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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.
1

Aerodynamic interactions of non-planar rotors

Bennetts, Alexander January 2018 (has links)
The aim of this thesis is to improve understanding of the effects of rotor-rotor interference on small scale rotor systems used on Micro Air Vehicles (MAVs). Previous research on rotor-rotor interactions has focused primarily on planar co-axial and tandem rotors of large scale rotorcraft. The work presented is distinct from prior research not only in its consideration of non-planar rotor systems, but also because of the lower Reynolds numbers and the use of fixed-pitch variable-speed propulsion systems. A design for a novel adjustable rotor interaction test-rig is presented along with a methodology for acquiring accurate and repeatable steady state performance data for two interacting rotor systems. Two six-axis force balances are used to acquire instantaneous and time averaged force and torque data and PIV is used to derive instantaneous and time-averaged flow field data for single and interacting rotor cases. The resulting performance and flow field data represents a unique dataset that can be used in the analysis of small scale rotor interactions, and in the validation of CFD investigations. Results show that for disc angles of between 180 degrees and 90 degrees interactions between rotors are negligible. As the disc angle is reduced from the orthogonal case to the coaxial case interactions significantly effect thrust, pitching moment, and efficiency. It is recommended that in the design of non-planar multirotor vehicles disc angles greater than 75 degrees are utilised to avoid the strong rotor-rotor interactions seen at lower disc angles. A review of existing and future non-planar multirotor concepts shows that the majority avoid significant rotor interactions by virtue of large disc angles.
2

Simulace kooperativního dohledu pomocí bezpilotních letounů za použití platforem Pogamut a USARsim / Simulation of Multi-UAV Cooperative Surveillance Using Pogamut and USARSim

Dufek, Jan January 2014 (has links)
The main objective of this thesis is to introduce a simulation platform, which has been developed utilizing Pogamut and USARSim, for cooperative aerial surveillance using multiple unmanned aerial vehicles (UAVs). The graphical user interface (GUI) of the simulator contains the automatically created bird's eye view of a 3D virtual environment. This is used to enter locations and parameters of objects (UAVs, charging stations and areas) and also to visualize the process of a simulation. The thesis proposes a system for the analysis of the quality of surveillance, whose results are presented in the GUI in the form of a time graph and a heat map. Part of the proposed platform is a UAV objective-based control system including charging stations scheduling. A total of seven algorithms for cooperative surveillance has been implemented, tested in three different scenarios and analyzed for coverage quality. Powered by TCPDF (www.tcpdf.org)
3

An evaluation of the potential to use drone deliveries as last-mile logistics : In Jämtland

Desloovere, Wout January 2020 (has links)
The purpose of this thesis is to investigate the potential of delivery drones to contribute to the logistic network (specifically the last-mile), while reducing the environmental impact, in the region of Jämtland, Sweden. This is done by making a current technological overview of delivery drones. Using this summary, it is possible to estimate the possibilities of the technology itself. Best practises are gathered and analysed since it is valuable to learn from the previous experiences. The environmental impact of drone delivery is analysed because the main reason to use drones in Jämtland, should be to reduce the overall environmental impact of the logistic sector. This is combined with the legislation and challenges drones face. Hereby it is possible to determine when drone delivery could reduce the environmental impact of last-mile logistics. Drones or Unmanned Aerial Vehicles (UAV’s) are claimed by many companies (Google, Amazon, UPS) in the logistic sector to be a great technology for last-mile delivery, which is faced with high costs. Delivery drones promise to be cost reducing, fast and eco-friendly. There is a vast amount of research going into planning and economics of delivery drones for the logistic sector. The research on the environmental impact is limited and outcomes are highly dependent on the limitations of the study. Therefore, it is hard to analyse in which situations delivery drones can contribute to the society by lowering the environmental impact of the logistic sector, while following current trends of faster deliveries. The main findings are: the ideal case is a single light package or payload that needs to be transported, without the possibility for other packages to be delivered on the same route. Once package deliveries can be grouped in an efficient route, there are better technologies on the market nowadays. These are further developed and have a lower impact on the environment. Even if drones can be used in a way that benefits the environment and is cost-efficient, they still face challenges. More testing and scientific research is needed to prove drone delivery can be done in a safe manner, that benefits the environment while being cost-effective. / <p>2020-06-10</p>
4

Monitoramento de remanescentes florestais urbanos com ve?culo a?reo n?o tripulado / Monitoring urban forest remnants with an unmanned aerial vehicle

