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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
201

The effective use of multiple unmanned aerial vehicles in surface search and control

Berner, Robert Andrew 12 1900 (has links)
Approved for public release; distribution in unlimited. / This study analyzes the effective use of multiple unmanned aerial vehicles (UAVs) for the Navy's Surface Search and Control mission. In the future, the Navy hopes to leverage the capabilities of a family of UAVs to provide increased situational awareness in the maritime environment. This family of UAVs includes a Broad Area Maritime Surveillance (BAMS) UAV and Vertical Take-Off UAVs (VTUAVs). The concepts of operations for how these UAVs work together have yet to be determined. Questions exist about the best number of UAVs, types of UAVs, and tactics that will provide increased capabilities. Through modeling and agent-based simulation, this study explores the validity of future UAV requirements and provides insights into the effectiveness of different UAV combinations. For the scenarios modeled, the best UAV combination is BAMS plus two or three VTUAVs. However, analysis shows that small numbers of VTUAVs can perform as well without BAMS as they do with BAMS. For combinations with multiple UAVs, BAMS proves to be a valuable asset that not only reduces the number of missed classifications, but greatly improves the amount of coverage on all contacts in the maritime environment. BAMS tactics have less effect than the mere presence of BAMS itself. / Lieutenant, United States Navy
202

MINERAÇÃO DE DADOS DE IMAGENS OBTIDAS COM AERONAVE REMOTAMENTE PILOTADA PARA ESTIMATIVA DE PRODUTIVIDADE DO TRIGO

Gerke, Tiago 03 February 2017 (has links)
Made available in DSpace on 2017-07-21T14:19:29Z (GMT). No. of bitstreams: 1 TIAGO GERKE.pdf: 2494737 bytes, checksum: 62b5d2787dcdebe0e9ccf39bfa75f626 (MD5) Previous issue date: 2017-02-03 / Wheat cultivation plays an important role to Brazil and the world economic development, as well as in the human diet. The wheat Brazilian production is insufficient to meet the national demand, making research needed in order to improve the yield of this cereal. The goal of this work was to estimate wheat yield, searching for a predictive model through the data mining techniques, with data obtained from high spatial resolution images collected by unmanned aerial vehicles (UAV). The work was carried out in two experimental areas at Ponta Grossa city, Parana state, where for each area eight images were taken, at different culture development stages, with spatial resolution of 3.4cm/px and two images with resolution 10cm/px and 20cm/px, using an eBee UAV with an RGB and a NIR camera. The image processing was done with the Pix4D software, and resulted in an orthomosaics with reflectance values at different wavelengths: Red, Green and Blue, from the RGB camera and Red, Greed and NIR from the NIR camera, besides an image with NDVI values obtained from the arithmetic of NIR and Red wavelengths. The georeferencing correction of each orthomosaic and the extraction of the reflectance values were done with Quantum GIS geographic information system (GIS). From the extracted reflectance values, databases in different proportions (10%, 20%, 40%, 70% and 100%) were created for data mining, using the SMOReg algorithm, based on a support vector machine (SVM) for regression (SVR). The georreferencing correction using 10 control points provided ortomosaics with mean square error (RSME) of distance of 0.35m, which did not show significant difference compared to the correction with 5 control points (RMSE = 0.38m). The reflectance values were different for each study area, making it difficult to indicate better periods for estimating wheat yield. The highest correlation were obtained with data from RGB camera images, followed by the NIR and NDVI camera, with correlations of 0.6168,0.5423 and 0.5324, respectively. The amount of information extracted from the images, reflected in the proportion of the databases, was not significant to generated predictive models, as well as in the correlation indexes, which were statistically the same. Better correlation indices were obtained from the data extracted from the images with spatial resolution of 20cm/px, which suggests that high spatial resolution images may not be adequate for wheat yield estimation. / O cultivo do trigo desempenha um papel importante no desenvolvimento econômico de várias regiões do Brasil e do mundo, bem como na dieta humana. A produção brasileira do trigo é insuficiente para atender à demanda nacional, tornando necessárias pesquisas com intuito de melhorar a produtividade desse cereal. O objetivo desse trabalho foi a estimativa de produtividade do trigo, a partir da criação de modelos preditivos por meio da mineração de dados obtidos em imagens de alta resolução espacial, coletadas por aeronave remotamente pilotada (RPA). O trabalho foi realizado em duas áreas experimentais na cidade de Ponta Grossa – PR, onde para cada área foram feitas oito coletas de imagens, em diferentes estádios de desenvolvimento da cultura, com resolução espacial de 3,4cm/px e duas coletas com resolução 10cm/px e 20cm/px, através de uma RPA eBee utilizando uma câmera RGB e outra NIR. O processamento das imagens foi feito a partir do software Pix4D, e resultou em um ortomosaicos com os valores de refletância em diferentes comprimentos de onda: R, G e B da câmera RGB e R, G e NIR da câmera NIR, além de uma imagem com valores de NDVI obtidos a partir da aritmética das bandas Nir e Red (vermelho). A correção de georreferenciamento de cada ortomosaico e a extração dos valores de refletância foram feitas com auxílio do sistema de informação geográfica (SIG) Quantum GIS. A partir dos valores de refletância extraídos, foram criadas bases de dados em diferentes proporções (10%, 20%, 40%, 70% e 100%) para mineração de dados por meio do algoritmo SMOReg, baseado em máquina de vetor de suporte (SVM) para regressão (SVR). A correção de georreferenciamento utilizando 10 pontos de controle proporcionou ortomosaicos com erro médio quadrático (RSME) de distância de 0,35m, o qual não mostrou diferença significativa para a correção com 5 pontos de controle (RMSE = 0,38m). Os valores de refletância foram diferentes para cada área de estudo, tornando difícil a indicação de melhores períodos para a estimativa de produtividade do trigo. Os maiores índices de correlação da produtividade com os comprimentos de onda, foram obtidos com os dados das imagens da câmera RGB, seguido da câmera NIR e NDVI, com as correlações de 0,6168, 0,5423 e 0,5324, respectivamente. A quantidade de informação extraída das imagens, refletida na proporção das bases de dados, não se mostrou significativa nos modelos preditivos gerados, bem como nos índices de correlação, os quais foram estatisticamente iguais. Índices de correlação melhores foram obtidos a partir dos dados extraídos das imagens com resolução espacial de 20cm/px, o que sugere que imagens de alta resolução espacial podem não ser adequadas para estimativa de produtividade do trigo.
203

