A new visual registration algorithm (Adaptive Iterative Closest Keypoint, AICK) is tested and evaluated as a positioning tool on a Micro Aerial Vehicle (MAV). Captured frames from a Kinect like RGB-D camera are analyzed and an estimated position of the MAV is extracted. The hope is to find a positioning solution for GPS-denied environments. This thesis is focused on an indoor office environment. The MAV is flown manually, capturing in-flight RGB-D images which are registered with the AICK algorithm. The result is analyzed to come to a conclusion if AICK is viable or not for autonomous flight based on on-board positioning estimates. The result shows potential for a working autonomous MAV in GPS-denied environments, however there are some surroundings that have proven difficult. The lack of visual features on e.g., a white wall causes problems and uncertainties in the positioning, which is even more troublesome when the distance to the surroundings exceed the RGB-D cameras depth range. With further work on these weaknesses we believe that a robust autonomous MAV using AICK for positioning is plausible. / En ny visuell registreringsalgoritm (Adaptive Iterative Closest Keypoint, AICK) testas och utvärderas som ett positioneringsverktyg på en Micro Aerial Vehicle (MAV). Tagna bilder från en Kinect liknande RGB-D kamera analyseras och en approximerad position av MAVen beräknas. Förhoppningen är att hitta en positioneringslösning för miljöer utan GPS förbindelse, där detta arbete fokuserar på kontorsmiljöer inomhus. MAVen flygs manuellt samtidigt som RGB-D bilder tas, dessa registreras sedan med hjälp av AICK. Resultatet analyseras för att kunna dra en slutsats om AICK är en rimlig metod eller inte för att åstadkomma autonom flygning med hjälp av den uppskattade positionen. Resultatet visar potentialen för en fungerande autonom MAV i miljöer utan GPS förbindelse, men det finns testade miljöer där AICK i dagsläget fungerar undermåligt. Bristen på visuella särdrag på t.ex. en vit vägg inför problem och osäkerheter i positioneringen, ännu mer besvärande är det när avståndet till omgivningen överskrider RGB-D kamerornas räckvidd. Med fortsatt arbete med dessa svagheter är en robust autonom MAV som använder AICK för positioneringen rimlig.

<p>Insects and hummingbirds not only can perform long-term stationary hovering but also are capable of acrobatic maneuvers. At their body scale, such extraordinary flight performance remains unmatched by state-of-the-art conventional man-made aerial vehicles with fixed or rotary wings. Insects' and hummingbirds' near maximal performance come from their highly intricate and powerful wing-thorax actuation systems, sophisticated sensory system, and precise neuromotor control. Flapping Wing Micro Air Vehicles (FWMAVs) with bio-inspired flapping flight mechanisms hold great promise in matching the performance gap of their natural counterparts. Developing such autonomous flapping-wing vehicles to achieve animal-like flight, however, is challenging. The difficulties are mainly from the high power density requirements under the stringent constraints of scale, weight, and power, severe system oscillations induced by high-frequency wing motion, high nonlinearity of the system, and lack of miniature navigation sensors, which impede actuation system design, onboard sensing, flight control, and autonomous navigation. </p><p><br></p><p>To address these open issues, in this thesis, we first introduce systematic modeling of a dual-motor hummingbird-scale flapping wing robot. Based upon it, we then present studies of the onboard sensor fusion, flight control, and navigation method. </p><p><br></p><p>By taking the key inspiration from its natural counterparts, the proposed hummingbird robot has a pair of independently controlled wings. Each wing is directly actuated by a dc motor. Motors undergo reciprocating motion. Such a design is a severely underactuated system, namely, it relies on only two actuators (one per wing) to control full six degrees of freedom body motion. As a bio-inspired design, it also requires the vehicle close to its natural counterparts’ size and weight meanwhile provide sufficient lift and control effort for autonomy. Due to stringent payload limitation from severe underactuation and power efficiency challenges caused by motor reciprocating motion, the design and integration of such a system is a challenging task. In this thesis, we present the detailed modeling, optimization, and system integration of onboard power, actuation, sensing, and flight control to address these unique challenges. As a result, we successfully prototyped such dual-motor powered hummingbird robot, either with power tethers or fully untethered. The tethered platform is used for designing onboard sensing, control, and navigation algorithms. Untethered design tackles system optimization and integration challenges. Both tethered/untethered versions demonstrate sustained stable flight. </p><p><br></p><p>For onboard attitude sensing, a real-time sensor fusion algorithm is proposed with model-based adaptive compensation for both sensor reading drift and wing motion induced severe system vibration. With accurate and robust sensing results, a nonlinear robust control law is designed to stabilize the system during flight. Stable hovering and waypoint tracking flight were experimentally conducted to demonstrate the control performance. In order to achieve natural flyers' acrobatic maneuverability, we propose a hybrid control scheme by combining a model-based robust controller with a model-free reinforcement learning maneuver policy to perform aggressive maneuvers. The model-based control is responsible for stabilizing the robot in nominal flight scenarios. The reinforcement learning policy pushes the flight envelope to pilot fierce maneuvers. To demonstrate the effectiveness of the proposed control method, we experimentally show animal-like tight flip maneuver on the proposed hummingbird robot, which is actuated by only two DC motors. These successful results show the promise of such a hybrid control design on severely underactuated systems to achieve high-performance flight.</p><p><br></p><p>In order to navigate confined space while matching the design constraints of such a small robot, we propose to use its wings in dual functions - combining sensing and actuation in one element, which is inspired by animals' multifunctional flapping wings. Based on the interpretation of the motor current feedback which directly indicates wing load changes, the onboard somatosensory-like feedback has been achieved on our hummingbird robot. For navigation purposes, such a method can sense the presence of environmental changes, including grounds, walls, stairs, and obstacles, without the need for any other sensory cues. As long as the robot can fly, it can sense surroundings. To demonstrate this capability, three challenging tasks have been conducted onto the proposed hummingbird robot: terrain following, wall detection and bypass, and navigating a confined corridor. </p><p><br></p><p>Finally, we integrate the proposed methods into the untethered platform, which enables stable untethered flight of such a design in both indoor and outdoor tests. To the best of our knowledge, this result presents the first bio-inspired FWMAV powered by only two actuators and capable of performing sustained stable flight in both indoor and outdoor environment. It is also the first untethered flight of an at-scale tailless hummingbird robot with independently controlled wings, a key inspiration from its natural counterparts.</p><div><div><div><div><div> </div> </div> </div></div></div>