Alves, Jos? Ricardo 18 December 2017 (has links)
Submitted by SBI Biblioteca Digital (sbi.bibliotecadigital@puc-campinas.edu.br) on 2018-06-13T12:23:13Z No. of bitstreams: 1 JOSE RICARDO ALVES.pdf: 4604947 bytes, checksum: f43a40d3029436f7ad7bf03fe51c7e87 (MD5) / Made available in DSpace on 2018-06-13T12:23:14Z (GMT). No. of bitstreams: 1 JOSE RICARDO ALVES.pdf: 4604947 bytes, checksum: f43a40d3029436f7ad7bf03fe51c7e87 (MD5) Previous issue date: 2017-12-18 / Pontif?cia Universidade Cat?lica de Campinas - PUC - Campinas / The aim of this dissertation was to use current technology to collect environmental quantities of forests to perform a periodic monitoring that would aid in preventing the advance of degradation and deforestation of the urban forest remnants of Campinas, more specifically Mata do Quilombo, located in the Bar?o Geraldo district. The use of Unmanned Aerial Vehicles (UAV) in the diagnosis and preservation of this urban forest remnant provided a low-cost method and a non-invasive monitoring. The strategy was to use the UAV with embedded remotely-activated electronic sensors in order to collect units of environmental quantities such as the location of clearings within the forest created by deforestation, air temperature and humidity, luminosity and the georeferenced location of the study site. In addition to the UAV technology, wireless technology was also used to communicate with various frequency bands, thus validating the simultaneous operation of the embedded sensors without any interference between them or external sources. After the data was collected, the objective was to submit it to an outlier verification method and make them available in a monitoring center, so that the user could later save this information in a remote access system known as supervisory system. / Esse trabalho teve o intuito de utilizar tecnologias atuais para coleta das grandezas ambientais das matas para realizar um acompanhamento peri?dico dos remanescentes florestais urbanos de Campinas, mais especificamente a Mata do Quilombo, localizada no distrito de Bar?o Geraldo, que auxiliasse na preven??o do avan?o da degrada??o frequente e do desmatamento. A utiliza??o do VANT (Ve?culo A?reo N?o Tripulado) no diagn?stico e preserva??o desse remanescente florestal urbano proporcionou um m?todo de baixo custo e uma avalia??o de forma n?o invasiva. A estrat?gia visou utilizar o VANT com sensores eletr?nicos embarcados acionados remotamente afim de capturar unidades de grandezas ambientais como a localiza??o de clareiras no interior da mata provindas do desmatamento, temperatura e umidade do ar, luminosidade e localiza??o georreferenciada do local de estudo. Aliada ? tecnologia do VANT, tamb?m foi utilizada a tecnologia de comunica??o sem fio com diversas faixas de frequ?ncias, validando assim o funcionamento desses sensores embarcados em atividade simult?nea sem que houvesse interfer?ncias entre os mesmos e de meios externos. Ap?s a coleta, o intuito foi submeter os dados coletados a um tratamento de verifica??o de outlier (m?todo de descarte de dados que se distanciam dos demais) e disponibiliz?-los numa central de monitoramento, de forma que o usu?rio pudesse salvar essas informa??es posteriormente num servidor de acesso remoto conhecido como sistema supervis?rio.
5

Estimation of Drone Location Using Received Signal Strength Indicator

Jagini, Varun Kumar 08 1900 (has links)
The main objective of this thesis is to propose a UAV (also called as drones) location estimation system based on LoRaWAN using received signal strength indicator in a GPS denied environment. The drones are finding new applications in areas such as surveillance, search, rescue missions, package delivery, and precision agriculture. Nearly all applications require the localization of UAV during flight. Localization is the method of determining a UAVs physical position using a real or virtual coordinate system. This thesis proposes a LoRaWAN-based UAV location method and presents experimental findings from a prototype. The thesis mainly consists of two different sections: one is the distance estimation and the other is the location estimation. First, the distance is estimated based on the mean RSSI values which are recorded at the ground stations using the path loss model. Later using the slant distance estimation technique, the path loss model parameters L and C are estimated whose values are unknown at the beginning. These values completely depend on the environment. Finally, the trilateration system architecture is employed to find the 3-D location of the UAV.
6

Entwicklung und Modellierung einer vollaktuierten Drohne

Schuster, Micha 26 April 2018 (has links)
Diese Diplomarbeit beschäftigt sich mit der geometrischen Auslegung und Regelung einer vollaktuierten Drohne, die als fliegende Arbeitsplattform für einen Manipulator dienen soll. Dabei werden ausgehend von der geometrischen Beschreibung einer allgemeinen, symmetrischen Drohne mit sechs Rotoren Methoden entwickelt, die den anforderungsbezogenen Entwurf der Geometrie einer vollaktuierten Drohne ermöglichen. Darüber hinaus werden prinzipielle Einflussmechanismen einzelner Geometrieparameter auf die durch die Drohne erzeugbaren Kräfte und Momente aufgezeigt. Zur Charakterisierung des Raums aller erzeugbaren Lasten wird dieser auf sogenannte Stützvektoren reduziert. Als Stützvektoren dienen dabei die für den Schwebeflug nötige Schubkraft, die garantierte Mindestkraft in horizontaler Richtung und das garantierte Mindestmoment um eine beliebige Achse, zu deren Berechnung zusätzlich analytische Formeln hergeleitet werden. Aufbauend auf die Beschreibung durch Stützvektoren wird die Formuliernung von Metriken vorgestellt, die die Bewertung einer Drohnengeometrie durch eine einzige skalare Maßzahl ermöglichen, wodurch die je nach Anwendung optimale Drohnengeometrie ermittelt werden kann. Zur Regelung des Systems aus Drohne und Manipulator wurde ein Regelungskonzept entwickelt, welches durch eine Entkopplung der Bewegungsgleichungen eine virtuelle Verschiebung des Schwerpunkts in das Drohnenzentrum realisiert und so eine präzise Regelung unabhängig von der tatsächlichen Schwerpunktlage ermöglicht. / This thesis’ subject is the geometrical design and control of a fully actuated drone, intended to be used as a flying operating-platform for a manipulator. Starting with the general geometrical description of a symmetric drone with six rotors, methods for the application specific design of a fully actuated drone are developed. Furthermore general influencing principles of geometric parameters on the forces and torques that can be generated by the drone, are pointed out. To characterize the drone's wrench-space, it is reduced to so called support vectors, which are given by the hovering thrust, the minimum guaranteed force in a horizontal direction and the minimum guaranteed torque in any direction. Additionally, analytic formulas are derived for the mentioned support vectors. Based on the description by the support vectors, a formulation of metrics is introduced, to enable the assessment of a specific drone geometry by a single scalar measure, to determine the ideal drone geometry for a specific application. Targeting the issue of controlling the flight system, consisting of the drone and the manipulator, a concept is developed that realizes a virtual dissplacement of the center of mass by decoupling the equations of motion and therby facilitates a precise control, independent of the actual location of the system's center of mass.

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