Modelling and controlling a bio-inspired flapping-wing micro aerial vehicle

Smith, David Everett 17 January 2012 (has links)
The objective of this research is to verify the three degree of freedom capabilities of a bio-inspired quad flapping-wing micro aerial vehicle in simulation and in hardware. The simulation employs a nonlinear plant model and input-output feedback linearization controller to verify the three degree of freedom capabilities of the vehicle. The hardware is a carbon fiber test bench with four flapping wings and an embedded avionics system which is controlled via a PD linear controller. Verification of the three degree of freedom capabilities of the quad flapping-wing concept is achieved by analyzing the response of both the simulation and test bench to pitch, roll, and yaw attitude commands.
204

論美國武裝無人機的國際法問題 / On International law issues concerning U.S. armed UAVs

王正, Wang, Cheng Unknown Date (has links)
無人飛行載具或簡稱無人機是一種不實際搭載乘員的飛行裝置,不論研發的目的為何其核心概念皆是希望以機械來代替人力從事較為辛苦或較為危險的工作;歷史上記載無人機由來已久,但是類議題真正受到國際社會關切乃是2001年9月11日九一一事件後才開始。為了回應九一一事件對美國的威脅,美國除了以行使自衛權為由進攻阿富汗外,更發動了以全球伊斯蘭極端主義份子為對象的「全球反恐戰爭」並且開始大量投入武裝無人機執行定點攻擊行動,狙殺蓋達組織領導人或是與其有關聯的極端主義團體的成員。 隨著反恐戰爭的推進,美國派出的武裝無人機架次也逐年上升,隨之而來的是急遽上升的傷亡人數;驟增的傷亡數,尤其是平民傷亡引起了國際社會關切,其中「美國的武裝無人機攻擊是否違反國際法上關於武力使用的規範」成了急待解決的問題。本論文以當前國際法上關於武力使用的兩大規範:使用武力的合法性(Jus ad bellum)、武力使用的方式(Jus in bello)為途徑,檢視當前美國武裝無人機攻擊是否符合前述兩大規範,進而替美國武裝無人機攻擊衍生的國際法問題提供一個解答。
205