Micro Aerial Vehicles (MAVs) provide a highly capable, agile platform, ideally suited for intelligence/surveillance/reconnaissance missions, urban search and rescue, and scientific exploration. Critical to the success of these tasks is a system which moves au-tonomously through an unknown, obstacle-strewn, GPS-denied environment. Classical simultaneous localization and mapping (SLAM) approaches rely on large, heavy sensors to generate 3-D information about a MAV’s surroundings, severely limiting its abilities. This motivates a study of Parallel Tracking and Mapping (PTAM), an algorithm requiring only a single camera to provide 3-D data to an autonomous navigation system. Metric properties of 3-D MAV pose estimates are compared with physical measurements to ex-plore tracking accuracy. Additionally, a discrete wavelet transform-based keypoint detec-tor is implemented for a feasibility study on improving map density in low-visual-detail environments. Finally, a system is presented that integrates PTAM, autonomous MAV control, and a human interface for manual control and data logging.

Miniature air vehicles (MAVs) have attracted a large amount of interest recently both from the research community and from the public. New battery technologies as well as rapid developments in embedded processing and MEMS sensor technologies have greatly increased the potential of these vehicles. MAVs have been envisioned playing significant roles in both civil and military applications. Examples include: fire monitoring, search and rescue, traffic monitoring, crop monitoring, convoy protection, border surveillance, troop support, law enforcement, natural disaster relief, and aerial photography. The application of MAVs tends to center on the ability of the MAV to collect and deliver visual information to the user. In many applications it is important to be able to accurately geolocate items of interest in the visual data. However, the inaccuracies associated with MAV platforms have led to relatively large errors in previous attempts at geolocation. The first half of this thesis focuses on increasing the accuracy of geolocation estimates achievable using a hand-launchable MAV. To accomplish this, methods are presented for bias estimation, wind estimation, recursive least squares filtering, and optimal flight path generation. Hardware results are presented which demonstrate the ability to consistently localize targets to within 5 m regardless of wind conditions. The second half of this thesis focuses on using the high accuracy geolocation estimates to complete a search and engage mission. This is a mission in which the MAV not only locates the target, but also accurately delivers a payload to the target site. The focus is on delivering an attached payload via accurate landing at the target site. A vision-based landing approach is presented which is robust to both wind and moving targets. Simulation results are presented which demonstrate the effectiveness of the control.

No description available.

No description available.

