÃÃo dos manipuladores sÃo levados em consideraÃÃo no cÃlculo dos parÃmetros do controlador da malha de controle de corrente, de modo a se obter resultados satisfatÃrios no posicionamento dos graus de liberdade. AlÃm disso, foi realizado um estudo comparativo entre o controle vetorial de campo orientado indireto e o controle de modos deslizantes aplicado na malha de corrente. A vantagem do SMC em relaÃÃo ao controle vetorial de campo orientado indireto deveu-se a que o primeiro possuÃa em sua lei de controle desenvolvida nesta tese a utilizaÃÃo direta da posiÃÃo do grau de liberdade do manipulador, enquanto que o segundo atuava somente como um controlador com rejeiÃÃo ao distÃrbio. O controlador Proporcional-Integral (PI) foi utilizado nas malhas de posiÃÃo e velocidade de modo a fornecer um padrÃo de comparaÃÃo confiÃvel entre os controladores de corrente. Com a finalidade de implementar o sistema de controle de cada motor individualmente e dos motores acoplados ao manipulador utilizou-se um processador digital de sinais.

Made available in DSpace on 2014-07-29T15:08:24Z (GMT). No. of bitstreams: 1 Dissertacao - Fernando Goncalves Abadia.pdf: 2172647 bytes, checksum: 521c16d1c14b335efd25247e9a66c082 (MD5) Previous issue date: 2010-04-19 / Rehabilitation robotics involves the development of active devices for various processes in the health field. In the rehabilitation case, it replace the physical assistance by a robotic device, under the supervision of the therapist. According to some authors, there is much evidence that repetitive movements can help in the rehabilitation of stroke patients. Therefore, there is feasibility of building a low cost robotic manipulator of an anthropomorphic arm with few degrees of freedom in the rehabilitation of patients in early brain injury phase (muscle hypotony phase). The objective of the study outlined here is to determine, through simulation, the appropriate kinematic of an anthropomorphic robotic manipulator that best approximate the functional movements to be relearned by stroke patients. The kinemetry was the method used to measure the characteristics of these movements. The data acquisition was performed from three subjects who performed the movements of combing hair, drinking from cup, bring it to his mouth and waving, greeting movement. These data were compared with the direct and inverse kinematics of the simulated manipulator in MatLab environment. The results showed that, despite the limitations of movements, the simulated manipulator is feasible for rehabilitation of patients who are in the initial phase of stroke, with a low cost of implementation. / A reabilitação robótica é uma ciência que permite o desenvolvimento de dispositivos ativos para vários processos no campo da saúde. No caso da reabilitação, substitui a assistência física por um dispositivo robótico, sob a supervisão do terapeuta. Segundo alguns autores, há muitas evidências de que os movimentos repetitivos podem ajudar na reabilitação de pacientes vítimas de choques traumáticos ou de acidente vascular encefálico - AVE. Nesta perspectiva há viabilidade de se construir um manipulador robótico de um braço antropomórfico com poucos graus de liberdade na reabilitação dos pacientes na fase inicial do AVE (fase de hipotonia muscular) visando baixos custos. Neste aspecto, o objetivo do presente projeto é determinar, por meio de simulação, as apropriadas modelagens da cinemática de um manipulador robótico de um braço antropomórfico que melhor se aproximem dos movimentos funcionais a fim de serem reaprendidos pelos pacientes. A cinemetria foi o método utilizado para avaliar as características cinemáticas destes movimentos, a partir da coleta de dados realizada com uma amostra constituída por três sujeitos, que realizaram os movimentos de pentear os cabelos, pegar um copo e levá-lo à boca e acenar cumprimentando. Estes dados foram comparados à cinemática direta e inversa do manipulador simulado em ambiente MatLab. Os resultados mostraram que, apesar das limitações dos movimentos, o manipulador simulado é viável para reabilitação de pacientes que se encontram na fase inicial do AVE, apresentando um baixo custo de implementação.