Analysis and Design of a Multifunctional Spiral Antenna

Chen, Teng-Kai 2012 August 1900 (has links)
The Archimedean spiral antenna is well-known for its broadband characteristics with circular polarization and has been investigated for several decades. Since their development in the late 1950's, establishing an analytical expression for the characteristics of spiral antenna has remained somewhat elusive. This has been studied qualitatively and evaluated using numerical and experimental techniques with some success, but many of these methods are not convenient in the design process since they do not impart any physical insight into the effect each design parameter has on the overall operation of the spiral antenna. This work examines the operation of spiral antennas and obtains a closed-form analytical solution by conformal mapping and transmission line model with high precision in a wide frequency band. Based on the analysis of spiral antenna, we propose two novel design processes for the stripline-fed Archimedean spiral antenna. This includes a stripline feed network integrated into one of the spiral arms and a broadband tapered impedance transformer that is conformal to the spiral topology for impedance matching the nominally-high input impedance of the spiral. A Dyson-style balun located at the center facilitates the transition between guided stripline and radiating spiral modes. Measured and simulated results for a probe-fed design operating from 2 GHz to over 20 GHz are in excellent agreements to illustrate the synthesis and performance of a demonstration antenna. The research in this work also provides the possibility to achieve conformal integration and planar structural multi-functionality for an Unmanned Air Vehicle (UAV) with band coverage across HF, UHF, and VHF. The proposed conformal mapping analysis can also be applied on periodic coplanar waveguides for integrated circuit applications.
206

Magnetic signature characterization of a fixed-wing vertical take-off and landing (VTOL) unmanned aerial vehicle (UAV)

Hansen, Cody Robert Daniel 17 December 2018 (has links)
The use of magnetometers combined with unmanned aerial vehicles (UAVs) is an emerging market for commercial and military applications. This study presents the methodology used to magnetically characterize a novel fixed-wing vertical take-off and landing (VTOL) UAV. The most challenging aspect of integrating magnetometers on manned or unmanned aircraft is minimizing the amount of magnetic noise generated by the aircraft’s onboard components. As magnetometer technology has improved in recent years magnetometer payloads have decreased in size. As a result, there has been an increase in opportunities to employ small to medium UAV with magnetometer applications. However, in comparison to manned aviation, small UAVs have smaller distance scales between sources of interference and sensors. Therefore, more robust magnetic characterization techniques are required specifically for UAVs. This characterization determined the most suitable position for the magnetometer payload by evaluating the aircraft’s static-field magnetic signature. For each aircraft component, the permanent and induced magnetic dipole moment characteristics were determined experimentally. These dipole characteristics were used to build three dimensional magnetic models of the aircraft. By assembling the dipoles in 3D space, analytical and numerical static-field solutions were obtained using MATLAB computational and COMSOL finite element analysis frameworks. Finally, Tolles and Lawson aeromagnetic compensation coefficients were computed and compared to evaluate the maneuver noise for various payload locations. The magnetic models were used to study the sensitivity of the aircraft configuration and to simultaneously predict the effects at potential sensor locations. The study concluded by predicting that a wingtip location was the area of lowest magnetic interference. / Graduate
207

Modelagem matemática e controle de atitude e posição do quadrotor / Mathematical modeling and attitude control and position quadrotor

Benigno, Tayara Crystina Pereira 28 August 2015 (has links)
Made available in DSpace on 2016-08-31T13:33:46Z (GMT). No. of bitstreams: 1 TayaraCPB_Dissert.pdf: 1984521 bytes, checksum: 5a46c1781124a49b404a083b87b969bd (MD5) Previous issue date: 2015-08-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / With advances in technology and the popularization of the use of Unmanned Aerial Vehicles (UAV's) so does the need to use more robust and more effective control techniques. Among the various types of unmanned aerial vehicles, this paper will focus on quadrotor model, which has a mechanical structure in the form of x, whose ends have an engine and propeller assembly, where the rotation of this group is responsible for the lift and the movements developed by quadrotor. This feeling, aiming to apply drivers that provide stability to the dynamic system. This study aims to conduct mathematical modeling using the Euler-Lagrange. With this, it is proposed a PID controller (Proportional Integral Derivative) to maintain stable the three orientation angles and height to a desired value. The development of the proposed controller will be validated via simulation confirming the application feasibility of the technique presented stability / Com o avanço tecnológico e a popularização do uso dos Veículos Aéreos Não Tripulados (VANT s) cresce também a necessidade do uso de técnicas de controle mais robustas e mais eficazes. Dentre os mais diversos tipos de veículos aéreos não tripulados, este trabalho irá focar no modelo do quadrotor, que possui uma estrutura mecânica em forma de cruz, cujas extremidades têm um conjunto de motor e hélice, onde a rotação desse conjunto é responsável pela força de sustentação e pelos movimentos desenvolvidos pelo mesmo. Objetivando aplicar controladores que proporcione estabilidade ao sistema dinâmico deste veiculo aéreo. O presente trabalho tem como objetivo realizar a modelagem matemática deste sistema usando as equações de Euler-Lagrange. Tendo isso, é proposto um controlador PID (Proporcional Integral Derivativo) para manter os três ângulos de orientação estáveis e a altura em um valor desejado. O desenvolvimento do controlador proposto será validado via simulação confirmando a viabilidade da aplicação da técnica de estabilidade apresentada
208