The physics of flapping is very important in the design of MAVs. As MAVs cannot have an engine that produces the amount of thrust required for forward flight, and yet be light weight, harnessing thrust and lift from flapping is imperative for its design and development. In this thesis, aerodynamics of pitch and plunge are simulated using a 3-D, free wake, vortex lattice method (VLM), and structural characteristics of the wing are simulated as a membrane supported by a rigid frame. The aerodynamics is validated by comparing the results from the VLM model for constant angle of attack flight, pitching flight and plunging flight with analytical results, existing 2-D VLM and a doublet lattice method. The aeroelasticity is studied by varying parameters affecting the flow as well as parameters affecting the structure. The parametric studies are performed for cases of constant angle of attack, plunge and, pitch and plunge. The response of the aeroelastic model to the changes in the parameters are analyzed and documented. The results show that the aerodynamic loads increase for increased deformation, and vice-versa. For a wing with rigid boundaries supporting a membranous structure with a step change in angle of attack, the membrane oscillates about the steady state deformation and influence the loads. For prescribed oscillations in pitch and plunge, the membrane deformations and loads transition into a periodic steady state. / Master of Science

Energetic limitations in low scale Unmanned Aerial Vehicles (UAVs) sometimes turns outdoor field applications impractical, which restricts the realization of several tasks that could potentially be improved or benefited from its sounding characteristics. Depending on the mission, Mini Aerial Vehicles (MAVs) energetic resources may be mostly wasted during the round trip from launching base and target point around which a given mission must be accomplished. In this sense, the initial deployment problem becomes prominent, raising new opportunities on how aerial robots may be launched/deployed. This work presents a novel perspective in morphological adaptations for aerial robotics that may potentially minimize initial deployment problem issues. From that perspective, we present three novel morphologies. First refers to a hybrid fixed-wing/quadrotor aiming in-flight launching possibilities. Still looking at in-flight launching, second MAV regards to a new morphology for a quadrotor whose center of gravity is shifted in order to improve passive static stability. Third one relates to a hybrid MAV that combines a watercraft and a quadrotor. The aircraft may navigate on water with low energetic cost through a specially designed structure. It also presents static stability in air and over the ground. We present all details concerning new concepts, development, analysis, design and flight simulation for all three novel platforms. A concise and robust validation of stability control is firstly performed with the &#169;VICON vision system. Finally, on-the-field evaluation for all three morphologies are extensively carried out, presenting optimistic experimental results of our findings. / As limitações energéticas em robótica aérea de campo muitas vezes levam à sua não utilização em tarefas que poderiam se beneficiar substancialmente de suas inúmeras vantagens. Dependendo da complexidade da missão, os recursos energéticos podem ser despendidos prematuramente ainda durante o traslado ao ponto de interesse. Nesse contexto, se evidencia o problema do lançamento inicial de robôs, o que faz surgir novas possibilidades para o desenvolvimento de novas maneiras de lançá-los. Este trabalho propõe uma nova perspectiva para adaptações morfológicas para robótica aérea as quais podem significativamente minimizar os efeitos das limitações energéticas. Sob essa ótica, são propostas três novas morfologias. A primeira consiste de um robô aéreo híbrido asa fixa/quadrotor visando a possibilidade do lançamento em voo. A segunda consiste de uma aeronave de asa rotativa na configuração quadrotora morfologicamente adaptada para reposicionamento do seu centro de gravidade. O aumento da estabilidade estática passiva da aeronave também visa o seu lançamento durante o voo. A terceira se refere a um veículo aéreo híbrido que combina uma estrutura naval e um quadrotor, capaz de navegar em cenários aquáticos com baixo custo energético. O desenho mecânico resultante permite sua operação no ponto ótimo tanto para a navegação aérea quanto aquática, oferecendo estabilidade estática em todos os cenários (terra, ar e água). São apresentados todos os detalhes de conceito, concepção, análise, projeto e simulação em voo das três novas plataformas. Uma validação robusta dos sistemas de controle e estabilidade é realizada por sistema de visão ©VICON. Por fim, ensaios em campo são realizados, apresentando resultados experimentais otimistas para a aplicação das três novas morfologias.