This thesis focuses on the problem of determining appropriate skeletal configurations for which a virtual animated character moves to desired positions as smoothly, rapidly, and as accurately as possible. During the last decades, several methods and techniques, sophisticated or heuristic, have been presented to produce smooth and natural solutions to the Inverse Kinematics (IK) problem. However, many of the currently available methods suffer from high computational cost and production of unrealistic poses. In this study, a novel heuristic method, called Forward And Backward Reaching Inverse Kinematics (FABRIK), is proposed, which returnsvisually natural poses in real-time, equally comparable with highly sophisticated approaches. It is capable of supporting constraints for most of the known joint types and it can be extended to solve problems with multiple end effectors, multiple targets and closed loops. FABRIK wascompared against the most popular IK approaches and evaluated in terms of its robustness and performance limitations. This thesis also includes a robust methodology for marker prediction under multiple marker occlusion for extended time periods, in order to drive real-time centre of rotation (CoR) estimations. Inferred information from neighbouring markers has been utilised, assuming that the inter-marker distances remain constant over time. This is the firsttime where the useful information about the missing markers positions which are partially visible to a single camera is deployed. Experiments demonstrate that the proposed methodology can effectively track the occluded markers with high accuracy, even if the occlusion persists for extended periods of time, recovering in real-time good estimates of the true joint positions. In addition, the predicted positions of the joints were further improved by employing FABRIK to relocate their positions and ensure a fixed bone length over time. Our methodology is tested against some of the most popular methods for marker prediction and the results confirm that our approach outperforms these methods in estimating both marker and CoR positions. Finally, an efficient model for real-time hand tracking and reconstruction that requires a minimumnumber of available markers, one on each finger, is presented. The proposed hand modelis highly constrained with joint rotational and orientational constraints, restricting the fingers and palm movements to an appropriate feasible set. FABRIK is then incorporated to estimate the remaining joint positions and to fit them to the hand model. Physiological constraints, such as inertia, abduction, flexion etc, are also incorporated to correct the final hand posture. A mesh deformation algorithm is then applied to visualise the movements of the underlying hand skeleton for comparison with the true hand poses. The mathematical framework used for describing and implementing the techniques discussed within this thesis is Conformal GeometricAlgebra (CGA).

This master thesis is focused on Modular Self-Reconfigurable Robotic Systems. Their description is made at first and then possibilities of their use are listed. The next chapter concerns Molecubes modular system. The design of similar system where the construction of the individual modules is described follows. The transformations of coordinated systems in the individual modules are described and the calculation of forward kinematics and simulation of inverse kinematics is made at the end of the thesis.

The aim of the thesis is to propose and make a robot, which is made of identical modules. These modules are able to connect or disconnect themselves and thanks to this feature new structures of robot can be achieved. This problem is solved by the design proposal of a module, which is capable to rotate in two axis and has connection connectors for other modules. Communication is carried out by Wi-fi connection to the computer and angles required for reconfiguration are calculated by inverse kinematics in Matlab program. On these modules the reconfiguration test was succesfully demonstrated.

Understanding how diffuse molecular clouds at large scales (~10 pc) assemble mass into dense, star-forming cores at small scales (~ 0.1 pc) is crucial to building a holistic theory of star formation. While recent observations suggest that filaments play an important role in the mass assembly of dense cores, detailed gas kinematics studies are still lacking. My dissertation presents three innovative techniques that enable us to study star-forming filaments' complex gas kinematics in unprecedented detail: multi-component spectral fit, multi-dimensional filament identification, and membership assignment of velocity-coherent structures. Through these techniques, I analyzed star-forming filaments in the Perseus Molecular Cloud and unveiled unexpectedly complex velocity structures at scales where filaments are well resolved, to as low as the 0.01 pc scale. Moreover, the correlations I discovered between the various filament properties further suggest a scenario in which thermally supercritical filaments grow continuously via accretion from their surroundings while simultaneously forming cores through fragmentation along their lengths. / Graduate / 2022-01-08

This dissertation work is a study of the growth kinematics, synthesis strategies and intrinsic properties of InSb nanowires (NWs). The highlights of this work include a study of the effect of the growth parameters on the composition and crystallinity of NWs. A change in the temperature ramp-up rate as the substrate was heated to reach the NW growth temperature resulted in NWs that were either crystalline or amorphous. The as-grown NWs were found to have very different optical and electrical properties. The growth mechanism for crystalline NWs is the standard vapor-liquid-solid growth mechanism. This work proposes two possible growth mechanisms for amorphous NWs. The amorphous InSb NWs were found to be very sensitive to laser radiation and to heat treatment. Raman spectroscopy measurements on these NWs showed that intense laser light induced localized crystallization, most likely due to radiation induced annealing of defects in the region hit by the laser beam. Electron transport measurements revealed non-linear current-voltage characteristics that could not be explained by a Schottky diode behavior. Analysis of the experimental data showed that electrical conduction in this material is governed by space charge limited current (SCLC) in the high bias-field region and by Ohm's law in the low bias region. Temperature dependent conductivity measurements on these NWs revealed that conduction follows Mott variable range hopping mechanism at low temperatures and near neighbor hopping mechanism at high temperature. Low-temperature annealing of the amorphous NWs in an inert environment was found to induce a phase transformation of the NWs, causing their crystallinity to be enhanced. This thesis also proposes a new and low-cost strategy to grow p-type InSb NWs on InSb films grown on glass substrate. The high quality polycrystalline InSb film was used as the host on which the NWs were grown. The NWs with an average diameter of 150 nm and length of 20 μm were shown to have hole concentration of about 1017 cm-3 and mobility of about 1000 cm2V-1s-1. This thesis also proposes a strategy for the fabrication of metal-semiconductor nanocomposites. InSb NWs grown by electrochemical deposition were decorated with nanometer sized Au and Ag nanoparticles to form the nanocomposite.