Sincronização por pós-processamento de um Sistema de Varredura a LASER embarcado em VANT / Post-processing synchronization of a LASER Scanning System onboard UAV

Machado, Marcela do Valle [UNESP] 23 February 2018 (has links)
Submitted by MARCELA DO VALLE MACHADO (marcelavmachado@gmail.com) on 2018-04-22T02:22:02Z No. of bitstreams: 1 machado_mv_me_prud.pdf: 3915564 bytes, checksum: a8e42c5376b44043a216b005b6c1615a (MD5) / Approved for entry into archive by Claudia Adriana Spindola null (claudia@fct.unesp.br) on 2018-04-23T11:50:28Z (GMT) No. of bitstreams: 1 machado_mv_me_prud.pdf: 3915564 bytes, checksum: a8e42c5376b44043a216b005b6c1615a (MD5) / Made available in DSpace on 2018-04-23T11:50:28Z (GMT). No. of bitstreams: 1 machado_mv_me_prud.pdf: 3915564 bytes, checksum: a8e42c5376b44043a216b005b6c1615a (MD5) Previous issue date: 2018-02-23 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Devido ao elevado custo de Sistemas de Varredura a LASER Aerotransportados (SVLA) e a miniaturização de sensores, sistemas de varredura a LASER (SVL) de menor peso e custo têm sido uma alternativa para estudos florestais. Aliado a estes sistemas, a crescente utilização de Veículos Aéreos Não Tripulados (VANT) possibilita a aquisição de dados com maior flexibilidade e rapidez, o que permite a utilização de SVL mais leves neste tipo de plataforma. Todavia, a integração e sincronização dos dispositivos do sistema demanda árduo trabalho de conexão eletrônica e computacional. Em casos que não seja possível realizar a sincronização eletrônica entre os dispositivos do sistema, uma alternativa é a sincronização por pósprocessamento, estabelecida por meio da relação entre os dados temporais obtidos com o LIDAR (Light Detection and Ranging) e com o GNSS (Global Navigation Sattelite Systems), durante a trajetória de voo do SVL embarcado em VANT. Para relacionar estes dados, são realizadas manobras de voo na forma senoidal durante a decolagem e pouso com o sistema, a fim de gerar pontos de máximos e mínimos. Com isso, os dados LASER e as posições da plataforma, coletados pelos dispositivos LASER e GNSS/IMU em sistemas de tempo diferentes, são relacionados por meio da diferença de distância e altura em função do tempo. Posteriormente, o tempo dos dados LASER é corrigido para tempo GPS, caracterizando a sincronização por pós-processamento, e refinado pelo Método dos Mínimos Quadrado. Desse modo, a nuvem de pontos pode então ser gerada. O controle de qualidade altimétrico utilizando pontos de apoio coletados em campo, apresentou uma acurácia de 11,6 cm. Para o controle planimétrico foi verificada uma acurácia de 45 cm para a componente E e 62 cm para a componente N. A partir das acurácias encontradas para a nuvem de pontos, conclui-se que a técnica de sincronização empregada é uma alternativa viável para relacionar dispositivos desacoplados de um SVL e que a acurácia centimétrica do sistema permite que este seja empregado em diversas aplicações, dentre as quais estão estimativa de altura de árvores. / Due to the high cost of Airborne LASER Scanning (ALS) and the miniaturization of sensors, low-cost and low-weight LASER systems have been an alternative for forestry studies. Together with these systems, the increasing use of Unmanned Aerial Vehicles (UAV) platforms, also low cost, enables the acquisition of data with greater flexibility and speed, which allows the use of low-weight SVL in this type of platform. However, the integration and synchronization of the devices of the system demands specialised work for electronic and computational connections. In cases where it is not possible to perform electronic synchronization between the devices of the system, an alternative is the post-processing synchronization, established through the relationship between the signals obtained with LIDAR (Light Detection and Ranging) and GNSS (Global Navigation Sattelite Systems), during the flight path of the SVL boarded in UAV. To relate these signals, flight maneuvers are performed in the a sinusoidal form shape during takeoff and landing with the system in order to obtain peaks of maximum and minimum. Thus, the LASER data and platform positions collected by the LASER and GNSS / IMU devices in different time systems are related by distance and height as a function of time. Subsequently, the LASER data time is corrected to match GPS time, characterizing the post-processing synchronization, and latter refined by the Least Square Method. In this way, the point cloud can then be generated. The quality control for altimetry, using control points collected in the field, achieved an obtained accuracy of 11.6 cm. The planimetric quality control achieve an accuracy of 45 cm the E component and 62 cm for the N component. From the accuracy achieved for the point cloud, it was concluded that the synchronization technique used is a viable alternative to relate decoupled devices of an ALS and that the centimetric accuracy of the system allows it to be used in several applications, such as tree height estimation. / FAPESP Proc. nº 2013/50426-4
209