Energetic limitations in low scale Unmanned Aerial Vehicles (UAVs) sometimes turns outdoor field applications impractical, which restricts the realization of several tasks that could potentially be improved or benefited from its sounding characteristics. Depending on the mission, Mini Aerial Vehicles (MAVs) energetic resources may be mostly wasted during the round trip from launching base and target point around which a given mission must be accomplished. In this sense, the initial deployment problem becomes prominent, raising new opportunities on how aerial robots may be launched/deployed. This work presents a novel perspective in morphological adaptations for aerial robotics that may potentially minimize initial deployment problem issues. From that perspective, we present three novel morphologies. First refers to a hybrid fixed-wing/quadrotor aiming in-flight launching possibilities. Still looking at in-flight launching, second MAV regards to a new morphology for a quadrotor whose center of gravity is shifted in order to improve passive static stability. Third one relates to a hybrid MAV that combines a watercraft and a quadrotor. The aircraft may navigate on water with low energetic cost through a specially designed structure. It also presents static stability in air and over the ground. We present all details concerning new concepts, development, analysis, design and flight simulation for all three novel platforms. A concise and robust validation of stability control is firstly performed with the &#169;VICON vision system. Finally, on-the-field evaluation for all three morphologies are extensively carried out, presenting optimistic experimental results of our findings. / As limitações energéticas em robótica aérea de campo muitas vezes levam à sua não utilização em tarefas que poderiam se beneficiar substancialmente de suas inúmeras vantagens. Dependendo da complexidade da missão, os recursos energéticos podem ser despendidos prematuramente ainda durante o traslado ao ponto de interesse. Nesse contexto, se evidencia o problema do lançamento inicial de robôs, o que faz surgir novas possibilidades para o desenvolvimento de novas maneiras de lançá-los. Este trabalho propõe uma nova perspectiva para adaptações morfológicas para robótica aérea as quais podem significativamente minimizar os efeitos das limitações energéticas. Sob essa ótica, são propostas três novas morfologias. A primeira consiste de um robô aéreo híbrido asa fixa/quadrotor visando a possibilidade do lançamento em voo. A segunda consiste de uma aeronave de asa rotativa na configuração quadrotora morfologicamente adaptada para reposicionamento do seu centro de gravidade. O aumento da estabilidade estática passiva da aeronave também visa o seu lançamento durante o voo. A terceira se refere a um veículo aéreo híbrido que combina uma estrutura naval e um quadrotor, capaz de navegar em cenários aquáticos com baixo custo energético. O desenho mecânico resultante permite sua operação no ponto ótimo tanto para a navegação aérea quanto aquática, oferecendo estabilidade estática em todos os cenários (terra, ar e água). São apresentados todos os detalhes de conceito, concepção, análise, projeto e simulação em voo das três novas plataformas. Uma validação robusta dos sistemas de controle e estabilidade é realizada por sistema de visão ©VICON. Por fim, ensaios em campo são realizados, apresentando resultados experimentais otimistas para a aplicação das três novas morfologias.

Många av dagens matematikläroböcker är multimodala som innebär att de innehåller fler kommunikationsformer som exempelvis skrift och bild. Denna studies bidrag var att konstruera verktyget MAV (Multimodalt Analysverktyg) som undersöker och identifierar multimodal text. Studien utgår från en sociosemiotisk teori och dess frågeställningar handlade om att undersöka hur skrift och bild förhåller sig till varandra, vad bilden har för funktion och hur den relaterar till skriften utifrån användning av MAV. Metoden som användes för att konstruera verktyget var att skapa kategorier utifrån begrepp från sociosemiotiken och applicera dem i två kodningsscheman. Kategorierna i det första kodningsschemat var: inramning, avstånd/närhet, överlappning och visuellt rim. Det andra kodningsschemat hade kategorierna: dekorativ, förankringsrelation och avbytesrelation. Resultatet visade att MAV kunde användas som verktyg i läroböckerna. Det visade också att skrift och bild ofta förhåller sig till varandra genom närhet och att de till mestadels skapar en förankringsrelation som innebär att de bidrar med ett likvärdigt matematiskt innehåll. En slutsats är att denna relation kan vara gynnsam för elevernas lärande eftersom innehållet kan vara abstrakt och att både skrift och bild behöver förmedla samma information. Det diskuterades även om vad den dekorativa bilden kan skapa för effekter i elevens lärande. / Many of today's mathematics textbooks are multimodal, which means that they contain more forms of communication such as writing and image. This study's contribution was to construct the MAV (Multimodal Analysis Tool) tool that investigates and identifies multimodal text. The study is based on a sociosemiotic theory and its issues were about investigating how the image and image relate to each other, what the image is for function and how it relates to the writing based on the use of MAV. The method used to construct the tool was to create categories based on concepts from socio-chemistry and apply them into two coding schemes. The categories in the first coding scheme were: framing, distance / proximity, overlap and visual rim. The second coding scheme had the categories: decorative, anchor relation, and interchange relation. The result showed that MAV could be used as a tool in the textbooks. It also showed that writing and image often relate to each other by close proximity and that they mostly create an anchoring relationship which means they contribute with an equivalent mathematical content. One conclusion is that this relationship can be beneficial to the students' learning because the content can be abstract and that both the writing and the image need to convey the same information. It was also discussed what the decorative image could create for effects in the student's learning.