Wir behandeln einige Spezialfälle von Beziehungen zwischen Eich- und Gravitationstheorien. Wir setzen den Schwerpunkt auf Baumlevelstreuamplituden in Einstein-(Skalar-)-Chromo-Dynamik, welche Streuungen zwischen Gluonen, massiven fundamentalen Quarks (Skalaren) und Gravitonen beschreibt. Wir untersuchen den endlichen Anteil von reiner Gluonenstreuung mit zwei kollinearen Gluonen. Basierend auf einem Vorschlag von S. Stieberger und T. Taylor, stehen diese in Beziehung zu Steuamplituden in Einstein-Yang-Mills Theorie, in welchen die kollinearen Gluonen durch ein Graviton ersetzt werden. Wir führen einen Beweis dieser Beziehungen unter der Ausnutzung des Cachazo-He-Yuan Formalismus durch. Parallel dazu werden wir einen Einblick in mysteriöse Wechselwirkunen dieser Beziehungen mit Eichinvarianzverletzungen des kollinearen Gluon Grenzwertes von Yang-Mills Streuampliuden geben. Danach behandeln wir eine andere Art von linearen Beziehungen zwischen Streuamplituden in Yang-Mills Theorie und Einstein-Yang-Mills Theorie, welche ebenfalls von S. Stieberger und T. Taylor vorgeschlagen wurden und direkt einzelne Gluonen mit einzelnen Gravitonen verbinden. Wir beweisen die Universalität dieser Beziehungen, in Anwesenheit von fundamental geladenen und massiven Fermionen und Skalaren. Schliesslich formulieren wir eine neue Zweifachkopiebeziehung zwischen klassisch effektiven Wirkungen. Die effektive Wirkung eines Systems von farblich geladenen, massiven und klassischen Weltlinien, welche über Yang-Mills wechselwirken, wird mit einem System von dilatonisch geladenen, massiven und klassischen Weltlinien, welche über Dilatongravitation wechselwirken, in Verbindung gesetzt. Somit verbessern wir eine, aus dem Kontext von Lösungen zu störungstheoretischen Bewegungsgleichungen, sowohl für das Gluon als auch für das Graviton, derselben Systeme, bekannte Zweifachkopievorschrift, formuliert von W. Goldberger und A. Ridgway. / We analyze several cases of mysterious connections between gauge and gravity theories, known as double copy relations. We focus on tree level scattering amplitudes in Einstein-(scalar-)-chromo-dynamics, i.e. scattering scenarios between gluons, massive fundamental quarks (scalars) and gravitons. In these scenarios we study the sub leading contribution to the adjacent collinear gluon limits in pure Yang-Mills amplitudes. Recently, S. Stieberger and T. Taylor have proposed a linear combination of amplitudes with a pair of collinear gluons to an Einstein-Yang-Mills amplitude. We present a proof of such relations using a novel representation of bosonic tree level amplitudes based on a localized integral on the Riemann sphere, called the Cachazo-He-Yuan formalism. Moreover, we give insight into an intriguing interplay between those relations and surprising gauge invariance violations of the sub-leading collinear gluon limit of Yang-Mills amplitudes. Next, we will focus on yet another set of relations between Yang-Mills amplitudes and Einstein-Yang-Mills amplitudes that were also proposed by S. Stieberger and T. Taylor. They directly relate single gluons to single gravitons. We show universality of such relations, i.e. their validity in the presence of massive fundamental quarks and scalars. For that purpose, we will use a Feynman diagrammatic approach which results in a novel color-to-kinematics rule, mapping gluons to gravitons in these scattering scenarios. Finally, we establish a novel double copy connection between classical effective actions of two massive classical worldlines which are colored and interacting in Yang-Mills theory and dilaton charged and interacting through dilaton-gravity. Doing so, we extend and improve existing work relating the same system of worldlines through a double copy at the level of perturbative solutions to the involved equations of motion for the gluon and graviton fields, as has been proposed by W. Goldberger and A. Ridgway.

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