Modelagem dinâmica e controle para navegação de um veículo aéreo não tripulado do tipo quadricóptero

Lima, Gabriela Vieira 14 August 2015 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Technological advances in electromechanical sensor and actuators, energy storage, data processing and control methodology made possible the development of unmanned aerial vehicles (UAVs). The quadrotor has emerged as one of these research platforms due to its mechanical simplicity, high maneuverability, as well as its capability of hovering and perform vertical take-off and landing. However, such vehicle presents some challenging issues to control area, like: nonlinearity, time-varying behavior, in addition it belongs to the class of underactuated mechanical systems, and it is subject to aerodynamics disturbances and parametric uncertainties. Therefore, this dissertation has as main objective, contribute to development and control strategies implementation to solve the positioning and path tracking problems of unmanned aerial vehicles, focusing on an underactuated mechanical system. In order to obtain a dynamic model that represents the aerial vehicle properly and realistically, the motion equations were developed based on the physics laws that define the mechanical system. The model we obtained is decoupled, thus we consider the presence of two subsystems, the rotational and the translational ones. A cascade control strategy was implemented, so that, a model predictive control (MPC) was developed to the altitude and orientation control of the aerial vehicle. However, the positioning control along the xy axis was performed through a proportional integral derivative control (PID). Such strategies allowed a smooth path tracking, beyond the possibility of dealing with physical constraints of the system. In order to assess the robustness of the control structure shown, we performed flight simulations under the presence of aerodynamics disturbances and parametric uncertainties. / Avanços tecnológicos em sensores e atuadores microeletromecânicos, no armazenamento de energia, no processamento de informações e em metodologias de controle possibilitaram o desenvolvimento dos veículos aéreos não tripulados (VANT s). O quadricóptero tem emergido como uma destas plataformas de pesquisa devido a sua simplicidade mecânica, a alta manobrabilidade, bem como a capacidade de realizar pairagem e decolagens e pousos verticais. Contudo, tal veículo apresenta algumas características desafiadoras para a área de controle, como: não linearidades, comportamento variante no tempo, além de pertencer à classe dos sistemas mecânicos subatuados e estar sujeito a distúrbios aerodinâmicos e incertezas paramétricas. Desta forma, este trabalho possui como principal objetivo contribuir para o desenvolvimento e a implementação de estratégias de controle para solucionar os problemas de posicionamento e rastreamento de trajetória em veículos aéreos não tripulados, focando em um sistema mecânico subatuado. Com o intuito de obter um modelo dinâmico que represente de forma apropriada e realista o veículo aéreo, suas equações de movimento foram desenvolvidas baseando-se nas leis físicas que regem o sistema mecânico. O modelo obtido é desacoplado, portanto, consideramos a existência de dois subsistemas, o rotacional e o translacional. Uma estratégia de controle em cascata foi implementada, de modo que, um controle preditivo baseado em modelo (CPBM) foi desenvolvido para o controle da altitude e da orientação do veículo aéreo. Já o controle de posicionamento no eixo xy foi efetuado através de um controlador proporcional integral derivativo (PID). Tais estratégias permitiram um rastreamento de trajetória suave, além da possibilidade de lidar com as restrições físicas do sistema. Com o intuito de avaliar a robustez da estrutura de controle apresentada, foram realizadas simulações de voo na presença de distúrbios aerodinâmicos e incertezas paramétricas. / Mestre em Ciências
210

Controle não linear para um veículo aéreo não tripulado : aspectos teóricos e numéricos

Silva, Carlos Augusto Nogueira da January 2018 (has links)
Orientador: Prof. Dr. André Fenili / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Engenharia Mecânica, Santo André, 2018.

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